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  • 1.
    Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco.;LPTPM, Oujda, Morocco..
    Collaboration, A. T. L. A. S.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    et al.,
    Measurements of Higgs boson properties in the diphoton decay channel with 36 fb(-1) of pp collision data at root s=13 TeV with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 5, artikel-id 052005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Properties of the Higgs boson are measured in the two-photon final state using 36.1 fb(-1) of proton-proton collision data recorded at root s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. Cross-section measurements for the production of a Higgs boson through gluon-gluon fusion, vector-boson fusion, and in association with a vector boson or a top-quark pair are reported. The signal strength, defined as the ratio of the observed to the expected signal yield, is measured for each of these production processes as well as inclusively. The global signal strength measurement of 0.99 +/- 0.14 improves on the precision of the ATLAS measurement at root s = 7 and 8 TeV by a factor of two. Measurements of gluon-gluon fusion and vector-boson fusion productions yield signal strengths compatible with the Standard Model prediction. Measurements of simplified template cross sections, designed to quantify the different Higgs boson production processes in specific regions of phase space, are reported. The cross section for the production of the Higgs boson decaying to two isolated photons in a fiducial region closely matching the experimental selection of the photons is measured to be 55 +/- 10 fb, which is in good agreement with the Standard Model prediction of 64 +/- 2 fb. Furthermore, cross sections in fiducial regions enriched in Higgs boson production in vector-boson fusion or in association with large missing transverse momentum, leptons or top-quark pairs are reported. Differential and double-differential measurements are performed for several variables related to the diphoton kinematics as well as the kinematics and multiplicity of the jets produced in association with a Higgs boson. These differential cross sections are sensitive to higher order QCD corrections and properties of the Higgs boson, such as its spin and CP quantum numbers. No significant deviations from a wide array of Standard Model predictions are observed. Finally, the strength and tensor structure of the Higgs boson interactions are investigated using an effective Lagrangian, which introduces additional CP-even and CP-odd interactions. No significant new physics contributions are observed.

  • 2. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Measurements of t(t)over-bar differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pp collisions at root s=13 Te V using the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 1, artikel-id 012003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t (t) over bar system kinematic observables using proton-proton collisions at a center-of-mass energy of root s = 13 TeV. The data set corresponds to an integrated luminosity of 36.1 fb(-1), recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum p(T) > 500 GeV and a second with p(T) > 350 GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a b-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated chi(2) values. The cross-section for t (t) over bar production in the fiducial phase-space region is 292 +/- 7(stat) +/- 71(syst) tb, to be compared to the theoretical prediction of 384 +/- 36 fb.

  • 3. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for B - L R-parity-violating top squarks in root s=13 TeV pp collisions with the ATLAS experiment2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 3, artikel-id 032003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search is presented for the direct pair production of the stop, the supersymmetric partner of the top quark, that decays through an R-parity-violating coupling to a final state with two leptons and two jets, at least one of which is identified as a b-jet. The data set corresponds to an integrated luminosity of 36.1 fb(-1) of proton-proton collisions at a center-of-mass energy of root s = 13 TeV, collected in 2015 and 2016 by the ATLAS detector at the LHC. No significant excess is observed over the Standard Model background, and exclusion limits are set on stop pair production at a 95% confidence level. Lower limits on the stop mass are set between 600 GeV and 1.5 TeV for branching ratios above 10% for decays to an electron or muon and a b-quark.

  • 4. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for heavy resonances decaying to a photon and a hadronically decaying Z/W/H boson in pp collisions at root s=13 TeV with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 3, artikel-id 032015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many extensions of the Standard Model predict new resonances decaying to a Z, W, or Higgs boson and a photon. This paper presents a search for such resonances produced in pp collisions at root s = 13 TeV using a data set with an integrated luminosity of 36.1 fb(-1) collected by the ATLAS detector at the LHC. The Z/W/H bosons are identified through their decays to hadrons. The data are found to be consistent with the Standard Model expectation in the entire investigated mass range. Upper limits are set on the production cross section times branching fraction for resonance decays to Z.W + gamma in the mass range from 1.0 to 6.8 TeV and for the first time into H + gamma in the mass range from 1.0 to 3.0 TeV.

  • 5. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for Higgs bosons produced via vector-boson fusion and decaying into bottom quark pairs in root s=13 TeV pp collisions with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 5, artikel-id 052003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for the b (b) over bar decay of the Standard Model Higgs boson produced through vector-boson fusion is presented. Three mutually exclusive channels are considered: two all-hadronic channels and a photon-associated channel. Results are reported from the analysis of up to 30.6 fb(-1) of pp data at root s = 13 TeV collected with the ATLAS detector at the LHC. The measured signal strength relative to the Standard Model prediction from the combined analysis is 2.5(-1.3)(+1.4) for inclusive Higgs boson production and 3.0(-1.6)(+1.7) for vector-boson fusion production only.

  • 6. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for resonances in the mass distribution of jet pairs with one or two jets identified as b-jets in proton-proton collisions at root s=13 TeV with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 3, artikel-id 032016Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for new resonances decaying into jets containing b-hadrons in pp collisions with the ATLAS detector at the LHC is presented in the dijet mass range from 0.57 to 7 TeV. The data set corresponds to an integrated luminosity of up to 36.1 fb(-1) collected in 2015 and 2016 at root s = 13 TeV. No evidence of a significant excess of events above the smooth background shape is found. Upper cross-section limits and lower limits on the corresponding signal mass parameters for several types of signal hypotheses are provided at 95% C.L. In addition, 95% C.L. upper limits are set on the cross sections for new processes that would produce Gaussian-shaped signals in the di-b-jet mass distributions.

  • 7. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for top squarks decaying to tau sleptons in pp collisions at root s=13 TeV with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 3, artikel-id 032008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for direct pair production of top squarks in final states with two tau leptons, b-jets, and missing transverse momentum is presented. The analysis is based on proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 36.1 fb(-1) recorded with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. Two exclusive channels with either two hadronically decaying tau leptons or one hadronically and one leptonically decaying tau lepton are considered. No significant deviation from the Standard Model predictions is observed in the data. The analysis results are interpreted in terms of model-independent limits and used to derive exclusion limits on the masses of the top squark (t) over tilde (1) and the tau slepton (tau) over tilde (1) in a simplified model of supersymmetry with a nearly massless gravitino. In this model, masses up to m((t) over tilde (1)) = 1.16 TeV and m ((tau) over tilde (1)) = 1.00 TeV are excluded at 95% confidence level.

  • 8. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Measurements of integrated and differential cross sections for isolated photon pair production in pp collisions at root s=8 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 11, artikel-id 112005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A measurement of the production cross section for two isolated photons in proton-proton collisions at a center-of-mass energy of root s = 8 TeV is presented. The results are based on an integrated luminosity of 20.2 fb(-1) recorded by the ATLAS detector at the Large Hadron Collider. The measurement considers photons with pseudorapidities satisfying vertical bar eta(gamma)vertical bar< 1.37 or 1.56 <vertical bar eta(gamma)vertical bar< 2.37 and transverse energies of respectively E-T,1(gamma) > 40 GeV and E-T,2(gamma) > 30 GeV for the two leading photons ordered in transverse energy produced in the interaction. The background due to hadronic jets and electrons is subtracted using data-driven techniques. The fiducial cross sections are corrected for detector effects and measured differentially as a function of six kinematic observables. The measured cross section integrated within the fiducial volume is 16.8 +/- 0.8 pb. The data are compared to fixed-order QCD calculations at next-to-leading-order and next-to-next-to-leading-order accuracy as well as next-to-leading-order computations including resummation of initial-state gluon radiation at next-to-next-to-leading logarithm or matched to a parton shower, with relative uncertainties varying from 5% to 20%.

