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• 1. Aaboud, M.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
High-E-T isolated-photon plus jets production in pp collisions at root s=8 TeV with the ATLAS detector2017In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 918, p. 257-316Article in journal (Refereed)

The dynamics of isolated-photon plus one-, two- and three-jet production in pp collisions at a centre-of-mass energy of 8 TeV are studied with the ATLAS detector at the LHC using a data set with an integrated luminosity of 20.2 fb(-1). Measurements of isolated-photon plus jets cross sections are presented as functions of the photon and jet transverse momenta. The cross sections as functions of the azimuthal angle between the photon and the jets, the azimuthal angle between the jets, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system are presented. The pattern of QCD radiation around the photon and the leading jet is investigated by measuring jet production in an annular region centred on each object; enhancements are observed around the leading jet with respect to the photon in the directions towards the beams. The experimental measurements are compared to several different theoretical calculations, and overall a good description of the data is found. (C) 2017 The Author(s). Published by Elsevier B.V.

• 2. Aad, G.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. University of Chicago. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
Measurement of the differential cross-sections of inclusive, prompt and non-prompt J/psi production in proton-proton collisions at root s=7 TeV2011In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 850, no 3, p. 387-444Article in journal (Refereed)

The inclusive J/psi production cross-section and fraction of J/psi mesons produced in B-hadron decays are measured in proton proton collisions at root s = 7 TeV with the ATLAS detector at the LHC, as a function of the transverse momentum and rapidity of the J/psi, using 2.3 pb(-1) of integrated luminosity. The cross-section is measured from a minimum P(T) of 1 GeV to a maximum of 70 GeV and for rapidities within vertical bar y vertical bar < 2.4 giving the widest reach of any measurement of J/psi production to date. The differential production cross-sections of prompt and non-prompt J/psi are separately determined and are compared to Colour Singlet NNLO*, Colour Evaporation Model, and FONLL predictions.

• 3. Aad, G.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
Measurement of the total cross section from elastic scattering in pp collisions at root s=7 TeV with the ATLAS detector2014In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 889, p. 486-548Article in journal (Refereed)

A measurement of the total pp cross section at the LHC at root s = 7 TeV is presented. In a special run with high-beta* beam optics, an integrated luminosity of 80 mu b(-1) was accumulated in order to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable t. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the vertical bar t vertical bar range from 0.01 GeV2 to 0.1 GeV2 to extrapolate to vertical bar t vertical bar --> 0, the total cross section, sigma(tot)(pp --> X), is measured via the optical theorem to be: sigma(tot)(pp --> X) = 95.35 +/- 0.38 (stat.) +/- 1.25 (exp.) +/- 0.37 (extr.) mb, where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation to vertical bar t vertical bar --> 0. In addition, the slope of the elastic cross section at small vertical bar t vertical bar is determined to be B = 19.73 +/- 0.14 (stat.) +/- 0.26 (syst.) GeV-2.

• 4. Aad, G.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
Dynamics of isolated-photon plus jet production in pp collisions at root s=7 TeV with the ATLAS detector2013In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 875, no 3, p. 483-535Article in journal (Refereed)

The dynamics of isolated-photon plus jet production in pp collisions at a centre-of-mass energy of 7 TeV has been studied with the ATLAS detector at the LHC using an integrated luminosity of 37 pb(-1). Measurements of isolated-photon plus jet bin-averaged cross sections are presented as functions of photon transverse energy, jet transverse momentum and jet rapidity. In addition, the bin-averaged cross sections as functions of the difference between the azimuthal angles of the photon and the jet, the photon jet invariant mass and the scattering angle in the photon jet centre-of-mass frame have been measured. Next-to-leading-order QCD calculations are compared to the measurements and provide a good description of the data, except for the case of the azimuthal opening angle.

• 5. Aad, G.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
Measurement of the b-hadron production cross section using decays to D*(+)mu X- final states in pp collisions at root s=7 TeV with the ATLAS detector2012In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 864, no 3, p. 341-381Article in journal (Refereed)

The b-hadron production cross section is measured with the ATLAS detector in pp collisions at root s = 7 TeV, using 3.3 pb(-1) of integrated luminosity, collected during the 2010 LHC run. The b-hadrons are selected by partially reconstructing D*(+)mu X- final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a b-hadron with p(T) > 9 GeV and vertical bar eta vertical bar < 2.5 is 32.7 +/- 0.8(stat.)(-6.8)(+4.5)(syst.) mu b, higher than the next-to-leading-order QCD predictions but consistent within the experimental and theoretical uncertainties.

