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  • 201. Aad, G.
    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 single production of vector-like quarks decaying into Wb in pp collisions at root s=8 TeV with the ATLAS detector2016Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, nr 8, artikkel-id 442Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for singly produced vector-like Q quarks, where Q can be either a T quark with charge +2/3 or a Y quark with charge -4/3, is performed in proton-proton collisions recorded with the ATLAS detector at the LHC. The dataset corresponds to an integrated luminosity of 20.3 fb(-1) and was produced with a centre-of-mass energy of root s = 8 TeV. This analysis targets Q -> Wb decays where the W boson decays leptonically. A veto on massive large-radius jets is used to reject the dominant t (t) over bar background. The reconstructed Q-candidate mass, ranging from 0.4 to 1.2 TeV, is used in the search to discriminate signal from background processes. No significant deviation from the Standard Model expectation is observed, and limits are set on the Q -> Wb cross-section times branching ratio. The results are also interpreted as limits on the QWb coupling and the mixing with the Standard Model sector for a singlet T quark or a Y quark from a doublet. T quarks with masses below 0.95 TeV are excluded at 95 % confidence level, assuming a unit coupling and a BR(T -> Wb) = 0.5, whereas the expected limit is 1.10 TeV.

  • 202. Aad, G.
    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.,
    Test of CP invariance in vector-boson fusion production of the Higgs boson using the Optimal Observable method in the ditau decay channel with the ATLAS detector2016Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, nr 12, artikkel-id 658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A test of CP invariance in Higgs boson production via vector-boson fusion using the method of the Optimal Observable is presented. The analysis exploits the decay mode of the Higgs boson into a pair of τ leptons and is based on 20.3 fb - 1 of proton–proton collision data at s = 8 TeV collected by the ATLAS experiment at the LHC. Contributions from CP-violating interactions between the Higgs boson and electroweak gauge bosons are described in an effective field theory framework, in which the strength of CP violation is governed by a single parameter d~. The mean values and distributions of CP-odd observables agree with the expectation in the Standard Model and show no sign of CP violation. The CP-mixing parameter d~ is constrained to the interval (- 0.11 , 0.05) at 68% confidence level, consistent with the Standard Model expectation of d~ = 0. © 2016, CERN for the benefit of the ATLAS collaboration.

  • 203. Aad, G.
    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.,
    The performance of the jet trigger for the ATLAS detector during 2011 data taking2016Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, nr 10, artikkel-id 526Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction.

  • 204. Aad, G.
    et al.
    Lund-Jensen, Bengt
    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 measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV2013Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 73, nr 3, s. 2304-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of root s = 7 TeV corresponding to an integrated luminosity of 38 pb(-1). Jets are reconstructed with the anti-k(t) algorithm with distance parameters R = 0.4 or R = 0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT >= 20 GeV and pseudorapidities vertical bar eta vertical bar < 4.5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2.5 % in the central calorimeter region (vertical bar eta vertical bar < 0.8) for jets with 60 <= p(T) < 800 GeV, and is maximally 14 % for p(T) < 30 GeV in the most forward region 3.2 <= vertical bar eta vertical bar < 4.5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon p(T), the sum of the transverse momenta of tracks associated to the jet, or a system of low-p(T) jets recoiling against a high-p(T) jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-p(T) jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined.

  • 205. Aad, G.
    et al.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Multi-channel search for squarks and gluinos in √s = 7 TeV pp collisions with the ATLAS detector at the LHC2013Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 73, nr 3, s. 2362-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for supersymmetric particles in final states with zero, one, and two leptons, with and without jets identified as originating from b-quarks, in 4.7 fb(-1) of root s = 7 TeV pp collisions produced by the Large Hadron Collider and recorded by the ATLAS detector is presented. The search uses a set of variables carrying information on the event kinematics transverse and parallel to the beam line that are sensitive to several topologies expected in supersymmetry. Mutually exclusive final states are defined, allowing a combination of all channels to increase the search sensitivity. No deviation from the Standard Model expectation is observed. Upper limits at 95 % confidence level on visible cross-sections for the production of new particles are extracted. Results are interpreted in the context of the constrained minimal supersymmetric extension to the Standard Model and in supersymmetry-inspired models with diverse, high-multiplicity final states.