  • 9. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for dark matter in association with a Higgs boson decaying to two photons at root s=13 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 11, artikel-id 112004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector, corresponding to an integrated luminosity of 36.1 fb(-1) of proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015 and 2016. No significant excess over the expected background is observed. Upper limits at 95% confidence level are set on the visible cross section for beyond the Standard Model physics processes, and the production cross section times branching fraction of the Standard Model Higgs boson decaying into two photons in association with missing transverse momentum in three different benchmark models. Limits at 95% confidence level are also set on the observed signal in two-dimensional mass planes. Additionally, the results are interpreted in terms of 90% confidence-level limits on the dark-matternucleon scattering cross section, as a function of the dark-matter particle mass, for a spin-independent scenario.

  • 10. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for squarks and gluinos in events with an isolated lepton, jets, and missing transverse momentum at root s=13 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 11, artikel-id 112010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of a search for squarks and gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton-proton collision data at a center-of-mass energy of root s = 13 TeV are presented. The data set used was recorded during 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb(-1). No significant excess beyond the expected background is found. Exclusion limits at 95% confidence level are set in a number of supersymmetric scenarios, reaching masses up to 2.1 TeV for gluino pair production and up to 1.25 TeV for squark pair production.

  • 11.
    Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco.;LPTPM, Oujda, Morocco..
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    et al.,
    Search for squarks and gluinos in final states with jets and missing transverse momentum using 36 fb(-1) of root s=13 TeV pp collision data with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 11, artikel-id 112001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded in 2015 and 2016 by the ATLAS experiment in root s = 13 TeV proton-proton collisions at the Large Hadron Collider, corresponding to an integrated luminosity of 36.1 fb(-1). The results are interpreted in the context of various models where squarks and gluinos are pair produced and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.03 TeV for a simplified model incorporating only a gluino and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first-and second-generation squarks, squark masses below 1.55 TeVare excluded if the lightest neutralino is massless. These limits substantially extend the region of supersymmetric parameter space previously excluded by searches with the ATLAS detector.

  • 12. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Study of ordered hadron chains with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 9, artikel-id 092008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The analysis of the momentum difference between charged hadrons in high-energy proton-proton collisions is performed in order to study coherent particle production. The observed correlation pattern agrees with a model of a helical QCD string fragmenting into a chain of ground-state hadrons. A threshold momentum difference in the production of adjacent pairs of charged hadrons is observed, in agreement with model predictions. The presence of low-mass hadron chains also explains the emergence of charge-combination-dependent two-particle correlations commonly attributed to Bose-Einstein interference. The data sample consists of 190 mu b(-1) of minimum-bias events collected with proton-proton collisions at a center-of-mass energy root s = 7 TeV in the early low-luminosity data taking with the ATLAS detector at the LHC.

  • 13. Aaboud, M.
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Measurement of the t(t)over-bar production cross section in the tau plus jets final state in pp collisions at root s=8 TeV using the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 7, artikel-id 072003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A measurement of the inclusive pp -> t (t) over bar + X production cross section in the tau + jets final state using only the hadronic decays of the tau lepton is presented. The measurement is performed using 20.2 fb(-1) of proton-proton collision data recorded at a center-of-mass energy of root s = 8 TeV with the ATLAS detector at the Large Hadron Collider. The cross section is measured via a counting experiment by imposing a set of selection criteria on the identification and kinematic variables of the reconstructed particles and jets, and on event kinematic variables and characteristics. The production cross section is measured to be sigma(t (t) over bar) = 239 +/- 29 pb, which is in agreement with the measurements in other final states and the theoretical predictions at this center-of-mass energy.

  • 14. Aaboud, M
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for anomalous electroweak production of WW/WZ in association with a high-mass dijet system in pp collisions at root S=8 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 3, artikel-id 032001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search is presented for anomalous quartic gauge boson couplings in vector-boson scattering. The data for the analysis correspond to 20.2 fb(-1) of root S = 8 TeV pp collisions and were collected in 2012 by the ATLAS experiment at the Large Hadron Collider. The search looks for the production ofWW or WZ boson pairs accompanied by a high-mass dijet system, with one W decaying leptonically and a W or Z decaying hadronically. The hadronically decaying W/Z is reconstructed as either two small-radius jets or one largeradius jet using jet substructure techniques. Constraints on the anomalous quartic gauge boson coupling parameters a 4 and a 5 are set by fitting the transverse mass of the diboson system, and the resulting 95% confidence intervals are -0.024 < alpha(4) < 0.030 and -0.028 < alpha(5) < 0.033.

  • 15. Aaboud, M.
    et al.
    Kastanas, Konstatinos
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Jet energy scale measurements and their systematic uncertainties in proton-proton collisions at root s=13 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 7, artikel-id 072002Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of root s = 13 TeV, corresponding to an integrated luminosity of 3.2 fb(-1) collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-k(t) algorithm with radius parameter R = 0.4. Jets are calibrated with a series of simulation-based corrections and in situ techniques. In situ techniques exploit the transverse momentum balance between a jet and a reference object such as a photon, Z boson, or multijet system for jets with 20 < p(T) < 2000 GeV and pseudorapidities of vertical bar eta vertical bar < 4.5, using both data and simulation. An uncertainty in the jet energy scale of less than 1% is found in the central calorimeter region (vertical bar eta vertical bar < 1.2) for jets with 100 < p(T) < 500 GeV. An uncertainty of about 4.5% is found for low-p(T) jets with p(T) = 20 GeV in the central region, dominated by uncertainties in the corrections for multiple proton-proton interactions. The calibration of forward jets (vertical bar eta vertical bar > 0.8) is derived from dijet p(T) balance measurements. For jets of p(T) = 80 GeV, the additional uncertainty for the forward jet calibration reaches its largest value of about 2% in the range vertical bar eta vertical bar > 3.5 and in a narrow slice of 2.2 < vertical bar eta vertical bar < 2.4.

  • 16. Aaboud, M.
    et al.
    Kastanas, Konstatinos
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for new phenomena in dijet events using 37 fb(-1) of pp collision data collected at root s=13 TeV with the ATLAS detector2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 5, artikel-id 052004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of 3.5 fb(-1) and 33.5 fb(-1) respectively. Invariant mass and angular distributions are compared to background predictions and no significant deviation is observed. For resonance searches, a new method for fitting the background component of the invariant mass distribution is employed. The dataset is then used to set upper limits at a 95% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy W' bosons, W* bosons, and a range of masses and couplings in a Z' dark matter mediator model. Model-independent limits on signals with a Gaussian shape are also set, using a new approach allowing factorization of physics and detector effects. From the angular distributions, a scale of new physics in contact interaction models is excluded for scenarios with either constructive or destructive interference. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.