• 6. Aad, G.
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
Measurement of D-*+/-, D-+/- and D-S(+/-) meson production cross sections in pp collisions at root s=7 TeV with the ATLAS detector2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 907, p. 717-763Article in journal (Refereed)

The production of D*(+/-), D-+/- and D-S(+/-) charmed mesons has been measured with the ATLAS detector in pp collisions at,/7s = 7 TeV at the LHC, using data corresponding to an integrated luminosity of 280 nb(-)1(.) The charmed mesons have been reconstructed in the range of transverse momentum 3.5 < p(T)(D) < 100 GeV and pseudorapidity vertical bar eta(D)vertical bar < 2.1. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for D*(+/-) and D-+/- production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible D cross sections and an extrapolation to the full kinematic phase space, the strangeness -suppression factor in charm fragmentation, the fraction of charged non -strange D mesons produced in a vector state, and the total cross section of charm production at root s = 7 TeV were derived.

• 7. Akhmedov, Evgeny
KTH, Superseded Departments, Physics.
T violation in neutrino oscillations in matter2001In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 608, no 02-jan, p. 394-422Article in journal (Refereed)

We consider the interplay of fundamental and matter-induced T violation effects in neutrino oscillations in matter. After discussing the general features of these effects we derive a simple approximate analytic expression for the T-violating probability asymmetry DeltaP(ab)(T) for three-flavour neutrino oscillations in a matter with an arbitrary density profile in terms of the two-flavour neutrino amplitudes. Explicit examples are given for the cases of a two-layer medium and for the adiabatic Emit in the general case. We then discuss implications of the obtained results for long baseline experiments. We show, in particular, that asymmetric matter effects cannot hinder the determination of the fundamental CP- and T-violating phase delta (CP) in the long baseline experiments as far as the error in this determination is larger than 1% at 99% CL. Since there are no T-violating effects in the two-flavour case, and in the limits of vanishing theta (13) or Deltam(21)(2) the three-flavour neutrino oscillations effectively reduce to the two-flavour ones, studying the T-violating asymmetries ApT ab can in principle provide us with a complementary means of measuring theta (13) and Deltam(21)(2).

• 8.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
Dublin Inst Adv Studies, Sch Theoret Phys, 10 Burlington Rd, Dublin 4, Ireland.. Imperial Coll London, Blackett Lab, Theoret Phys, London SW7 2AZ, England.;Univ Oxford, Math Inst, Andrew Wiles Bldg,Woodstock Rd, Oxford OX2 6GG, England.. Ctr Studi & Ric Enrico Fermi, Via Panisperna 89A, I-00184 Rome, Italy.;Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy.;INFN, Sez Padova, Via Marzolo 8, I-35131 Padua, Italy.. Ctr Astron & Particle Theory, Univ Pk, Nottingham NG7 2RD, England.;Univ Lisbon, Inst Super Tecn, Dept Math, Ctr Math Anal Geometry & Dynam Syst, Av Rovisco Pais, P-1049001 Lisbon, Portugal.. Imperial Coll London, Blackett Lab, Theoret Phys, London SW7 2AZ, England..
Are all supergravity theories Yang-Mills squared?2018In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 934, p. 606-633Article in journal (Refereed)

Using simple symmetry arguments we classify the ungauged D = 4, N = 2 supergravity theories, coupled to both vector and hyper multiplets through homogeneous scalar manifolds, that can be built as the product of N = 2 and N= 0 matter-coupled Yang-Mills gauge theories. This includes all such supergravities with two isolated exceptions: pure supergravity and the T-3 model.

• 9. Antusch, Stefan
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
Perturbative estimates of lepton mixing angles in unified models2009In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 820, no 1-2, p. 32-46Article in journal (Refereed)

Many unified models predict two large neutrino mixing angles, with the charged lepton mixing angles being small and quark-like, and the neutrino masses being hierarchical. Assuming this, we present simple approximate analytic formulae giving the lepton mixing angles in terms of the underlying high energy neutrino mixing angles together with small perturbations due to both charged lepton corrections and renormalisation group (RG) effects, including also the effects of third family canonical normalization (CN). We apply the perturbative formulae to the ubiquitous case of tri-bimaximal neutrino mixing at the unification scale, in order to predict the theoretical corrections to mixing angle predictions and sum rule relations, and give a general discussion of all limiting cases. We also discuss the implications for the sum rule relations of the measurement of a non-zero reactor angle, as hinted at by recent experimental measurements.