  • 206. Aad, Georges
    et al.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data2012Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 72, nr 3, s. 1909-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Detailed measurements of the electron performance of the ATLAS detector at the LHC are reported, using decays of the Z, W and J/psi particles. Data collected in 2010 at root s = 7 TeV are used, corresponding to an integrated luminosity of almost 40 pb(-1). The inter-alignment of the inner detector and the electromagnetic calorimeter, the determination of the electron energy scale and resolution, and the performance in terms of response uniformity and linearity are discussed. The electron identification, reconstruction and trigger efficiencies, as well as the charge misidentification probability, are also presented.

  • 207. Aad, Georges
    et al.
    Lafaye, Remi
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Performance of missing transverse momentum reconstruction in proton-proton collisions at root s=7 TeV with ATLAS2012Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 72, nr 1, s. 1844-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The measurement of missing transverse momentum in the ATLAS detector, described in this paper, makes use of the full event reconstruction and a calibration based on reconstructed physics objects. The performance of the missing transverse momentum reconstruction is evaluated using data collected in pp collisions at a centre-of-mass energy of 7 TeV in 2010. Minimum bias events and events with jets of hadrons are used from data samples corresponding to an integrated luminosity of about 0.3 nb(-1) and 600 nb(-1) respectively, together with events containing a Z boson decaying to two leptons (electrons or muons) or a W boson decaying to a lepton (electron or muon) and a neutrino, from a data sample corresponding to an integrated luminosity of about 36 pb(-1). An estimate of the systematic uncertainty on the missing transverse momentum scale is presented.

  • 208. Aad, Georges
    et al.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Performance of the ATLAS Trigger System in 20102012Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 72, nr 1, s. 1849-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proton-proton collisions at root s = 7 TeV and heavy ion collisions at root(NN)-N-s = 2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented.

  • 209. Aad, Georges
    et al.
    Lafaye, Remi
    Cern.
    Lund-Jensen, Bengt
    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 decays of stopped, long-lived particles from 7 TeV pp collisions with the ATLAS detector2012Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 72, nr 4, s. 1965-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New metastable massive particles with electric and colour charge are features of many theories beyond the Standard Model. A search is performed for long-lived gluino-based R-hadrons with the ATLAS detector at the LHC using a data sample corresponding to an integrated luminosity of 31 pb(-1). We search for evidence of particles that have come to rest in the ATLAS detector and decay at some later time during the periods in the LHC bunch structure without proton-proton collisions. No significant deviations from the expected backgrounds are observed, and a cross-section limit is set. It can be interpreted as excluding gluino-based R-hadrons with masses less than 341 GeV at the 95 % C.L., for lifetimes from 10(-5) to 10(3) seconds and a neutralino mass of 100 GeV.

  • 210. Adam, Claire
    et al.
    Kneur, Jean-Loic
    Lafaye, Remi
    Université Savoie, France.
    Plehn, Tilman
    Rauch, Michael
    Zerwas, Dirk
    Measuring Unification2011Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 71, nr 1, s. 1-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If supersymmetry is observed at the LHC its model parameters can be measured at the electroweak scale. We discuss the expected precision on the parameter determination, including a proper treatment of experimental and theoretical errors. Particular attention is paid to degenerate solutions. Using the SFitter framework we perform a bottom-up reconstruction of the unified parameters at the high scale, including a full error propagation.

  • 211. Aguilar-Saavedra, Juan Antonio
    et al.
    Ali, A.
    Allanach, Benjamin C.
    Arnowitt, Richard L.
    Baer, Howard A.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    al., et
    Supersymmetry parameter analysis: SPA convention and project2006Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. C46, s. 43-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e(+)e(-) linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.

  • 212. Biswas, Anirban
    et al.
    Choubey, Sandhya
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik. Harish-Chandra Research Institute, India.
    Khan, Sarif
    Neutrino mass, leptogenesis and FIMP dark matter in a U(1)(B-L) model2017Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 77, nr 12, artikkel-id 875Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U(1)(B-L) gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero U(1)(B-L) charges. All the newly added particles become massive after the breaking of the U(1)(B-L) symmetry by the vacuum expectation value (VEV) of one of the scalar fields phi(H). The other scalar field, phi(DM), which does not have any VEV, becomes automatically stable and can be a viable DM candidate. Neutrino masses are generated using the Type-I seesaw mechanism, while the required lepton asymmetry to reproduce the observed baryon asymmetry can be attained from the CP violating out of equilibrium decays of the RH neutrinos in TeV scale. More importantly within this framework, we study in detail the production of DM via the freeze-in mechanism considering all possible annihilation and decay processes. Finally, we find a situation when DM is dominantly produced from the annihilation of the RH neutrinos, which are at the same time also responsible for neutrino mass generation and leptogenesis.