  • 17.
    Aaboud, M
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco..
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland.
    et al.,
    Search for photonic signatures of gauge-mediated supersymmetry in 13 TeV pp collisions with the ATLAS detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 9, artikel-id 092006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search is presented for photonic signatures, motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 36.1 fb(-1) recorded by the ATLAS detector at the LHC, and it explores models dominated by both strong and electroweak production of supersymmetric partner states. Experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon or additional jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction, and 95% confidence-level upper limits of between 0.083 and 0.32 fb are set on the visible cross section of contributions from physics beyond the Standard Model. These results are interpreted in terms of lower limits on the masses of gluinos, squarks, and gauginos in the context of generalized models of gauge-mediated supersymmetry, which reach as high as 2.3 TeV for strongly produced and 1.3 TeV for weakly produced supersymmetric partner pairs.

  • 18. Aaboud, M.
    et al.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for top squarks in final states with one isolated lepton, jets, and missing transverse momentum in root s=13 TeV pp collisions with the ATLAS detector2016Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 94, nr 5, artikel-id 052009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The results of a search for the top squark, the supersymmetric partner of the top quark, in final states with one isolated electron or muon, jets, and missing transverse momentum are reported. The search uses the 2015 LHC pp collision data at a center-of-mass energy of root s = 13 TeV recorded by the ATLAS detector and corresponding to an integrated luminosity of 3.2 fb(-1). The analysis targets two types of signal models: gluino-mediated pair production of top squarks with a nearly mass-degenerate top squark and neutralino and direct pair production of top squarks, decaying to the top quark and the lightest neutralino. The experimental signature in both signal scenarios is similar to that of a top quark pair produced in association with large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits on gluino and top squark masses are set at 95% confidence level. The results extend the LHC run-1 exclusion limit on the gluino mass up to 1460 GeV in the gluino-mediated scenario in the high gluino and low top squark mass region and add an excluded top squark mass region from 745 to 780 GeV for the direct top squark model with a massless lightest neutralino. The results are also reinterpreted to set exclusion limits in a model of vectorlike top quarks.

  • 19. Alonso, D.
    et al.
    Bellini, E.
    Ferreira, P. G.
    Zumalacarregui, Miguel
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Sweden.
    Observational future of cosmological scalar-tensor theories2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 6, artikel-id 063502Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The next generation of surveys will greatly improve our knowledge of cosmological gravity. In this paper we focus on how Stage IV photometric redshift surveys, including weak lensing and multiple tracers of the matter distribution and radio experiments combined with measurements of the cosmic microwave background will lead to precision constraints on deviations from general relativity. We use a broad subclass of Horndeski scalar-tensor theories to forecast the accuracy with which we will be able to determine these deviations and their degeneracies with other cosmological parameters. Our analysis includes relativistic effects, does not rely on the quasistatic evolution and makes conservative assumptions about the effect of screening on small scales. We define a figure of merit for cosmological tests of gravity and show how the combination of different types of surveys, probing different length scales and redshifts, can be used to pin down constraints on the gravitational physics to better than a few percent, roughly an order of magnitude better than present probes. Future cosmological experiments will be able to constrain

  • 20. Amoretti, A.
    et al.
    Areán, D.
    Goutéraux, Blaise
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Musso, D.
    Effective holographic theory of charge density waves2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 8, artikel-id 086017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use gauge/gravity duality to write down an effective low energy holographic theory of charge density waves. We consider a simple gravity model which breaks translations spontaneously in the dual field theory in a homogeneous manner, capturing the low energy dynamics of phonons coupled to conserved currents. We first focus on the leading two-derivative action, which leads to excited states with nonzero strain. We show that including subleading quartic derivative terms leads to dynamical instabilities of AdS2 translation invariant states and to stable phases breaking translations spontaneously. We compute analytically the real part of the electric conductivity. The model allows to construct Lifshitz-like hyperscaling violating quantum critical ground states breaking translations spontaneously. At these critical points, the real part of the dc conductivity can be metallic or insulating.

  • 21.
    Anastasiou, Alexandros
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Borsten, L.
    Duff, M. J.
    Hughes, M. J.
    Marrani, A.
    Nagy, S.
    Zoccali, M.
    Twin supergravities from Yang-Mills theory squared2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 2, artikel-id 026013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider "twin supergravities"-pairs of supergravities with N+ and N- supersymmetries, N+ > N-, with identical bosonic sectors-in the context of tensoring super Yang-Mills multiplets. It is demonstrated that the pairs of twin supergravity theories are related through their left and right super YangMills factors. This procedure generates newtheories from old ones. In particular, the matter coupled N(-)twins in D = 3, 5, 6 and the N- = 1 twins inD = 4 have not, as far as we are aware, been obtained previously using the double-copy construction, adding to the growing list of double-copy constructible theories. The use of fundamental matter multiplets in the double-copy construction leads us to introduce a bifundamental scalar that couples to the well-known biadjoint scalar field. It is also shown that certain matter coupled supergravities admit more than one factorization into left and right super Yang-Mills-matter theories.

  • 22.
    Baum, Sebastian
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
    Freese, Katherine
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. University of Michigan, United States; Stockholm University, Sweden.
    Shah, N. R.
    Shakya, B.
    NMSSM Higgs boson search strategies at the LHC and the mono-Higgs signature in particular2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 11, artikel-id 115036Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the collider phenomenology of the extended Higgs sector of the next-to-minimal supersymmetric Standard Model (NMSSM). The region of NMSSM parameter space favored by a 125 GeV SM-like Higgs and naturalness generically features a light Higgs and neutralino spectrum as well as a large O(1) coupling between the Higgs doublets and the NMSSM singlet fields. In such regimes, the heavier Higgs bosons can decay dominantly into lighter Higgs bosons and neutralinos. We study the prospects of observing such decays at the 13 TeV LHC, focusing on mono-Higgs signatures as probes of such regions of parameter space. We present results for the mono-Higgs reach in a framework easily applicable to other models featuring similar decay topologies. In the NMSSM, we find that the mono-Higgs channel can probe TeV scale Higgs bosons and has sensitivity even in the low tanβ, large mA regime that is difficult to probe in the MSSM. Unlike for many conventional Higgs searches, the reach of the mono-Higgs channel will improve significantly with the increased luminosity expected to be collected at the LHC in the ongoing and upcoming runs.

  • 23.
    Baum, Sebastian
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Visinelli, Luca
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Freese, Katherine
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Stengel, Patrick
    Dark matter capture, subdominant WIMPs, and neutrino observatories2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 4, artikel-id 043007Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Weakly interacting massive particles (WIMPs), which are among the best motivated dark matter (DM) candidates, could make up all or only a fraction of the total DM budget. We consider a scenario in which WIMPs are a subdominant DM component; such a scenario would affect both current direct and indirect bounds on the WIMP-nucleon scattering cross section. In this paper we focus on indirect searches for the neutrino flux produced by annihilation of subdominant WIMPs captured by the Sun or the Earth via either spin-dependent or spin-independent scattering. We derive the annihilation rate and the expected neutrino flux at neutrino observatories. In our computation, we include an updated chemical composition of the Earth with respect to the previous literature, leading to an increase of the Earth's capture rate for spin-dependent scattering by a factor of 3. Results are compared with current bounds from Super-Kamiokande and IceCube. We discuss the scaling of bounds from both direct and indirect detection methods with the WIMP abundance.