• 10. Babaev, Egor
Phase diagram of planar U(l) x U(l) superconductor - Condensation of vortices with fractional flux and a superfluid state2004In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 686, no 3, p. 397-412Article in journal (Refereed)

We discuss a phase diagram of two-dimensional U(1) x U(l) superconductor in the field theoretic formalizm of [Phys. Rev. Lett. 89 (2002) 067001]. In particular we discuss that when penetration length is short the system exhibit a quasi-neutral quasi-superfluid state which is a state when quasi-long range order sets in only in phase difference while individually the phases are disordered.

• 11.
Physik-Department, Technische Universität München.
KTH, School of Engineering Sciences (SCI), Theoretical Physics. Department of Physics, Oklahoma State University.
Discretized gravity in 6D warped space2007In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 278, no 1-3, p. 32-63Article in journal (Refereed)

We consider discretized gravity in six dimensions. where the two extra dimensions have been compactified on a hyperbolic disk of constant curvature. We analyze different realizations of lattice gravity on the disk at the level of an effective field theory for massive gravitons. It is shown that the observed strong coupling scale of lattice gravity in discretized five-dimensional flat or warped space can be increased if the latticized fifth dimension is wrapped around a hyperbolic disk that has a non-trivial warp factor. As an application, we also study the generation of naturally small Dirac neutrino masses via a discrete volume suppression mechanism and discuss briefly collider implications of our model.

• 12. Baussan, E.
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics. KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
A very intense neutrino super beam experiment for leptonic CP violation discovery based on the European spallation source linac2014In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 885, p. 127-149Article in journal (Refereed)

Very intense neutrino beams and large neutrino detectors will be needed in order to enable the discovery of CP violation in the leptonic sector. We propose to use the proton linac of the European Spoliation Source currently under construction in Lund, Sweden, to deliver, in parallel with the spoliation neutron production, a very intense, cost effective and high performance neutrino beam. The baseline program for the European Spoliation Source linac is that it will be fully operational at 5 MW average power by 2022, producing 2 GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron production and 14 pulses/s for neutrino production. Furthermore, because of the high current required in the pulsed neutrino horn, the length of the pulses used for neutrino production needs to be compressed to a few mu s with the aid of an accumulator ring. A long baseline experiment using this Super Beam and a megaton underground Water Cherenkov detector located in existing mines 300-600 km from Lund will make it possible to discover leptonic CP violation at 5 sigma significance level in up to 50% of the leptonic Dirac CP-violating phase range. This experiment could also determine the neutrino mass hierarchy at a significance level of more than 3 sigma if this issue will not already have been settled by other experiments by then. The mass hierarchy performance could be increased by combining the neutrino beam results with those obtained from atmospheric neutrinos detected by the same large volume detector. This detector will also be used to measure the proton lifetime, detect cosmological neutrinos and neutrinos from supernova explosions. Results on the sensitivity to leptonic CP violation and the neutrino mass hierarchy are presented.

• 13. Blaksley, Carl
Heavy neutrinos and lepton number violation in ℓp colliders2011In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 852, no 2, p. 353-365Article in journal (Refereed)

We discuss the prospects of studying lepton number violating processes in order to identify Majorana neutrinos from low scale seesaw mechanisms at lepton-proton colliders. In particular, we consider the scenarios of colliding electrons with LHC energy protons and, motivated by the efforts towards the construction of a muon collider, the prospects of muon-proton collisions. We find that present constraints on the mixing of the Majorana neutrinos still allow for a detectable signal at these kind of facilities given the smallness of the Standard Model background. We discuss possible cuts in order to further increase the signal over background ratio and the prospects of reconstructing the neutrino mass from the kinematics of the final state particles.