  • 213.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Clementz, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Herrero-Garcia, J.
    The distribution of inelastic dark matter in the Sun2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 5, artikkel-id 386Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    If dark matter is composed of new particles, these may become captured after scattering with nuclei in the Sun, thermalize through additional scattering, and finally annihilate into neutrinos that can be detected on Earth. If dark matter scatters inelastically into a slightly heavier (O(10-100)keV) state it is unclear whether thermalization occurs. One issue is that up-scattering from the lower mass state may be kinematically forbidden, at which point the thermalization process effectively stops. A larger evaporation rate is also expected due to down-scattering. In this work, we perform a numerical simulation of the capture and thermalization process in order to study the evolution of the dark matter distribution. We then calculate and compare the annihilation rate with that of the often assumed Maxwell–Boltzmann distribution. We also check if equilibrium between capture and annihilation is reached. We find that, unless the mass splitting is very small (≲50keV) and/or the dark matter has a sub-dominant elastic cross section, the dark matter distribution does not reach a stationary state, it is not isothermal, annihilation is severely suppressed, and equilibrium is generally not reached. We also find that evaporation induced by down-scattering is not effective in reducing the total dark matter abundance.

  • 214.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. UAM, CSIC, Inst Fis Teor, Calle Nicolas Cabrera 13-15, Madrid 28049, Spain..
    Clementz, Stefan
    KTH, Skolan för bioteknologi (BIO), Centra, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Herrero-Garcia, Juan
    Univ Adelaide, ARC Ctr Excellence Particle Phys Terascale CoEPP, Adelaide, SA 5005, Australia..
    The distribution of inelastic dark matter in the Sun (vol 78, 386, 2018)2019Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, nr 5, artikkel-id 407Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The annihilation rates in Fig.9 of the original article were incorrectly calculated

  • 215.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain.;Univ Autonoma Madrid, IFT, CSIC, E-28049 Madrid, Spain.
    Fernandez-Martinez, E.
    Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain.;Univ Autonoma Madrid, IFT, CSIC, E-28049 Madrid, Spain..
    Olivares-Del Campo, A.
    Univ Durham, Inst Particle Phys Phenomenol, Dept Phys, South Rd, Durham DH1 3LE, England..
    Pascoli, S.
    Univ Durham, Inst Particle Phys Phenomenol, Dept Phys, South Rd, Durham DH1 3LE, England..
    Rosauro-Alcaraz, S.
    Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain.;Univ Autonoma Madrid, IFT, CSIC, E-28049 Madrid, Spain..
    Titov, A. , V
    Neutrino portals to dark matter2019Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, nr 7, artikkel-id 555Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We explore the possibility that dark matter interactions with Standard Model particles are dominated by interactions with neutrinos. We examine whether it is possible to construct such a scenario in a gauge invariant manner. We first study the coupling of dark matter to the full lepton doublet and confirm that this generally leads to the dark matter phenomenology being dominated by interactions with charged leptons. We then explore two different implementations of the neutrino portal in which neutrinos mix with a Standard Model singlet fermion that interacts directly with dark matter through either a scalar or vector mediator. In the latter cases we find that the neutrino interactions can dominate the dark matter phenomenology. Present neutrino detectors can probe dark matter annihilations into neutrinos and already set the strongest constraints on these realisations. Future experiments such as Hyper-Kamiokande, MEMPHYS, DUNE, or DARWIN could allow to probe dark matter-neutrino cross sections down to the value required to obtain the correct thermal relic abundance.