  • 24. Baym, Gordon
    et al.
    Patil, Subodh P.
    Pethick, Christopher
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. University of Copenhagen, Denmark.
    Damping of gravitational waves by matter2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 8, artikel-id 084033Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We develop a unified description, via the Boltzmann equation, of damping of gravitational waves by matter, incorporating collisions. We identify two physically distinct damping mechanisms-collisional and Landau damping. We first consider damping in flat spacetime, and then generalize the results to allow for cosmological expansion. In the first regime, maximal collisional damping of a gravitational wave, independent of the details of the collisions in the matter is, as we show, significant only when its wavelength is comparable to the size of the horizon. Thus damping by intergalactic or interstellar matter for all but primordial gravitational radiation can be neglected. Although collisions in matter lead to a shear viscosity, they also act to erase anisotropic stresses, thus suppressing the damping of gravitational waves. Damping of primordial gravitational waves remains possible. We generalize Weinberg's calculation of gravitational wave damping, now including collisions and particles of finite mass, and interpret the collisionless limit in terms of Landau damping. While Landau damping of gravitational waves cannot occur in flat spacetime, the expansion of the universe allows such damping by spreading the frequency of a gravitational wave of given wave vector.

  • 25. Bellini, E.
    et al.
    Barreira, A.
    Frusciante, N.
    Hu, B.
    Peirone, S.
    Raveri, M.
    Zumalacarregui, Miguel
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Avilez-Lopez, A.
    Ballardini, M.
    Battye, R. A.
    Bolliet, B.
    Calabrese, E.
    Dirian, Y.
    Ferreira, P. G.
    Finelli, F.
    Huang, Z.
    Ivanov, M. M.
    Lesgourgues, J.
    Li, B.
    Lima, N. A.
    Pace, F.
    Paoletti, D.
    Sawicki, I.
    Silvestri, A.
    Skordis, C.
    Umilta, C.
    Vernizzi, F.
    Comparison of Einstein-Boltzmann solvers for testing general relativity2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 2, artikel-id 023520Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compare Einstein-Boltzmann solvers that include modifications to general relativity and find that, for a wide range of models and parameters, they agree to a high level of precision. We look at three general purpose codes that primarily model general scalar-tensor theories, three codes that model Jordan-Brans-Dicke (JBD) gravity, a code that models f(R) gravity, a code that models covariant Galileons, a code that models Horava-Lifschitz gravity, and two codes that model nonlocal models of gravity. Comparing predictions of the angular power spectrum of the cosmic microwave background and the power spectrum of dark matter for a suite of different models, we find agreement at the subpercent level. This means that this suite of Einstein-Boltzmann solvers is now sufficiently accurate for precision constraints on cosmological and gravitational parameters.

  • 26.
    Beltran Jimenez, Jose
    et al.
    Univ Autonoma Madrid, Inst Fis Teor, UAM CSIC, E-28049 Madrid, Spain.;Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain..
    Heisenberg, Lavinia
    Swiss Fed Inst Technol, Inst Theoret Studies, Clausiusstr 47, CH-8092 Zurich, Switzerland..
    Koivisto, Tomi S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Coincident general relativity2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 4, artikel-id 044048Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The metric-affine variational principle is applied to generate teleparallel and symmetric teleparallel theories of gravity. From the latter we discover an exceptional class which is consistent with a vanishing affine connection. Based on this remarkable property, this work proposes a simpler geometrical formulation of general relativity that is oblivious to the affine spacetime structure, thus fundamentally depriving gravity of any inertial character. The resulting theory is described by the Hilbert action purged from the boundary term and is more robustly underpinned by the spin-2 field theory, where an extra symmetry is now manifest, possibly related to the double-copy structure of the gravity amplitudes. This construction also provides a novel starting point for modified gravity theories, and the paper presents new and simple generalizations where analytical self-accelerating cosmological solutions arise naturally in the early-and late-time Universe.

  • 27.
    Bern, Zvi
    et al.
    Univ Calif Los Angeles, Mani L Bhaumik Inst Theoret Phys, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Carrasco, John Joseph
    Univ Paris Saclay, CEA Saclay, Inst Theoret Phys, F-91191 Gif Sur Yvette, France.;CNRS, F-91191 Gif Sur Yvette, France..
    Chen, Wei-Ming
    Univ Calif Los Angeles, Mani L Bhaumik Inst Theoret Phys, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Edison, Alex
    Univ Calif Los Angeles, Mani L Bhaumik Inst Theoret Phys, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Johansson, Karl H.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Uppsala Univ, Dept Phys & Astron, S-75108 Uppsala, Sweden..
    Parra-Martinez, Julio
    Univ Calif Los Angeles, Mani L Bhaumik Inst Theoret Phys, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Roiban, Radu
    Penn State Univ, Inst Gravitat & Cosmos, University Pk, PA 16802 USA..
    Zeng, Mao
    Univ Calif Los Angeles, Mani L Bhaumik Inst Theoret Phys, Dept Phys & Astron, Los Angeles, CA 90095 USA..
    Ultraviolet properties of N=8 supergravity at five loops2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 8, artikel-id 086021Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use the recently developed generalized double-copy construction to obtain an improved representation of the five-loop four-point integrand of N = 8 supergravity whose leading ultraviolet behavior we analyze using state-of-the-art loop-integral expansion and reduction methods. We find that the five-loop critical dimension where ultraviolet divergences first occur is D-c = 24/5, corresponding to a (DR4)-R-8 counterterm. This ultraviolet behavior stands in contrast to the cases of four-dimensional N = 4 supergravity at three loops and N = 5 supergravity at four loops whose improved ultraviolet behavior demonstrates enhanced cancellations beyond implications from standard symmetry considerations. We express this D-c = 24/5 divergence in terms of two relatively simple positive-definite integrals with vanishing external momenta, excluding any additional ultraviolet cancellations at this loop order. We note nontrivial relations between the integrals describing this leading ultraviolet behavior and integrals describing lower-loop behavior. This observation suggests not only a path towards greatly simplifying future calculations at higher loops, but may even allow us to directly investigate ultraviolet behavior in terms of simplified integrals, avoiding the construction of complete integrands.

  • 28. Bern, Zvi
    et al.
    Carrasco, John Joseph
    Chen, Wei-Ming
    Johansson, Henrik
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Roiban, Radu
    Zeng, Mao
    Five-loop four-point integrand of N=8 supergravity as a generalized double copy2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 12, artikel-id 126012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use the recently developed generalized double-copy procedure to construct an integrand for the fiveloop four-point amplitude of N = 8 supergravity. This construction starts from a naive double copy of the previously computed corresponding amplitude of N = 4 super-Yang-Mills theory. This is then systematically modified by adding contact terms generated in the context of the method of maximal unitarity cuts. For the simpler generalized cuts, whose corresponding contact terms tend to be the most complicated, we derive a set of formulas relating the contact contributions to the violations of the dual Jacobi identities in the relevant gauge-theory amplitudes. For more complex generalized unitarity cuts, which tend to have simpler contact terms associated with them, we use the method of maximal cuts more directly. The five-loop fourpoint integrand is a crucial ingredient towards future studies of ultraviolet properties of N = 8 supergravity at five loops and beyond. We also present a nontrivial check of the consistency of the integrand, based on modern approaches for integrating over the loop momenta in the ultraviolet region.