• 14.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
q-Poincaré supersymmetry in AdS5/CFT42018In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 928, p. 321-355Article in journal (Refereed)

We consider the exact S-matrix governing the planar spectral problem for strings on AdS5×S5 and N=4 super Yang–Mills, and we show that it is invariant under a novel “boost” symmetry, which acts as a differentiation with respect to the particle momentum. This generator leads us also to reinterpret the usual centrally extended psu(2|2) symmetry, and to conclude that the S-matrix is invariant under a q-Poincaré supersymmetry algebra, where the deformation parameter is related to the ‘t Hooft coupling. We determine the two-particle action (coproduct) that turns out to be non-local, and study the property of the new symmetry under crossing transformations. We look at both the strong-coupling (large tension in the string theory) and weak-coupling (spin-chain description of the gauge theory) limits; in the former regime we calculate the cobracket utilising the universal classical r-matrix of Beisert and Spill. In the eventuality that the boost has higher partners, we also construct a quantum affine version of 2D Poincaré symmetry, by contraction of the quantum affine algebra Uq(sl2ˆ) in Drinfeld's second realisation.

• 15.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. DESY Hamburg, Germany.
Spectra of sigma models on semi-symmetric spaces2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 906, p. 342-366Article in journal (Refereed)

Sigma models on semi-symmetric spaces provide the central building block for string theories on AdS backgrounds. Under certain conditions on the global supersymmetry group they can be made one-loop conformal by adding an appropriate fermionic Wess-Zumino term. We determine the full one-loop dilation operator of the theory. It involves an interesting new XXZ-like interaction term. Eigenvalues of our dilation operator, i.e. the one-loop anomalous dimensions, are computed for a few examples.

• 16.
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
Atmospheric neutrinos: Status and prospects2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562Article in journal (Refereed)

We present an overview of the current status of neutrino oscillation studies at atmospheric neutrino experiments. While the current data gives some tantalising hints regarding the neutrino mass hierarchy, octant of θ23 and δCP, the hints are not statistically significant. We summarise the sensitivity to these sub-dominant three-generation effects from the next-generation proposed atmospheric neutrino experiments. We next present the prospects of new physics searches such as non-standard interactions, sterile neutrinos and CPT violation studies at these experiments.

• 17. Di Iura, A.
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
Phenomenology of SU(5) low-energy realizations: The diphoton excess and Higgs flavor violation2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 911, p. 388-424Article in journal (Refereed)

We discuss different SU(5) low-energy realizations and illustrate their use with the diphoton excess and Higgs flavor violation, which require new physics at the TeV scale. In particular, we study two scenarios for a 750 GeV resonance: in the first one the resonance belongs to the adjoint of SU(5), being either an SU(2)L singlet or a triplet, while in the second case the signal is due to the CP-even and CP-odd states of a new SU(2)L Higgs doublet belonging to a 45H or a 70H representations, giving rise to a two-Higgs doublet model at low energies. We study the fine-tuning needed for the desired members of the multiplets to be light enough, while having the rest at the GUT scale. In these scenarios, the production and decay into photons of the new resonance are mediated by the leptoquarks (LQ) present in these large SU(5) representations. We analyze the phenomenology of such scenarios, focusing on the most relevant predictions that can help to disentangle the different models, like decays into gauge bosons, Standard Model (SM) fermions and LQs pair production. In the case of the 45H (the Georgi–Jarlskog model), we also study the possibility to have Higgs flavor violation. We find that Bs mixing limits (in addition to τ→μγ) always imply that Br(h→τμ,bs)≲10−5.

• 18. Frohlich J,
KTH, Superseded Departments, Mathematics.
Asymptotic form of zero energy wave functions in supersymmetric matrix models2000In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 567, no 1-2, p. 231-248Article in journal (Refereed)

We derive the power law decay, and asymptotic form, of SU(2) X Spin(d) invariant wavefunctions satisfying Q(beta)psi=0 for all s(d) = 2(d - 1) supercharges of reduced (d + 1)-dimensional supersymmetric SU(2) Yang-Mills theory, of, respectively, the SU(2) matrix model related to supermembranes in d + 2 dimensions.

• 19. Grosse, H.
KTH, Superseded Departments, Physics.
Chiral Schwinger models without gauge anomalies2000In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 587, no 03-jan, p. 568-584Article in journal (Refereed)

We find a large class of quantum gauge models with massless fermions where the coupling to the gauge fields is not chirally symmetric and which nevertheless do not suffer from gauge anomalies. To be specific we study two dimensional Abelian models in the Hamiltonian framework which can be constructed and solved by standard techniques. The general model describes Np photon fields and NF flavors of Dirac fermions with 2N(F)N(P) different coupling constants, i.e., the chiral component of each fermion can he coupled to the gauge fields differently We construct these models and find conditions so that no gauge anomaly appears. If these conditions hold it is possible to construct and solve the model explicitly, so that gauge- and Lorentz invariance are manifest.

