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Falkovsky L.A.,Landau Institute for Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics

The effects of phonon anharmonicity, phonon-magnon, and electron-phonon interactions on the temperature dependence of Raman optical phonon modes are theoretically investigated. Besides the Klemens result for the phonon width due to anharmonicity, the corresponding line shift is derived. We argue that the phonon decay into two magnons has very low intensity in ferromagnets with low Curie temperatures. Therefore, the electron interband transitions accompanied with the ferromagnetic ordering are included in considerations to get a good quantitative agreement with experiments. © 2013 American Physical Society. Source

Menshutin A.,Landau Institute for Theoretical Physics
Physical Review Letters

We present a self-consistent picture of diffusion limited aggregation (DLA) growth based on the assumption that the probability density P(r,N) for the next particle to be attached within the distance r to the center of the cluster is expressible in the scale-invariant form P[r/R dep(N)]. It follows from this assumption that there is no multiscaling issue in DLA and there is only a single fractal dimension D for all length scales. We check our assumption self-consistently by calculating the particle-density distribution with a measured P(r/R dep) function on an ensemble with 1000 clusters of 5×107 particles each. We also show that a nontrivial multiscaling function D(x) can be obtained only when small clusters (N<10000) are used to calculate D(x). Hence, multiscaling is a finite-size effect and is not intrinsic to DLA. © 2012 American Physical Society. Source

Alfimov M.N.,Moscow Institute of Physics and Technology | Tarnopolsky G.M.,Landau Institute for Theoretical Physics
Journal of High Energy Physics

In this paper we study the correspondence between the sû(n)k⊕ sû(n) p/ sû(n) k+p coset conformal field theories and N = 2 SU(n) gauge theories on ℝ 4/ℤ p. Namely we check the correspondence between the SU(2) Nekrasov partition function on ℝ 4/ℤ 4 and the conformal blocks of the S 3 parafermion algebra (in S and D modules). We find that they are equal up to the U(1)-factor as it was in all cases of AGT-like relations. Studying the structure of the instanton partition function on ℝ 4/ℤ 4 we also find some evidence that this correspondence with arbitrary p takes place up to the U(1)-factor. © 2012 SISSA. Source

Andreev O.,Ludwig Maximilians University of Munich | Andreev O.,Landau Institute for Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology

We make an estimate of the quadratic correction in the pressure of cold quark matter using gauge/string duality. © 2010 The American Physical Society. Source

Lebed A.G.,University of Arizona | Lebed A.G.,Landau Institute for Theoretical Physics
Physical Review Letters

We solve a long-standing problem about a theoretical description of the upper critical magnetic field, parallel to conducting layers and perpendicular to conducting chains, in a (TMTSF)2ClO4 superconductor. In particular, we explain why the experimental upper critical field, Hc2b ′6T, is higher than both the quasiclassical upper critical field and the Clogston paramagnetic limit. We show that this property is due to the coexistence of the hidden reentrant and Larkin-Ovchinnikov-Fulde-Ferrell phases in a magnetic field in the form of three plane waves with nonzero momenta of the Cooper pairs. Our results are in good qualitative and quantitative agreement with the recent experimental measurements of Hc2b′ and support a singlet d-wave-like scenario of superconductivity in (TMTSF) 2ClO4. © 2011 American Physical Society. Source

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