  • 216.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. UAM CSIC, Inst Fis Teor, Calle Nicolas Cabrera 13-15, Madrid 28049, Spain.
    Fernandez-Martinez, Enrique
    UAM CSIC, Inst Fis Teor, Calle Nicolas Cabrera 13-15, Madrid 28049, Spain.;Univ Auonoma Madrid, Dept Fis Teor, Madrid 28049, Spain..
    Gehrlein, Julia
    UAM CSIC, Inst Fis Teor, Calle Nicolas Cabrera 13-15, Madrid 28049, Spain.;Univ Auonoma Madrid, Dept Fis Teor, Madrid 28049, Spain..
    Hernandez-Garcia, Osu
    INFN, SISSA, Sez Trieste, Via Bonomea 265, I-34136 Trieste, Italy..
    Salvado, Jordi
    Univ Barcelona, Inst Ciencies Cosmos, Diagonal 647, E-08028 Barcelona, Spain..
    IceCube bounds on sterile neutrinos above 10 eV2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 10, artikkel-id 807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the capabilities of IceCube to search for sterile neutrinos with masses above 10 eV by analyzing its nu(mu) disappearance atmospheric neutrino sample. We find that IceCube is not only sensitive to the mixing of sterile neutrinos to muon neutrinos, but also to the more elusive mixing with tau neutrinos through matter effects. The currently released 1-year data shows a mild preference, between 0.75 and 3 sigma depending on the binning and flux adopted, for non-zero sterile mixing. This hint overlaps with the favored region for the sterile neutrino interpretation of the ANITA upward shower although the null results from CHORUS and NOMAD on nu(mu) to nu(tau) oscillations in vacuum exclude this interpretation, while through a different channel and using a different energy range. At the 99% C.L. an upper bound is obtained that improves over the present Super-Kamiokande and DeepCore constraints in some parts of the parameter space. We also investigate the physics reach of the roughly 8 years of data that is already on tape as well as a forecast of 20 years data to probe the present hint or improve upon current constraints.

  • 217.
    Blennow, Mattias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Meloni, Davide
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Terranova, Francesco
    Westerberg, Mattias
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    Non-standard interactions using the OPERA experiment2008Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 56, nr 4, s. 529-536Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the implications of non-standard interactions on neutrino oscillations in the OPERA experiment. In particular, we study the non-standard interaction parameter epsilon(mu tau) . We show that the OPERA experiment has a unique opportunity to reduce the allowed region for this parameter compared with other experiments such as the MINOS experiment, mostly due to the higher neutrino energies in the CNGS beam compared to the NuMI beam. We find that OPERA is mainly sensitive to a combination of standard and non-standard parameters and that a resulting anti-resonance effect could suppress the expected number of events. Furthermore, we show that running OPERA for five years each with neutrinos and anti-neutrinos would help in resolving the degeneracy between the standard parameters and epsilon(mu tau) . This scenario is significantly better than the scenario with a simple doubling of the statistics by running with neutrinos for ten years.

  • 218.
    Choubey, Sandhya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. HBNI.
    Dutta, Debajyoti
    HBNI, Harish Chandra Res Inst, Chhatnag Rd, Allahabad 211019, Uttar Pradesh, India..
    Pramanik, Dipyaman
    HBNI, Harish Chandra Res Inst, Chhatnag Rd, Allahabad 211019, Uttar Pradesh, India..
    Measuring the sterile neutrino CP phase at DUNE and T2HK2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 4, artikkel-id 339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The CP phases associated with the sterile neutrino cannot be measured in the dedicated short-baseline experiments being built to test the sterile neutrino hypothesis. On the other hand, these phases can be measured in long-baseline experiments, even though the main goal of these experiments is not to test or measure sterile neutrino parameters. In particular, the sterile neutrino phase delta(24) affects the charged-current electron appearance data in long-baseline experiment. In this paper we show how well the sterile neutrino phase delta(24) can be measured by the next-generation long-baseline experiments DUNE, T2HK (and T2HKK). We also show the expected precision with which this sterile phase can be measured by combining the DUNE data with data from T2HK or T2HKK. The T2HK experiment is seen to be able to measure the sterile phase delta(24) to a reasonable precision. We also present the sensitivity of these experiments to the sterile mixing angles, both by themselves, as well as when DUNE is combined with T2HK or T2HKK.

  • 219.
    Choubey, Sandhya
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik. Harish-Chandra Research Institute Allahabad India; Homi Bhabha National Institute Mumbai India.
    Khan, S.
    Mitra, M.
    Mondal, S.
    Singlet-triplet fermionic dark matter and LHC phenomenology2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 4, artikkel-id 302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is well known that for the pure standard model triplet fermionic WIMP-type dark matter (DM), the relic density is satisfied around 2 TeV. For such a heavy mass particle, the production cross-section at 13 TeV run of LHC will be very small. Extending the model further with a singlet fermion and a triplet scalar, DM relic density can be satisfied for even much lower masses. The lower mass DM can be copiously produced at LHC and hence the model can be tested at collider. For the present model we have studied the multi jet (≥2j) + missing energy ([InlineEquation not available: see fulltext.]) signal and show that this can be detected in the near future of the LHC 13 TeV run. We also predict that the present model is testable by the earth based DM direct detection experiments like Xenon-1T and in future by Darwin. 