• 20. Hernandez, Andres
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
Effective action in a general chiral model: Next to leading order derivative expansion in the worldline method2008In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 793, no 3, p. 425-450Article in journal (Refereed)

We present a formalism to determine the imaginary part of a general chiral model in the derivative expansion. Our formalism is based on the worldline path integral for the covariant current that can be given in an explicit chiral and gauge covariant form. The effective action is then obtained by integrating the covariant current, taking account of the anomaly.

• 21.
KTH, Superseded Departments, Mathematics.
Dimensionally reduced SYM4 as solvable matrix quantum mechanics2000In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 571, no 1-2, p. 479-509Article in journal (Refereed)

We study the quantum mechanical model obtained as a dimensional reduction of N = 1 super Yang-Mills theory to a periodic light cone "time''. After mapping the theory to a cohomological field theory, the partition function (with periodic boundary conditions) regularized by a massive term appears to be equal to the partition function of the twisted matrix oscillator. We show that this partition function perturbed by the operator of the holonomy around the time circle is a tau function of Toda hierarchy. We solve the model in the large N limit and study the universal properties of the solution in the scaling limit of vanishing perturbation. We find in this limit a phase transition of Gross-Witten type.

• 22.
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.). KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
Construction of the zero-energy state of SU(2)-matrix theory: Near the origin2009In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 817, no 3, p. 155-166Article in journal (Refereed)

We explicitly construct a (unique) Spin(9) x SU(2) singlet state, phi, involving only the fermionic degrees of freedom of the supersymmetric matrix-model corresponding to reduced 10-dimensional super-Yang Mills theory, respectively supermembranes in 11-dimensional Minkowski space. Any non-singular wave-function annihilated by the 16 supercharges of SU(2) matrix theory must, at the origin (where it is assumed to be non-vanishing) reduce to phi.

• 23.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
Lorentz-invariant membranes and finite matrix approximations2011In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 849, no 3, p. 628-635Article in journal (Refereed)

The question of Lorentz invariance for finite N approximations of relativistic membranes is addressed. We find that one of the classical manifestations of Lorentz invariance is no! possible for N x N matrices (at least when N = 2 or 3). How the symmetry is restored in the large N limit is studied numerically.

• 24. Huber, Stephan J.
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
Electroweak phase transition and baryogenesis in the nMSSM2006In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 757, no 1-2, p. 172-196Article in journal (Refereed)

We analyze the nMSSM with CP violation in the singlet sector. We study the static and dynamical properties of the electroweak phase transition. We conclude that electroweak baryogenesis in this model is generic in the sense that if the present limits on the mass spectrum are applied, no severe additional tuning is required to obtain a strong first-order phase transition and to generate a sufficient baryon asymmetry. For this we determine the shape of the nucleating bubbles, including the profiles of CP-violating phases. The baryon asymmetry is calculated using the advanced transport theory to first and second order in gradient expansion presented recently. Still, first and second generation sfermions must be heavy to avoid large electric dipole moments.

• 25.
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
Optimized Fock space in the large $N$ limit of quartic interactions in Matrix Models2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 906, p. 497-523Article in journal (Refereed)

We consider the problem of quantization of the bosonic membrane via the large N limit of its matrix regularizations HN in Fock space. We prove that there exists a choice of the Fock space frequency such that HN can be written as a sum of a non-interacting Hamiltonian H0,N and the original normal ordered quartic potential. Using this decomposition we obtain upper and lower bounds for the ground state energy in the planar limit, we study a perturbative expansion about the spectrum of H0,N , and show that the spectral gap remains finite at N=∞ at least up to the second order. We also apply the method to the U(N) -invariant anharmonic oscillator, and demonstrate that our bounds agree with the exact result of Brezin et al.

• 26.
Institute of Physics, Jagiellonian University, Poland.
Uniqueness of the coordinate independent Spin(9)xSU(2) state of Matrix Theory2010In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 838, no 3, p. 413-421Article in journal (Refereed)

We explicitly prove, using some nontrivial identities involving gamma matrices, that there can be only one Spin(9) x SU(2) invariant state which depends only on fermionic variables.

