arXiv subjects

Sergei G. Ovchinnikov

Publications and source records attributed to Sergei G. Ovchinnikov.

7 recordsLinked to original sources

arXiv2026

Anisotropic drag force in finite-density QGP from charged rotating 5D black holes

We study the drag force acting on a heavy quark in a holographic plasma with rotational anisotropy and finite density. The bulk dual is the CCLP black hole of five-dimensional minimal gauged supergravity, characterised by two independent rotation parameters and electric charge. In the neutral Kerr--AdS limit, we use the principal Killing string to obtain an exact drag force for arbitrary rotation parameters. The resulting force is purely tangential but generically anisotropic, reducing to the viscous form only in the equal-spin sector. We then analyse stationary strings in the charged CCLP background perturbatively in the slow-rotation regime. A regularity analysis of the Lorentzian worldsheet fixes the angular integration constants that would otherwise remain ambiguous, yielding a finite renormalised transverse drag force with a smooth Kerr--AdS limit. We also show that, in the equal-spin sector, worldsheet regularity selects a unique co-rotating equilibrium quark and compute its renormalised free-energy shift.

hep-th↗

arXiv2025

All toric Kahler surfaces with twistor 2-forms

We complete the classification of all smooth 4-dimensional Kahler geometries admitting a twistor (conformal Killing-Yano) 2-form invariant under a 2-torus action. We establish that there are six geometrically distinct families, and we provide them in a simple form amenable to calculations and compute their curvature. We also find that for toric geometries the square norm of the twistor 2-form is quadratic in moment maps, and we are led to conjecture that this holds when less symmetry is present.

hep-th↗

arXiv2024

All separable supersymmetric AdS$_5$ black holes

We consider the classification of supersymmetric black hole solutions to five-dimensional STU gauged supergravity that admit torus symmetry. This reduces to a problem in toric Kähler geometry on the base space. We introduce the class of separable toric Kähler surfaces that unify product-toric, Calabi-toric and orthotoric Kähler surfaces, together with an associated class of separable 2-forms. We prove that any supersymmetric toric solution that is timelike, with a separable Kähler base space and Maxwell fields, outside a horizon with a compact (locally) spherical cross-section, must be locally isometric to the known black hole or its near-horizon geometry. An essential part of the proof is a near-horizon analysis which shows that the only possible separable Kähler base space is Calabi-toric. In particular, this also implies that our previous black hole uniqueness theorem for minimal gauged supergravity applies to the larger class of separable Kähler base spaces.

hep-th↗

arXiv2022

On the uniqueness of supersymmetric AdS$_5$ black holes with toric symmetry

We consider the classification of supersymmetric AdS$_5$ black hole solutions to minimal gauged supergravity that admit a torus symmetry. This problem reduces to finding a class of toric Kähler metrics on the base space, which in symplectic coordinates are determined by a symplectic potential. We derive the general form of the symplectic potential near any component of the horizon or axis of symmetry, which determines its singular part for any black hole solution in this class, including possible new solutions such as black lenses and multi-black holes. We find that the most general known black hole solution in this context, found by Chong, Cvetic, Lü and Pope (CCLP), is described by a remarkably simple symplectic potential. We prove that any supersymmetric and toric solution that is timelike outside a smooth horizon, with a Kähler base metric of Calabi type, must be the CCLP black hole solution or its near-horizon geometry.

hep-th↗

arXiv2021

Uniqueness of supersymmetric AdS$_5$ black holes with $SU(2)$ symmetry

We prove that any supersymmetric solution to five-dimensional minimal gauged supergravity with $SU(2)$ symmetry, that is timelike outside an analytic horizon, is a Gutowski-Reall black hole or its near-horizon geometry. The proof combines a delicate near-horizon analysis with the general form for a Kähler metric with cohomogeneity-1 $SU(2)$ symmetry. We also prove that any timelike supersymmetric soliton solution to this theory, with $SU(2)$ symmetry and a nut or a complex bolt, has a Kähler base with enhanced $U(1)\times SU(2)$ symmetry, and we exhibit a family of asymptotically AdS$_5/\mathbb{Z}_p$ solitons for $p \geq 3$ with a bolt in this class.

hep-th↗

arXiv2003

Spin fluctuations influence on quasiparticle spectrum of realistic p-d model

In the present work the multiband p-d model for $CuO_2$-layer is treated. It was shown that for the realistic set of parameters besides Zhang-Rice two-particle singlet there is non-negligible contribution of two-particle triplet state to the top of the valence band. Also shown, that to gain quantitative agreement with experimental data the minimal approximation should include the spin fluctuations beyond the Hubbard-I scheme. Quasiparticle spectrum, obtained in this approximation, is in fairly good agreement with ARPES data on Bi2212 High-$T_c$ compound.

cond-mat.str-el↗

arXiv2002

Electronic Properties of the Effective Singlet-Triplet Model

In present work the effective singlet-triplet model for CuO2-layer on the grounds of multiband p-d model of strongly correlated electrons is obtained. The resulting Hamiltonian has a form of generalized singlet-triplet t-t'-J model for p-type superconductors and form of usual t-t'-J model for n-type superconductors. In the mean field approximation in X-operator representation we derived equations for Gorkov type Green functions. The symmetry classification of the superconducting order parameter in case of tetragonal lattice resulted in d_{x^2-y^2}- and d_{xy}-types of singlet pairing for both p- and n-type superconductors while s-type singlet pairing don't take place. Also normal paramagnetic phase of effective singlet-triplet model was investigated and dispersion over Brillouin zone, density of states and evolution of Fermi level with doping were obtained.

cond-mat.supr-con↗