  • 220.
    Conroy, Aindriu
    et al.
    Univ Lancaster, Phys Dept, Lancaster LA1 4YB, England..
    Koivisto, Tomi S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    The spectrum of symmetric teleparallel gravity2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 11, artikkel-id 923Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    General Relativity and its higher derivative extensions have symmetric teleparallel reformulations in terms of the non-metricity tensor within a torsion-free and flat geometry. These notes present a derivation of the exact propagator for the most general infinite-derivative, even-parity and generally covariant theory in the symmetric teleparallel spacetime. The action made up of the non-metricity tensor and its contractions is decomposed into terms involving the metric and a gauge vector field and is found to complement the previously known non-local ghost- and singularity-free theories.

  • 221.
    Dialektopoulos, Konstantinos F.
    et al.
    Yangzhou Univ, Coll Phys Sci & Technol, Ctr Gravitat & Cosmol, Yangzhou 225009, Jiangsu, Peoples R China. ialektopoulos, Konstantinos F..
    Koivisto, Tomi S.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Capozziello, Salvatore
    Noether symmetries in symmetric teleparallel cosmology2019Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, nr 7, artikkel-id 606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a general theory of all possible quadratic, first-order derivative terms of the non-metricity tensor in the framework of Symmetric Teleparallel Geometry. We apply the Noether Symmetry Approach to classify those models that are invariant under point transformations in a cosmological background and we use the symmetries of these models to reduce the dynamics of the system in order to find analytical solutions.

  • 222. Ghosh, M.
    et al.
    Goswami, S.
    Raut, Sushant K.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik. Physical Research Laboratory, Navrangpura, Ahmedabad, India.
    Maximizing the DUNE early physics output with current experiments2016Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, nr 3, artikkel-id 114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deep underground neutrino experiment (DUNE) is a proposed next generation superbeam experiment at Fermilab. Its aims include measuring the unknown neutrino oscillation parameters—the neutrino mass hierarchy, the octant of the mixing angle θ23, and the CP-violating phase δCP. The current and upcoming experiments T2K, NOνA, and ICAL@INO will also be collecting data for the same measurements. In this paper, we explore the sensitivity reach of DUNE in combination with these other experiments. We evaluate the least exposure required by DUNE to determine the above three unknown parameters with reasonable confidence. We find that for each case, the inclusion of data from T2K, NOνA, and ICAL@INO help to achieve the same sensitivity with a reduced exposure from DUNE thereby helping to economize the configuration. Further, we quantify the effect of the proposed near detector on systematic errors and study the consequent improvement in sensitivity. We also examine the role played by the second oscillation cycle in furthering the physics reach of DUNE. Finally, we present an optimization study of the neutrino–antineutrino running of DUNE.

  • 223. Kuhnel, Florian
    et al.
    Rampf, Cornelius
    Sandstad, Marit
    Effects of critical collapse on primordial black-hole mass spectra2016Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 76, nr 2, artikkel-id 93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain inflationary models as well as realisations of phase transitions in the early Universe predict the formation of primordial black holes. For most mass ranges, the fraction of matter in the form of primordial black holes is limited by many different observations on various scales. Primordial black holes are assumed to be formed when overdensities that cross the horizon have Schwarzschild radii larger than the horizon. Traditionally it was therefore assumed that primordial black-holemasses were equal to the horizon mass at their time of formation. However, detailed calculations of their collapse show that primordial black holes formed at each point in time should rather form a spectrum of different masses, obeying critical scaling. Though this has been known for more than 15 years, the effect of this scaling behaviour is largely ignored when considering predictions for primordial black-hole mass spectra. In this paper we consider the critical collapse scaling for a variety of models which produce primordial black holes, and find that it generally leads to a shift, broadening and an overall decrease of the mass contained in primordial black holes. This effect is model and parameter dependent and cannot be contained by a constant rescaling of the spectrum; it can become important and should be taken into account when comparing to observational constraints.