  • 29. Bernard, Laura
    et al.
    Deffayet, Cedric
    Hinterbichler, Kurt
    von Strauss, Mikael
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. UPMC, France.
    Partially massless graviton on beyond Einstein spacetimes2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 12, artikel-id 124036Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that a partially massless graviton can propagate on a large set of spacetimes which are not Einstein spacetimes. Starting from a recently constructed theory for a massive graviton that propagates the correct number of degrees of freedom on an arbitrary spacetime, we first give the full explicit form of the scalar constraint responsible for the absence of a sixth degree of freedom. We then spell out generic conditions for the constraint to be identically satisfied, so that there is a scalar gauge symmetry which makes the graviton partially massless. These simplify if one assumes that spacetime is Ricci symmetric. Under this assumption, we find explicit non-Einstein spacetimes (some, but not all, with vanishing Bach tensors) allowing for the propagation of a partially massless graviton. These include in particular the Einstein static Universe.

  • 30.
    Bettoni, Dario
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Sweden.
    Ezquiaga, Jose Maria
    Hinterbichler, Kurt
    Zumalacarregui, Miguel
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Sweden; Univ Calif Berkeley, USA.
    Speed of gravitational waves and the fate of scalar-tensor gravity2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 8, artikel-id 084029Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The direct detection of gravitational waves (GWs) is an invaluable new tool to probe gravity and the nature of cosmic acceleration. A large class of scalar-tensor theories predicts that GWs propagate with velocity different than the speed of light, a difference that can be O(1) for many models of dark energy. We determine the conditions behind the anomalous GW speed, namely, that the scalar field spontaneously breaks Lorentz invariance and couples to the metric perturbations via the Weyl tensor. If these conditions are realized in nature, the delay between GW and electromagnetic signals from distant events will run beyond human time scales, making it impossible to measure the speed of GWs using neutron star mergers or other violent events. We present a robust strategy to exclude or confirm an anomalous speed of GWs using eclipsing binary systems, the electromagnetic phase of which can be exquisitely determined. The white dwarf binary J0651 + 2844 is a known example of such a system that can be used to probe deviations in the GW speed as small as cg/ c - 1 greater than or similar to 2 x 10(-12) when LISA comes online. This test will either eliminate many contender models for cosmic acceleration or wreck a fundamental pillar of general relativity.

  • 31.
    Borsato, R.
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Strömwall, J.
    Torrielli, A.
    Q -Poincaré invariance of the AdS3 /CFT2 R -matrix2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 6, artikel-id 066001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the exact R-matrix of AdS3/CFT2, which is the building block for describing the scattering of worldsheet excitations of the light-cone gauge-fixed backgrounds AdS3×S3×T4 and AdS3×S3×S3×S1 with pure Ramond-Ramond fluxes. We show that R is invariant under a "deformed boost" symmetry, for which we write an explicit exact coproduct, i.e. its action on two-particle states. When we include the boost, the symmetries of the R-matrix close into a q-Poincaré superalgebra. Our findings suggest that the recently discovered boost invariance in AdS5/CFT4 may be a common feature of AdS/CFT systems that are treatable with the exact techniques of integrability. With the aim of going towards a universal formulation of the underlying Hopf algebra, we also propose a universal form of the AdS3/CFT2 classical r-matrix. 

  • 32.
    Boucenna, Sofiane M.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Shafi, Qaisar
    Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA..
    Axion inflation, proton decay, and leptogenesis in SU (5) x U(1)(PQ)2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 7, artikel-id 075012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We implement inflation in a nonsupersymmetric SU(5) model based on a nonminimal coupling of the axion field to gravity. The isocurvature fluctuations are adequately suppressed, axions comprise the dark matter, proton lifetime estimates are of order 8 x 10(34)-3 x 10(35) yr, and the observed baryon asymmetry arises via nonthermal leptogenesis. The presence of low-scale colored scalars ensures unification of the Standard Model gauge couplings and also helps in stabilizing the electroweak vacuum.

  • 33.
    Brandenburg, Axel
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
    Kahniashvili, Tina
    Mandal, Sayan
    Pol, Alberto Roper
    Tevzadze, Alexander G.
    Vachaspati, Tanmay
    Evolution of hydromagnetic turbulence from the electroweak phase transition2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 12, artikel-id 123528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present new simulations of decaying hydromagnetic turbulence for a relativistic equation of state relevant to the early Universe. We compare helical and nonhelical cases either with kinetically or magnetically dominated initial fields. Both kinetic and magnetic initial helicities lead to maximally helical magnetic fields after some time, but with different temporal decay laws. Both are relevant to the early Universe, although no mechanisms have yet been identified that produce magnetic helicity with strengths comparable to the big bang nucleosynthesis limit at scales comparable to the Hubble horizon at the electroweak phase transition. Nonhelical magnetically dominated fields could still produce picoGauss magnetic fields under most optimistic conditions. Only helical magnetic fields can potentially have nanoGauss strengths at scales up to 30 kpc today.

  • 34.
    Chen, Hui-Huang
    et al.
    Jiangxi Normal Univ, Coll Phys & Commun Elect, Nanchang 330022, Jiangxi, Peoples R China..
    Ouyang, Hao
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Wu, Jun-Bao
    Tianjin Univ, Ctr Joint Quantum Studies, 135 Yaguan Rd, Tianjin 300350, Peoples R China.;Tianjin Univ, Dept Phys, Sch Sci, 135 Yaguan Rd, Tianjin 300350, Peoples R China.;Peking Univ, Ctr High Energy Phys, 5 Yiheyuan Rd, Beijing 100871, Peoples R China..
    Open spin chains from determinant like operators in ABJM theory2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 10, artikel-id 106012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the mixing problem of the determinantlike operators in ABJM theory to two-loop order in the scalar sector. The gravity duals of these operators are open strings attached to the maximal giant graviton, which is a D4-brane wrapping a CP2 inside CP3 in our case. The anomalous dimension matrix of these operators can be regarded as an open spin chain Hamiltonian. We provide strong evidence of its integrability based on coordinate Bethe ansatz method and boundary Yang-Baxter equations.

