arXiv subjects

H. Soltanpanahi

Publications and source records attributed to H. Soltanpanahi.

5 recordsLinked to original sources

arXiv2021

QNEC2 in deformed holographic CFTs

We use the quantum null energy condition in strongly coupled two-dimensional field theories (QNEC2) as diagnostic tool to study a variety of phase structures, including crossover, second and first order phase transitions. We find a universal QNEC2 constraint for first order phase transitions with kinked entanglement entropy and discuss in general the relation between the QNEC2-inequality and monotonicity of the Casini-Huerta c-function. We then focus on a specific example, the holographic dual of which is modelled by three-dimensional Einstein gravity plus a massive scalar field with one free parameter in the self-interaction potential. We study translation invariant stationary states dual to domain walls and black branes. Depending on the value of the free parameter we find crossover, second and first order phase transitions between such states, and the c-function either flows to zero or to a finite value in the infrared. Strikingly, evaluating QNEC2 for ground state solutions allows to predict the existence of phase transitions at finite temperature.

hep-th↗

arXiv2021

Critical behaviour of hydrodynamic series

We investigate the time-dependent perturbations of strongly coupled $\mathcal{N} = 4$ SYM theory at finite temperature and finite chemical potential with a second order phase transition. This theory is modelled by a top-down Einstein-Maxwell-dilaton description which is a consistent truncation of the dimensional reduction of type IIB string theory on AdS$_5\times$S$^5$. We focus on spin-1 and spin-2 sectors of perturbations and compute the linearized hydrodynamic transport coefficients up to the third order in gradient expansion. We also determine the radius of convergence of the hydrodynamic mode in spin-1 sector and the lowest non-hydrodynamic modes in spin-2 sector. Analytically, we find that all the hydrodynamic quantities have the same critical exponent near the critical point $θ= 1/2$. Moreover, we establish a relation between symmetry enhancement of the underlying theory and vanishing the only third order hydrodynamic transport coefficient $θ_1$, which appears in the shear dispersion relation of a conformal theory on a flat background.

hep-th↗

arXiv2012

CFT Duals of Black Rings With Higher Derivative Terms

We study possible CFT duals of supersymmetric five dimensional black rings in the presence of supersymmetric higher derivative corrections to the N=2 supergravity action. A Virasoro algebra associated to an asymptotic symmetry group of solutions is defined by using the Kerr/CFT approach. We find the central charge and compute the microscopic entropy which is in precise agreement with the macroscopic entropy. Although apparently related to a different aspect of the near-horizon geometry and a different Virasoro algebra, we find that the c-extremization method leads to the same central charge and microscopic entropy computed in the Kerr/CFT approach. The relationship between these two point of view is clarified by relating the geometry to a self-dual orbifold of AdS3.

hep-th↗

arXiv2009

5D Extremal Rotating Black Holes and CFT duals

Kerr/CFT correspondence has been recently applied to various types of 5D extremal rotating black holes. A common feature of all such examples is the existence of two chiral CFT duals corresponding to the U(1) symmetries of the near horizon geometry. In this paper, by studying the moduli space of the near horizon metric of five dimensional extremal black holes which are asymptotically flat or AdS, we realize an SL(2,Z) modular group which is a symmetry of the near horizon geometry. We show that there is a lattice of chiral CFT duals corresponding to the moduli points identified under the action of the modular group. The microscopic entropy corresponding to all such CFTs are equivalent and are in agreement with the Bekenstein-Hawking entropy.

hep-th↗

arXiv2009

Near the horizon of 5D black rings

For the five dimensional N=2 black rings, we study the supersymmetry enhancement and identify the global supergroup of the near horizon geometry. We show that the global part of the supergroup is OSp(4*|2)X U(1) which is similar to the small black string. We show that results obtained by applying the entropy function formalism, the c-extremization approach and the Brown-Henneaux method to the black ring solution are in agreement with the microscopic entropy calculation.

hep-th↗