• 27.
KTH, School of Engineering Sciences (SCI), Physics, Mathematical Physics. KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
Finding and solving Calogero-Moser type systems using Yang-Mills gauge theories1999In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 563, p. 506-532Article in journal (Refereed)
• 28.
KTH, Superseded Departments, Physics. KTH, School of Engineering Sciences (SCI).
Interacting fermions on non-commutative spaces: Exactly solvable quantum field theories in 2n+1 dimensions2003In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 654, no 3, p. 404-426Article in journal (Refereed)

I present a novel class of exactly solvable quantum field theories. They describe non-relativistic fermions on even-dimensional flat space, coupled to a constant external magnetic field and a four point interaction defined with the Groenewold-Moyal star product. Using Hamiltonian quantization and a suitable regularization, I show that these models have a dynamical symmetry corresponding to gl(infinity) circle plus gl(infinity) at the special points Btheta = I and Btheta = -I, where B and theta are the matrices defining the magnetic field and the star product, respectively. I construct all eigenvalues and eigenstates, of the many-body Hamiltonian at these special points. I argue that this solution cannot be obtained by any mean-field theory, i.e., the models describe correlated fermions. I also mention other possible interpretations of these models in solid state physics.

• 29. Leurent, Sebastien
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
Multiple zeta functions and double wrapping in planar N=4 SYM2013In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 875, no 3, p. 757-789Article in journal (Refereed)

Using the FiNLIE solution of the AdS/CFT Y-system, we compute the anomalous dimension of the Konishi operator in planar N = 4 SYM up to eight loops, i.e. up to the leading double wrapping order. At this order a non-reducible Euler Zagier sum, zeta(1,2.8), appears for the first time. We find that at all orders in perturbation, every spectral-dependent quantity of the Y-system is expressed through multiple Hurwitz zeta functions, hence we provide a Mathematica package to manipulate these functions, including the particular case of Euler-Zagier sums. Furthermore, we conjecture that only Euler Zagier sums can appear in the answer for the anomalous dimension at any order in perturbation theory. We also resum the leading transcendentality terms of the anomalous dimension at all orders, obtaining a simple result in terms of Bessel functions. Finally, we demonstrate that exact Bethe equations should be related to an absence of poles condition that becomes especially non-trivial at double wrapping.

• 30. Lindner, Manfred
KTH, Superseded Departments, Physics.
A combined treatment of neutrino decay and neutrino oscillations2001In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 607, no 02-jan, p. 326-354Article in journal (Refereed)

Neutrino decay in vacuum has often been considered as an alternative to neutrino oscillations. Because nonzero neutrino masses imply the possibility of both neutrino decay and neutrino oscillations, we present a model-independent formal treatment of these combined scenarios. For that, we show for the example of Majoron decay that in many cases decay products are observable and may even oscillate. Furthermore, we construct a minimal scenario in which we study the physical implications of neutrino oscillations with intermediate decays.

• 31. Lindner, Manfred
KTH, Superseded Departments, Physics.
Decays of supernova neutrinos2002In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 622, no 02-jan, p. 429-456Article in journal (Refereed)

Supernova neutrinos could be well-suited for probing neutrino decay, since decay may be observed even for very small decay rates or coupling constants. We will introduce an effective operator framework for the combined description of neutrino decay and neutrino oscillations for supernova neutrinos, which can especially take into account two properties: one is the radially symmetric neutrino flux, allowing a decay product to be re-directed towards the observer even if the parent neutrino had a different original direction of propagation. The other is decoherence because of the long baselines for coherently produced neutrinos. We will demonstrate how to use this effective theory to calculate the time-dependent fluxes at the detector. In addition, we will show the implications of a Majoron-like decay model. As a result, we will demonstrate that for certain parameter values one may observe some effects which could also mimic signals similar to the ones expected from supernova models, making it in general harder to separate neutrino and supernova properties.

• 32.
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
Non-vanishing boundary effects and quasi-first-order phase transitions in high dimensional Ising models2011In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 845, no 1, p. 120-139Article in journal (Refereed)

In order to gain a better understanding of the Ising model in higher dimensions we have made a comparative study of how the boundary, open versus cyclic, of a d-dimensional simple lattice, for d = 1,...,5, affects the behaviour of the specific heat C and its microcanonical relative, the entropy derivative -partial derivative S-2/partial derivative U-2. In dimensions 4 and 5 the boundary has a strong effect on the critical region of the model and for cyclic boundaries in dimension 5 we find that the model displays a quasi-first-order phase transition with a bimodal energy distribution. The latent heat decreases with increasing systems size but for all system sizes used in earlier papers the effect is clearly visible once a wide enough range of values for K is considered. Relations to recent rigorous results for high dimensional percolation and previous debates on simulation of Ising models and gauge fields are discussed.