  • 35.
    Choubey, Sandhya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Harish-Chandra Research Institute, India.
    Dutta, Debajyoti
    Pramanik, Dipyaman
    Imprints of a light sterile neutrino at DUNE, T2HK, and T2HKK2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 5, artikel-id 056026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We evaluate the impact of sterile neutrino oscillations in the so-called 3 + 1 scenario on the proposed long baseline experiment in USA and Japan. There are two proposals for the Japan experiment which are called T2HK and T2HKK. We show the impact of sterile neutrino oscillation parameters on the expected sensitivity of T2HK and T2HKK to mass hierarchy, CP violation and octant of theta(23) and compare it against that expected in the case of standard oscillations. We add the expected ten years data from DUNE and present the combined expected sensitivity of T2HKK + DUNE to the oscillation parameters. We do a full marginalization over the relevant parameter space and show the effect of the magnitude of the true sterile mixing angles on the physics reach of these experiments. We show that if one assumes that the source of CP violation is the standard CP phase alone in the test case, then it appears that the expected CP violation sensitivity decreases due to sterile neutrinos. However, if we give up this assumption, then the CP sensitivity could go in either direction. The impact on expected octant of theta(23) and mass hierarchy sensitivity is shown to depend on the magnitude of the sterile mixing angles in a nontrivial way.

  • 36.
    Choubey, Sandhya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Goswami, Srubabati
    Gupta, Chandan
    Lakshmi, S. M.
    Thakore, Tarak
    Sensitivity to neutrino decay with atmospheric neutrinos at the INO-ICAL detector2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 3, artikel-id 033005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sensitivity of the magnetized Iron Calorimeter (ICAL) detector at the proposed India-based Neutrino Observatory (INO) to invisible decay of the mass eigenstate nu(3) using atmospheric neutrinos is explored. A full three-generation analysis including Earth matter effects is performed in a framework with both decay and oscillations. The wide energy range and baselines offered by atmospheric neutrinos are shown to be excellent for constraining the nu(3) lifetime. We find that with an exposure of 500 kton - yr the ICAL atmospheric experiment could constrain the. 3 lifetime to tau(3)/m(3) > 1.51 x 10(-10) s/eV at the 90% C.L. This is 2 orders of magnitude tighter than the bound from MINOS. The effect of invisible decay on the precision measurement of theta(23) and vertical bar Delta m(32)(2)vertical bar is also studied.

  • 37.
    De Jonckheere, Tim
    et al.
    Vrije Univ Brussel, Theoret Nat Kunde, Pl Laan 2, B-1050 Brussels, Belgium.;Int Solvay Inst, Pl Laan 2, B-1050 Brussels, Belgium..
    Lindgren, Jonathan
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden..
    Entanglement entropy in inhomogeneous quenches in AdS(3)/CFT22018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 10, artikel-id 106006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compute entanglement entropy and differential entropy in inhomogeneous holographic quenches in AdS(3)/CFT2. The quenches are arbitrarily inhomogeneous and modeled by an infalling shell of massless nonrotating matter where the final state is not dual to a static black hole but rather to a black hole with time-dependent stress-energy tensor modes. We study the entanglement entropy of an interval and differential entropy of a family of intervals analytically when the inhomogeneities have a perturbative amplitude and numerically for nonperturbative inhomogeneities. While we are in principle able to study these quantities for any inhomogeneities, we discuss two concrete examples: an oscillatory quench and a bilocal quench. Both cases display saturation towards a steady state but do not fully thermalize. Depending on the location and size of the interval, the entanglement entropy displays a variety of interesting phenomena such as plateau phases, bumps, and discontinuities in its first derivative with respect to time.

  • 38.
    Harko, Tiberiu
    et al.
    Babes Bolyai Univ, Dept Phys, Kogalniceanu St, Cluj Napoca 400084, Romania.;Sun Yat Sen Univ, Sch Phys, Guangzhou 510275, Guangdong, Peoples R China.;UCL, Dept Math, Gower St, London W E 6BT, England..
    Koivisto, Tomi S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. KTH Royal Inst Technol, Nordita, Roslagstullsbacken 23, S-10691 Stockholm, Sweden.;Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden..
    Lobo, Francisco S. N.
    Univ Lisbon, Fac Ciencias, Inst Astrofis & Ciencias Espaco, Edificio C8, P-1749016 Lisbon, Portugal.;Univ Lisbon, Fac Ciencias, Dept Fis, Edificio C8, P-1749016 Lisbon, Portugal..
    Olmo, Gonzalo J.
    Univ Valencia, CSIC, Ctr Mixto Univ Valencia, Dept Fis Teor, E-46100 Valencia, Spain.;Univ Valencia, CSIC, Ctr Mixto Univ Valencia, IFIC, E-46100 Valencia, Spain.;Univ Fed Paraiba, Dept Fis, BR-58051900 Joao Pessoa, Paraiba, Brazil..
    Rubiera-Garcia, Diego
    Univ Lisbon, Fac Ciencias, Inst Astrofis & Ciencias Espaco, Edificio C8, P-1749016 Lisbon, Portugal..
    Coupling matter in modified Q gravity2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 8, artikel-id 084043Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a novel theory of gravity by considering an extension of symmetric teleparallel gravity. This is done by introducing, in the framework of the metric-affine formalism, a new class of theories where the nonmetricity Q is nonminimally coupled to the matter Lagrangian. More specifically, we consider a Lagrangian of the form L similar to f(1)(Q) + f(2)(Q)L-M, where f(1) and f(2) are generic functions of Q, and L-M is the matter Lagrangian. This nonminimal coupling entails the nonconservation of the energy-momentum tensor, and consequently the appearance of an extra force. The formulation of the gravity sector in terms of the Q instead of the curvature may result in subtle improvements of the theory. In the context of nonminimal matter couplings, we are therefore motivated to explore whether the new geometrical formulation in terms of the Q, when implemented also in the matter sector, would allow more universally consistent and viable realizations of the nonminimal coupling. Furthermore, we consider several cosmological applications by presenting the evolution equations and imposing specific functional forms of the functions f(1)(Q) and f(2)(Q), such as power-law and exponential dependencies of the nonminimal couplings. Cosmological solutions are considered in two general classes of models, and found to feature accelerating expansion at late times.

  • 39.
    Huang, Guo-yuan
    et al.
    Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100049, Peoples R China..
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Teoretisk partikelfysik. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Zhou, Shun
    Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;Univ Chinese Acad Sci, Sch Phys Sci, Beijing 100049, Peoples R China.;Peking Univ, Ctr High Energy Phys, Beijing 100871, Peoples R China..
    Observational constraints on secret neutrino interactions from big bang nucleosynthesis2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 7, artikel-id 075009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate possible interactions between neutrinos and massive scalar bosons via g(phi)(nu) over bar nu phi (or massive vector bosons via g(V)(nu) over bar gamma(mu)nu V-mu) and explore the allowed parameter space of the coupling constant g phi (or g(V)) and the scalar (or vector) boson mass m(phi) (or m(V)) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of big bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on g(phi) and m(phi) in the scalar-boson case is rather weak, due to a small number of degrees of freedom (d.o.f.). However, in the vector-boson case, the most stringent bound on the coupling g(V) less than or similar to 6 x 10(-10) at 95% confidence level is obtained for m(V) similar or equal to 1 MeV, while the bound becomes much weaker g(V) less than or similar to 8 x 10(-6) for smaller masses m(V) less than or similar to 10(-4) MeV. Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.