  • 224.
    Kühnel, Florian
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Alballova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, S-10691 Stockholm, Sweden..
    Ohlsson, Tommy
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Alballova Univ Ctr, Oskar Klein Ctr Cosmoparticle Phys, Roslagstullsbacken 21, S-10691 Stockholm, Sweden.;Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Decaying dark matter in halos of primordial black holes2019Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, nr 8, artikkel-id 687Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate photon signatures of general decaying dark-matter particles in halos of primordial black holes. We derive the halo-profile density and the total decay rate for these combined dark-matter scenarios. For the case of axion-like particles of masses below O(1)keV, we find strong bounds on the decay constant which are several orders of magnitude stronger than the strongest existing bounds, for all halo masses above O(10-5) solar masses. Using future X-ray measurements, it will be possible to push these bounds on such combined dark-matter scenarios even further.

  • 225.
    Lafaye, Remi
    et al.
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Plehn, Tilman
    Rauch, Michael
    Zerwas, Dirk
    Measuring Supersymmetry2008Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 54, nr 4, s. 617-644Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    If new physics is found at the LHC (and the ILC) the reconstruction of the underlying theory should not be biased by assumptions about high-scale models. For the mapping of many measurements onto high-dimensional parameter spaces we introduce SFitter with its new weighted Markov chain technique. SFitter constructs an exclusive likelihood map, determines the best-fitting parameter point and produces a ranked list of the most likely parameter points. Using the example of the TeV-scale supersymmetric Lagrangian we show how a high-dimensional likelihood map will generally include degeneracies and strong correlations. SFitter allows us to study such model-parameter spaces employing Bayesian as well as frequentist constructions. We illustrate in detail how it should be possible to analyze high-dimensional new-physics parameter spaces like the TeV-scale MSSM at the LHC. A combination of LHC and ILC measurements might well be able to completely cover highly complex TeV-scale parameter spaces.

  • 226. Meier, Christoph
    et al.
    Ohlsson, Tommy
    KTH, Tidigare Institutioner, Fysik.
    Analysis of a three flavor neutrino oscillation fit to recent Super-Kamiokande data2000Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 18, nr 1, s. 97-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have analyzed the most recent available Super-Kamiokande data in a three flavor neutrino oscillation model. We have here neglected possible matter effects and we performed a fit to atmospheric and solar Super-Kamiokande data. We have investigated a large parameter range where the mixing angles were restricted to 0 less than or equal to theta (i) less than or equal to pi /2, i = 1,2,3, and the mass squared differences were taken to be in the intervals 10(-11) eV(2) less than or equal to Deltam(2) less than or equal to 10(-2) eV(2) and 10(-4) eV(2) less than or equal to DeltaM(2) less than or equal to 10 eV(2), i.e., the hierarchy between the mass squared differences is not completely determined. This yielded a best solution characterized by the parameter values theta (1) similar or equal to 45 degrees, theta (2) similar or equal to 10 degrees, theta (3) similar or equal to 45 degrees, Deltam(2) similar or equal to 4.4 x 10(-10) eV(2), and DeltaM(2) similar or equal to 1.01. x 10(-3) eV(2), which shows that the analyzed experimental data speak in favor of a bimaximal mixing scenario with one of the mass squared differences in the just-so domain and the other one in the range capable of providing a solution to the atmospheric neutrino problem.

  • 227. Myrzakulov, R.
    et al.
    Sebastiani, L.
    Vagnozzi, Sunny
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen Ø, Denmark.
    Inflation in f (R, phi)-theories and mimetic gravity scenario2015Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 75, nr 9, artikkel-id 444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate inflation within f (R, phi)-theories, where a dynamical scalar field is coupled to gravity. A class of models which can support early-time acceleration with the emerging of an effective cosmological constant at high curvature is studied. The dynamics of the field allow for exit from inflation leading to the correct amount of inflation in agreement with cosmological data. Furthermore, the spectral index and tensor-to-scalar ratio of the models are carefully analyzed. A generalization of the theory to incorporate dark matter in the context of mimetic gravity, and further extensions of the latter, are also discussed.

  • 228.
    Ohlsson, Tommy
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Snellman, Håkan
    KTH, Tidigare Institutioner, Fysik.
    Chiral quark model analysis of nucleon quark sea isospin asymmetry and spin polarization1999Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 7, nr 3, s. 501-506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We analyze recent measurements of the nucleon quark sea isospin asymmetry in terms of the chiral quark model. The new measurements indicate that the SU(3) model with modest symmetry breaking and no eta' Goldstone boson gives a satisfactory description of data. We also discuss the matching parameter for the axial-vector current. Finally, we analyze the nucleon quark spin polarization measurements directly in the chiral quark model without using any SU(3) symmetry assumption on the hyperon axial-vector form factors. The new data indicate that the chiral quark model gives a remarkably good and consistent description of all low energy baryon measurements.

