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Lukyanov S.L.,Rutgers University | Lukyanov S.L.,Ld Landau Institute For Theoretical Physics
Nuclear Physics B | Year: 2012

We construct a zero-curvature representation for a four-parameter family of non-linear sigma models with a Kalb-Ramond term. The one-loop renormalization is performed that gives rise to a new set of ancient and eternal solutions to the Ricci flow with torsion. Our analysis provides an explicit illustration of the role of the dilaton field for the renormalization of the non-linear sigma model. © 2012 .


Falkovsky L.A.,Ld Landau Institute For Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The conductivity of graphite is analytically evaluated in the range of 0.1-1.5 eV, where the electron relaxation processes can be neglected and the low-energy excitations at the "Dirac" points are most essential. The value of conductivity calculated per one graphite layer is close to the universal conductivity of graphene. The features of the conductivity are explained in terms of singularities of the electron dispersion in graphite. © 2010 The American Physical Society.


Zakharov B.G.,Ld Landau Institute For Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We study the electromagnetic response of the quark-gluon plasma in AA-collisions at RHIC and LHC energies for a realistic space-time evolution of the plasma fireball. We demonstrate that for a realistic electric conductivity the electromagnetic response of the plasma is in a quantum regime when the induced electric current does not generate a classical electromagnetic field, and can only lead to a rare emission of single photons. © 2014.


Andreev O.,Ld Landau Institute For Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We use gauge/string duality to model some hybrid heavy-quark potentials. The potentials under consideration cannot be described by a single Nambu-Goto string. This is why we call them "exotic." For Σu-, the result is in quite good agreement with lattice simulations. © 2012 American Physical Society.


Zakharov B.G.,Ld Landau Institute For Theoretical Physics
Physical Review Letters | Year: 2014

We study modification of the photon-tagged and inclusive jets in pp collisions at s=7 TeV due to mini-quark-gluon plasma which can be produced in high multiplicity events. We show that for underlying events with dNch/dη∼20-60 the medium effects lead to a considerable modification of the photon-tagged and inclusive jet fragmentation functions. For inclusive jets, the magnitude of the effect is surprisingly large. The effect is quite strong even for typical underlying events. We find that the spectrum of charged hadrons is suppressed by ∼35%-40% at pT∼5-10 GeV. © 2014 American Physical Society.


Volovik G.E.,Ld Landau Institute For Theoretical Physics
Lecture Notes in Physics | Year: 2013

Topology in momentum space is the main characteristic of the ground state of a system at zero temperature, the quantum vacuum. The gaplessness of fermions in bulk, on the surface or inside the vortex core is protected by topology, and is not sensitive to the details of the microscopic physics (atomic or trans-Planckian). Irrespective of the deformation of the parameters of the microscopic theory, the energy spectrum of these fermions remains strictly gapless. This solves the main hierarchy problem in particle physics: for fermionic vacua with Fermi points the masses of elementary particles are naturally small. The quantum vacuum of the Standard Model is one of the representatives of topological matter alongside with topological superfluids and superconductors, topological insulators and semi-metals, etc. There is a number of topological invariants in momentum space of different dimensions. They determine the universality classes of the topological matter and the type of the effective theory which emerges at low energy. In many cases they also give rise to emergent symmetries, including the effective Lorentz invariance, and emergent phenomena such as effective gauge and gravitational fields. The topological invariants in extended momentum and coordinate space determine the bulk-surface and bulk-vortex correspondence. They connect the momentum space topology in bulk with the real space. These invariants determine the gapless fermions living on the surface of a system or in the core of topological defects (vortices, strings, domain walls, solitons, monopoles, etc.). The momentum space topology gives some lessons for quantum gravity. In effective gravity emerging at low energy, the collective variables are the tetrad field and spin connections, while the metric is the composite object of tetrad field. This suggests that the Einstein-Cartan-Sciama-Kibble theory with torsion field is more relevant. There are also several scenarios of Lorentz invariance violation governed by topology, including splitting of Fermi point and development of the Dirac points with quadratic and cubic spectrum. The latter leads to the natural emergence of the Hořava-Lifshitz gravity. © Springer International Publishing Switzerland 2013.


Andreev O.,Ld Landau Institute For Theoretical Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016

We use gauge-string duality to model the N-quark potential in pure Yang-Mills theories. For SU(3), the result agrees remarkably well with lattice simulations. The model smoothly interpolates between almost the δ-law at short distances and the Y-law at long distances. © 2016 The Author.


Andreev O.,Ld Landau Institute For Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

We analytically evaluate the expectation value of a baryonic Wilson loop in a holographic model of an SU(3) pure gauge theory. We then discuss three aspects of a static three-quark potential: an aspect of universality which concerns properties independent of a geometric configuration of quarks, a heavy diquark structure, and a relation between the three- and two-quark potentials. © 2016 American Physical Society.


Falkovsky L.A.,Ld Landau Institute For Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The optical conductivity of graphite in quantizing magnetic fields is studied. Both the dynamical conductivities, longitudinal as well as Hall's, are analytically evaluated. The conductivity peaks are explained in terms of electron transitions. We have shown that the trigonal warping in graphite can be considered within the perturbation theory at strong magnetic fields larger than approximately 1 T. The main optical transitions obey the selection rule with Δn=1 for the Landau number n, however, the Δn=2 transitions due to the trigonal warping with small probability are also essential. The Kerr rotation and reflectivity in graphite in the quantizing magnetic fields are calculated. Parameters of the Slonczewski-Weiss-McClure model are used in the fit taking into account the previous dHvA measurements and correcting some of them for the case of strong magnetic fields. © 2011 American Physical Society.


Falkovsky L.A.,Ld Landau Institute For Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The optical conductivity of graphite in quantizing magnetic fields is analytically evaluated for frequencies in the range of 10-300 meV, where the electron relaxation processes can be neglected and the low-energy excitations at the "Dirac lines" are more essential. The conductivity peaks are explained in terms of the electron transitions in graphite. Conductivity calculated per one graphite layer tends, on average, to the universal conductivity of graphene. The (semi)metal-insulator transformation is possible under doping in high magnetic fields. © 2011 American Physical Society.

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