  • 40.
    Kuhnel, Florian
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Teoretisk partikelfysik. Stockholm Univ, Sweden.
    Freese, Katherine
    Constraints on primordial black holes with extended mass functions2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 8, artikel-id 083508Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Constraints on primordial black holes in the range 10(-18) M circle dot to 10(3) M circle dot are reevaluated for a general class of extended mass functions. Whereas previous work has assumed that PBHs are produced with one single mass, instead there is expected to be a range of masses even in the case of production from a single mechanism; constraints therefore change from previous literature. Although tightly constrained in the majority of cases, it is shown that, even under conservative assumptions, primordial black holes in the mass range 10(-10) M circle dot to 10(-8) M circle dot could still constitute the entirety of the dark matter. This stresses both the importance for a comprehensive reevaluation of all respective constraints that have previously been evaluated only for a monochromatic mass function and the need to obtain more constraints in the allowed mass range.

  • 41.
    Kuhnel, Florian
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Teoretisk partikelfysik. AlbaNova University Center, Sweden.
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Teoretisk partikelfysik. AlbaNova University Center, Sweden; University of Iceland, Iceland.
    Signatures of compact halos of sterile-neutrino dark matter2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 10, artikel-id 103020Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate compact halos of sterile-neutrino dark matter and examine observable signatures with respect to neutrino and photon emission. Primarily, we consider two cases: primordial black-hole halos and ultracompact minihalos. In both cases, we find that there exists a broad range of possible parameter choices such that detection in the near future with x-ray and gamma-ray telescopes might be well possible. In fact, for energies above 10 TeV, the neutrino telescope IceCube would be a splendid detection machine for such macroscopic dark-matter candidates.

  • 42. Maria Ezquiaga, Jose
    et al.
    Garcia-Bellido, Juan
    Zumalacarregui, Miguel
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Field redefinitions in theories beyond Einstein gravity using the language of differential forms2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 8, artikel-id 084039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the role of field redefinitions in general scalar-tensor theories. In particular, we first focus on the class of field redefinitions linear in the spin-2 field and involving derivatives of the spin-0 mode, generically known as disformal transformations. We start by defining the action of a disformal transformation in the tangent space. Then, we take advantage of the great economy of means of the language of differential forms to compute the full transformation of Horndeski's theory under general disformal transformations. We obtain that Horndeski's action maps onto itself modulo a reduced set of non-Horndeski Lagrangians. These new Lagrangians are found to be invariant under disformal transformation that depend only in the first derivatives of the scalar. Moreover, these combinations of Lagrangians precisely appear when expressing in our basis the constraints of the recently proposed extended scalar-tensor theories. These results allow us to classify the different orbits of scalar-tensor theories invariant under particular disformal transformations, namely, the special disformal, kinetic disformal, and disformal Horndeski orbits. In addition, we consider generalizations of this framework. We find that there are possible well-defined extended disformal transformations that have not been considered in the literature. However, they generically cannot link Horndeski theory with extended scalar-tensor theories. Finally, we study further generalizations in which extra fields with different spin are included. These field redefinitions can be used to connect different gravity theories such as multiscalar-tensor theories, generalized Proca theories, and bigravity. We discuss how the formalism of differential forms could be useful for future developments in these lines.

  • 43. Nersisyan, Henrik
    et al.
    Akrami, Yashar
    Amendola, Luca
    Koivisto, Tomi S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Rubio, Javier
    Solomon, Adam R.
    Instabilities in tensorial nonlocal gravity2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 4, artikel-id 043539Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss the cosmological implications of nonlocal modifications of general relativity containing tensorial structures. Assuming the presence of standard radiation-and matter-dominated eras, we show that, except in very particular cases, the nonlocal terms contribute a rapidly growing energy density. These models therefore generically do not have a stable cosmological evolution.

  • 44.
    Porter, T. A.
    et al.
    Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA.;Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, Stanford, CA 94305 USA..
    Rowell, G. P.
    Univ Adelaide, Sch Phys Sci, Adelaide, SA 5000, Australia..
    Johannesson, Guolaugur
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Univ Iceland, Inst Sci, IS-107 Reykjavik, Iceland..
    Moskalenko, I. V.
    Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA.;Stanford Univ, Kavli Inst Particle Astrophys & Cosmol, Stanford, CA 94305 USA..
    Galactic PeVatrons and helping to find them: Effects of galactic absorption on the observed spectra of very high energy gamma-ray sources2018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, nr 4, artikel-id 041302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Identification of the cosmic-ray (CR) "PeVatrons," which are sources capable of accelerating particles to similar to 10(15) eV energies and higher, may lead to resolving the long-standing question of the origin of the spectral feature in the all-particle CR spectrum known as the "knee." Because CRs with these energies are deflected by interstellar magnetic fields identification of individual sources and determination of their spectral characteristics is more likely via very high energy gamma-ray emissions, which provide the necessary directional information. However, pair production on the interstellar radiation field (ISRF) and cosmic microwave background (CMB) leads to steepening of the high energy tails of gamma-ray spectra, and should be corrected for to enable true properties of the spectrum at the source to be recovered. Employing recently developed three-dimensional ISRF models this paper quantifies the pair-absorption effect on spectra for sources in the Galactic center (GC) direction at 8.5 and 23.5 kpc distances, with the latter corresponding to the far side of the Galactic stellar disc where it is expected that discrimination of spectral features >10 TeV is possible by the forthcoming Cherenkov Telescope Array (CTA). The estimates made suggest spectral cutoffs could be underestimated by factors of a few in the energy range so far sampled by TeV gamma-ray telescopes. As an example to illustrate this, the recent HESS measurements of diffuse gamma-ray emissions possibly associated with injection of CRs nearby Sgr A* are ISRF corrected, and estimates of the spectral cutoff are reevaluated. It is found that it could be higher by up to a factor of similar to 2, indicating that these emissions may be consistent with a CR accelerator with a spectral cutoff of at least 1 PeV at the 95% confidence level.