  • 229.
    Ohlsson, Tommy
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Snellman, Håkan
    KTH, Tidigare Institutioner, Fysik.
    Neutrino oscillations with three flavors in matter of varying density2001Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 20, nr 3, s. 507-515Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we discuss the evolution operator and the transition probabilities expressed as functions of the vacuum mass squared differences, the vacuum mixing angles, and the matter density parameter for three flavor neutrino oscillations in matter of varying density in the plane wave approximation. The applications of this to neutrino oscillations in a model of the earth's matter density profile, step function matter density profiles, constant matter density profiles. linear matter density profiles, and finally in a model of the sun's matter density profile are discussed. We show that for matter density profiles which do not fluctuate too much, the total evolution operator consisting of n operators can be replaced by one single evolution operator in the semi-classical approximation.

  • 230.
    Ohlsson, Tommy
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Snellman, Håkan
    KTH, Tidigare Institutioner, Fysik.
    Weak form factors for semileptonic octet baryon decays in the chiral quark model1999Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 6, nr 2, s. 285-296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the weak vector and axial-vector form factors of first- and second-class currents for the semileptonic octet baryon decays in the spirit of the chiral quark model. Our results for the weak magnetism form factors are consistent with the conserved vector current (CVC) results. The induced pseudotensor form factors, which are highly model dependent. are small. The overall performance of the chiral quark model is quite good and in general agreement with existing experimental data.

  • 231.
    Ohlsson, Tommy
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Snellman, Håkan
    KTH, Tidigare Institutioner, Fysik.
    Weak magnetism in chiral quark models2000Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 12, nr 2, s. 271-276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We discuss symmetry breaking in the weak magnetism form factors for the semileptonic octet baryon decays. In the chiral quark model, the symmetry breaking can be accounted for in the masses and the quark spin polarizations can take on more general values due to Goldstone boson depolarization. Here we clarify some features of the chiral quark model prediction for the weak magnetism and compare to the corresponding result of the chiral quark soliton model.

  • 232.
    Yao, Yuan
    et al.
    Yangzhou Univ, Coll Phys Sci & Technol, Ctr Gravitat & Cosmol, 180 Siwangting Rd, Yangzhou 225002, Jiangsu, Peoples R China..
    Hou, Meng-Shi
    Yangzhou Univ, Coll Phys Sci & Technol, Ctr Gravitat & Cosmol, 180 Siwangting Rd, Yangzhou 225002, Jiangsu, Peoples R China..
    Ong, Yen Chin
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Yangzhou Univ, Coll Phys Sci & Technol, Ctr Gravitat & Cosmol, 180 Siwangting Rd, Yangzhou 225002, Jiangsu, Peoples R China.;Shanghai Jiao Tong Univ, Sch Aeronaut & Astronaut, Shanghai 200240, Peoples R China. ; Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden..
    A complementary third law for black hole thermodynamics2019Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, nr 6, artikkel-id 513Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are some examples in the literature, in which despite the fact that the underlying theory or model does not impose a lower bound on the size of black holes, the final temperature under Hawking evaporation is nevertheless finite and nonzero. We show that under some loose conditions, the black hole is necessarily an effective remnant, in the sense that its evaporation time is infinite. That is, the final state that there is nonzero finite temperature despite having no black hole remaining cannot be realized. We discuss the limitations, subtleties, and the implications of this result, which is reminiscent of the third law of black hole thermodynamics, but with the roles of temperature and size interchanged. We therefore refer to our result as the complementary third law for black hole thermodynamics.

  • 233.
    Zheltukhin, Aleksandr
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Kharkov Institute of Physics and Technology, Ukraine .
    Branes as solutions of gauge theories in gravitational field2014Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 74, nr 9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The idea of the Gauss map is unified with the concept of branes as hypersurfaces embedded into D-dimensional Minkowski space. The map introduces new generalized coordinates of branes alternative to their world vectors x and identified with the gauge and other massless fields. In these coordinates the Dirac p-branes realize extremals of the Euler–Lagrange equations of motion of a (p+1)-dimensional SO(D-p-1) gauge-invariant action in a gravitational background.

2345 201 - 233 of 233
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