• 33.
KTH, School of Engineering Sciences (SCI), Theoretical Physics. KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
Energy-pressure relation for low-dimensional gases2014In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 887, p. 216-245Article in journal (Refereed)

A particularly simple relation of proportionality between internal energy and pressure holds for scale-invariant thermodynamic systems (with Hamiltonians homogeneous functions of the coordinates), including classical and quantum - Bose and Fermi - ideal gases. One can quantify the deviation from such a relation by introducing the internal energy shift as the difference between the internal energy of the system and the corresponding value for scale-invariant (including ideal) gases. After discussing some general thermodynamic properties associated with the scale-invariance, we provide criteria for which the internal energy shift density of an imperfect (classical or quantum) gas is a bounded function of temperature. We then study the internal energy shift and deviations from the energy pressure proportionality in low-dimensional models of gases interpolating between the ideal Bose and the ideal Fermi gases, focusing on the Lieb-Liniger model in id and on the anyonic gas in 2d. In Id the internal energy shift is determined from the thermodynamic Bethe ansatz integral equations and an explicit relation for it is given at high temperature. Our results show that the internal energy shift is positive, it vanishes in the two limits of zero and infinite coupling (respectively the ideal Bose and the Tonks-Girardeau gas) and it has a maximum at a finite, temperature-depending, value of the coupling. Remarkably, at fixed coupling the energy shift density saturates to a finite value for infinite temperature. In 2d we consider systems of Abelian anyons and non-Abelian Chern-Simons particles: as it can be seen also directly from a study of the virial coefficients, in the usually considered hard-core limit the internal energy shift vanishes and the energy is just proportional to the pressure, with the proportionality constant being simply the area of the system. Soft-core boundary conditions at coincident points for the two-body wavefunction introduce a length scale, and induce a non-vanishing internal energy shift: the soft-core thermodynamics is considered in the dilute regime for both the families of anyonic models and in that limit we can show that the energy pressure ratio does not match the area of the system, opposed to what happens for hard-core (and in particular 2d Bose and Fermi) ideal anyonic gases.

• 34. Marboe, Christian
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Trinity College Dublin, Ireland; Bogolyubov Institute for Theoretical Physics, Ukraine.
Quantum spectral curve as a tool for a perturbative quantum field theory2015In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 899, p. 810-847Article in journal (Refereed)

An iterative procedure perturbatively solving the quantum spectral curve of planar N = 4 SYM for any operator in the sl(2) sector is presented. A mathematica notebook executing this procedure is enclosed. The obtained results include 10-loop computations of the conformal dimensions of more than ten different operators. We prove that the conformal dimensions are always expressed, at any loop order, in terms of multiple zeta-values with coefficients from an algebraic number field determined by the one-loop Baxter equation. We observe that all the perturbative results that were computed explicitly are given in terms of a smaller algebra: single-valued multiple zeta-values times the algebraic numbers.

• 35.
Natl Univ Singapore, Singapore 117548, Singapore..
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
When is holography consistent?2015In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 898, p. 197-219Article in journal (Refereed)

Holographic duality relates two radically different kinds of theory: one with gravity, one without. The very existence of such an equivalence imposes strong consistency conditions which are, in the nature of the case, hard to satisfy. Recently a particularly deep condition of this kind, relating the minimum of a probe brane action to a gravitational bulk action (in a Euclidean formulation), has been recognized; and the question arises as to the circumstances under which it, and its Lorentzian counterpart, is satisfied. We discuss the fact that there are physically interesting situations in which one or both versions might, in principle, not be satisfied. These arise in two distinct circumstances: first, when the bulk is not an Einstein manifold and, second, in the presence of angular momentum. Focusing on the application of holography to the quark-gluon plasma (of the various forms arising in the early Universe and in heavy-ion collisions), we find that these potential violations never actually occur. This suggests that the consistency condition is a "law of physics" expressing a particular aspect of holography.