  • 45. Singh, B.
    et al.
    Erni, W.
    Krusche, B.
    Steinacher, M.
    Walford, N.
    Liu, H.
    Liu, Z.
    Liu, B.
    Shen, X.
    Wang, C.
    Zhao, J.
    Albrecht, M.
    Erlen, T.
    Fink, M.
    Heinsius, F. H.
    Held, T.
    Holtmann, T.
    Jasper, S.
    Keshk, I.
    Koch, H.
    Kopf, B.
    Kuhlmann, M.
    Kuemmel, M.
    Leiber, S.
    Mikirtychyants, M.
    Musiol, P.
    Mustafa, A.
    Pelizaeus, M.
    Pychy, J.
    Richter, M.
    Schnier, C.
    Schroeder, T.
    Sowa, C.
    Steinke, M.
    Triffterer, T.
    Wiedner, U.
    Ball, M.
    Beck, R.
    Hammann, C.
    Ketzer, B.
    Kube, M.
    Mahlberg, P.
    Rossbach, M.
    Schmidt, C.
    Schmitz, R.
    Thoma, U.
    Urban, M.
    Walther, D.
    Wendel, C.
    Wilson, A.
    Bianconi, A.
    Bragadireanu, M.
    Caprini, M.
    Pantea, D.
    Patel, B.
    Czyzycki, W.
    Domagala, M.
    Filo, G.
    Jaworowski, J.
    Krawczyk, M.
    Lisowski, E.
    Lisowski, F.
    Michalek, M.
    Poznanski, P.
    Plazek, J.
    Korcyl, K.
    Kozela, A.
    Kulessa, P.
    Lebiedowicz, P.
    Pysz, K.
    Schaefer, W.
    Szczurek, A.
    Fiutowski, T.
    Idzik, M.
    Mindur, B.
    Przyborowski, D.
    Swientek, K.
    Biernat, J.
    Kamys, B.
    Kistryn, S.
    Korcyl, G.
    Krzemien, W.
    Magiera, A.
    Moskal, P.
    Pyszniak, A.
    Rudy, Z.
    Salabura, P.
    Smyrski, J.
    Strzempek, P.
    Wronska, A.
    Augustin, I.
    Boehm, R.
    Lehmann, I.
    Marinescu, D. Nicmorus
    Schmitt, L.
    Varentsov, V.
    Al-Turany, M.
    Belias, A.
    Deppe, H.
    Veis, N. Divani
    Dzhygadlo, R.
    Ehret, A.
    Flemming, H.
    Gerhardt, A.
    Goetzen, K.
    Gromliuk, A.
    Gruber, L.
    Karabowicz, R.
    Kliemt, R.
    Krebs, M.
    Kurilla, U.
    Lehmann, D.
    Loechner, S.
    Luehning, J.
    Lynen, U.
    Orth, H.
    Patsyuk, M.
    Peters, K.
    Saito, T.
    Schepers, G.
    Schmidt, C. J.
    Schwarz, C.
    Schwiening, J.
    Taeschner, A.
    Traxler, M.
    Ugur, C.
    Voss, B.
    Wieczorek, P.
    Wilms, A.
    Zuehlsdorf, M.
    Abazov, V.
    Alexeev, G.
    Arefiev, V. A.
    Astakhov, V.
    Barabanov, M. Yu.
    Batyunya, B. V.
    Davydov, Y.
    Dodokhov, V. Kh.
    Efremov, A.
    Fechtchenko, A.
    Fedunov, A. G.
    Galoyan, A.
    Grigoryan, S.
    Koshurnikov, E. K.
    Lobanov, Y. Yu.
    Lobanov, V. I.
    Makarov, A. F.
    Malinina, L. V.
    Malyshev, V.
    Olshevskiy, A. G.
    Perevalova, E.
    Piskun, A. A.
    Pocheptsov, T.
    Pontecorvo, G.
    Rodionov, V.
    Rogov, Y.
    Salmin, R.
    Samartsev, A.
    Sapozhnikov, M. G.
    Shabratova, G.
    Skachkov, N. B.
    Skachkova, A. N.
    Strokovsky, E. A.
    Suleimanov, M.
    Teshev, R.
    Tokmenin, V.
    Uzhinsky, V.
    Vodopianov, A.
    Zaporozhets, S. A.
    Zhuravlev, N. I.
    Zinchenko, A.
    Zorin, A. G.
    Branford, D.
    Glazier, D.
    Watts, D.
    Boehm, M.
    Britting, A.
    Eyrich, W.
    Lehmann, A.
    Pfaffinger, M.
    Uhlig, F.
    Dobbs, S.
    Seth, K.
    Tomaradze, A.
    Xiao, T.
    Bettoni, D.
    Carassiti, V.
    Ramusino, A. Cotta
    Dalpiaz, P.
    Drago, A.
    Fioravanti, E.
    Garzia, I.
    Savrie, M.
    Akishina, V.
    Kisel, I.
    Kozlov, G.
    Pugach, M.
    Zyzak, M.
    Gianotti, P.
    Guaraldo, C.
    Lucherini, V.
    Bersani, A.
    Bracco, G.
    Macri, M.
    Parodi, R. F.
    Biguenko, K.
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    Bäck, Torbjörn
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Cederwall, Bo
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Makonyi, K.
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    Wojciechowski, M.
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    Suzuki, K.
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    Zmeskal, J.
    Semenov-Tian-Shansky, K. M.
    Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0)2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, nr 3, artikel-id 032003Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is shown that the measurement can be done at (P) over bar ANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.

  • 46.
    Visinelli, Luca
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Light axion-like dark matter must be present during inflation2017Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, nr 2, artikel-id 023013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Axion-like particles (ALPs) might constitute the totality of the cold dark matter (CDM) observed. The parameter space of ALPs depends on the mass of the particle m and on the energy scale of inflation HI, the latter being bound by the nondetection of primordial gravitational waves. We show that the bound on HI implies the existence of a mass scale mχ=10 neV-0.5 peV, depending on the ALP susceptibility χ, such that the energy density of ALPs of mass smaller than mχ is too low to explain the present CDM budget, if the ALP field has originated after the end of inflation. This bound affects ultra-light axions (ULAs), which have recently regained popularity as CDM candidates. Light (m<mχ) ALPs can then be CDM candidates only if the ALP field has already originated during the inflationary period, in which case the parameter space is constrained by the nondetection of axion isocurvature fluctuations. We comment on the effects on these bounds from additional physics beyond the standard model, besides ALPs.

  • 47.
    Visinelli, Luca
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Bolis, Nadia
    Fyzikalni Ustav Akad CR, Cent European Inst Cosmol & Fundamental Phys CEIC, Na Slovance 1999-2, CZ-18221 Prague 8, Czech Republic..
    Vagnozzi, Sunny
    Stockholm Univ, Dept Phys, Oskar Klein Ctr Cosmoparticle Phys, AlbaNova Univ Ctr, Roslagstullbacken 21A, SE-10691 Stockholm, Sweden..
    Brane-world extra dimensions in light of GW1708172018Ingår i: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, nr 6, artikel-id 064039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The search for extra dimensions is a challenging endeavor to probe physics beyond the Standard Model. The joint detection of gravitational waves (GW) and electromagnetic (EM) signals from the merging of a binary system of compact objects like neutron stars can help constrain the geometry of extra dimensions beyond our 3 + 1 spacetime ones. A theoretically well-motivated possibility is that our observable Universe is a 3 + 1-dimensional hypersurface, or brane, embedded in a higher 4 + 1-dimensional antide Sitter (AdS(5)) spacetime, in which gravity is the only force which propagates through the infinite bulk space, while other forces are confined to the brane. In these types of brane-world models, GW and EM signals between two points on the brane would, in general, travel different paths. This would result in a time lag between the detection of GW and EM signals emitted simultaneously from the same source. We consider the recent near-simultaneous detection of the GW event GW170817 from the LIGO/Virgo collaboration, and its EM counterpart, the short gamma-ray burst GRB170817A detected by the Fermi Gamma-ray Burst Monitor and the International Gamma-Ray Astrophysics Laboratory Anti-Coincidence Shield spectrometer. Assuming the standard.-cold dark matter scenario and performing a likelihood analysis which takes into account astrophysical uncertainties associated to the measured time lag, we set an upper limit of l less than or similar to 0.535 Mpc at 68% confidence level on the AdS(5) radius of curvature l. Although the bound is not competitive with current Solar System constraints, it is the first time that data from a multimessenger GW-EM measurement is used to constrain extra-dimensional models. Thus, our work provides a proof of principle for the possibility of using multimessenger astronomy for probing the geometry of our space-time.

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