• 36.
KTH, Superseded Departments, Physics.
A flavor symmetry model for bilarge leptonic mixing and the lepton masses2002In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 643, no 03-jan, p. 247-279Article in journal (Refereed)

We present a model for leptonic mixing and the lepton masses based on flavor symmetries and higher-dimensional mass operators. The model predicts bilarge leptonic mixing (i.e., the mixing angles theta(12) and theta(23) are large and the mixing angle theta(13) is small) and an inverted hierarchical neutrino mass spectrum. Furthermore, it approximately yields the experimental hierarchical mass spectrum of the charged leptons. The obtained values for the leptonic mixing parameters and the neutrino mass squared differences are all in agreement with atmospheric neutrino data, the Mikheyev-Smirnov-Wolfenstein large mixing angle solution of the solar neutrino problem, and consistent with the upper bound on the reactor mixing angle. Thus, we have a large, but not close to maximal, solar mixing angle theta(12), a nearly maximal atmospheric mixing angle theta(23), and a small reactor mixing angle theta(13). In addition, the model predicts theta(12) similar or equal to pi/4 - theta(13).

• 37.
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
KTH, School of Engineering Sciences (SCI), Theoretical Physics.
Extrinsic and intrinsic CPT asymmetries in neutrino oscillations2015In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 893, p. 482-500Article in journal (Refereed)

We reconsider the extrinsic and possible intrinsic CPT violation in neutrino oscillations, and point out an identity, i.e., A(alpha beta)(CP) = A(beta alpha)(CPT) + A(alpha beta)(T), among the CP, T, and CPT asymmetries in oscillations. For three-flavor oscillations in matter of constant density, the extrinsic CPT asymmetries A(ee)(CPT), A(e mu)(CPT), A(mu e)(CPT), and A(mu mu)(CPT) caused by Earth matter effects have been calculated in the plane of different neutrino energies and baseline lengths. It is found that two analytical conditions can be implemented to describe the main structure of the contours of vanishing extrinsic CPT asymmetries. Finally, without assuming intrinsic CPT symmetry in the neutrino sector, we investigate the possibility to constrain the difference of the neutrino CF-violating phase and the antineutrino one (delta) over bar using a low-energy neutrino factory and the super-beam experiment ESS nu SB. We find that \delta - (delta) over bar\ less than or similar to 0.35 pi in the former case and \delta - (delta) over bar\ less than or similar to 0.7 pi in the latter case can be achieved at the 3 sigma confidence level if delta = (delta) over bar = pi/2 is assumed.

• 38.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden.
Hawking evaporation time scale of topological black holes in anti-de Sitter spacetime2016In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 903, p. 387-399Article in journal (Refereed)

It was recently pointed out that if an absorbing boundary condition is imposed at infinity, an asymptotically anti-de Sitter Schwarzschild black hole with a spherical horizon takes only a finite amount of time to evaporate away even if its initial mass is arbitrarily large. We show that this is a rather generic property in AdS spacetimes: regardless of their horizon topologies, neutral AdS black holes in general relativity take about the same amount of time to evaporate down to the same size of order L, the AdS length scale. Our discussion focuses on the case in which the black hole has toral event horizon. A brief comment is made on the hyperbolic case, i.e. for black holes with negatively curved horizons.

• 39.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Sweden; National Taiwan University, Taiwan .
Cold black holes in the Harlow-Hayden approach to firewalls2015In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 891, p. 627-654Article in journal (Refereed)

Firewalls are controversial principally because they seem to imply departures from general relativistic expectations in regions of spacetime where the curvature need not be particularly large. One of the virtues of the Harlow-Hayden approach to the firewall paradox, concerning the time available for decoding of Hawking radiation emanating from charged AdS black holes, is precisely that it operates in the context of cold black holes, which are not strongly curved outside the event horizon. Here we clarify this point. The approach is based on ideas borrowed from applications of the AdS/CFT correspondence to the quark-gluon plasma. Firewalls aside, our work presents a detailed analysis of the thermodynamics and evolution of evaporating charged AdS black holes with flat event horizons. We show that, in one way or another, these black holes are always eventually destroyed in a time which, while long by normal standards, is short relative to the decoding time of Hawking radiation.

• 40.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
Laplace-Beltrami operator and exact solutions for branes2013In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 867, no 3, p. 763-778Article in journal (Refereed)

Proposed is a new approach to finding exact solutions of nonlinear p-brane equations in D-dimensional Minkowski space based on the use of various initial value constraints. It is shown that the constraints Delta((p))(x) over right arrow =0 and Delta((p))(x) over right arrow = -Lambda(t, sigma(r))(x) over right arrow give two sets of exact solutions.

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