arXiv subjects

Irina Ya. Aref'eva

Publications and source records attributed to Irina Ya. Aref'eva.

At least 19 recordsLinked to original sources

arXiv2026

Optimizing the dilaton potential in holographic QCD via phase-transition constraints

In bottom-up holographic QCD (HQCD), two primary approaches are commonly employed: the potential reconstruction method, where the background geometry is fixed a priori and the dilaton potential is derived, and the direct method, where the potential is specified explicitly. While the reconstruction method is highly effective for capturing the phenomenological properties of QCD under extreme conditions, a subtlety arises in that the reconstructed potential depends on the chosen holographic boundary conditions. To address this issue, we propose constructing a dilaton potential designed to reproduce the typical features of HQCD phase transitions obtained by the reconstruction method, rather than one derived solely from HQCD vacuum solution. Using a light-quark model as an example, we construct a potential that captures the principal features of the phase structure of this model. Its parameters are determined at zero chemical potential by minimizing the deviation between the temperature dependence on the horizon position in the direct and reconstructed models and by fitting to the same position of a critical endpoint (CEP). The resulting minimal-potential model satisfactorily recovers the physics of the light-quark model even at relatively small chemical potential. Specifically, it yields a first-order phase transition (FOPT) line close to those obtained from the reconstruction method. Additionally, the minimal-potential model reproduces a rising Cornell-like quark-antiquark potential up to the hadronic distance $\ell=1.5$ fm, which we use as a phenomenological finite-distance criterion for confinement. The location of the confinement/deconfinement crossover in this minimal-potential model is also close to its counterpart in the original light-quark model.

hep-th↗

arXiv2026

Lifshitz-like black branes in arbitrary dimensions and the third law of thermodynamics

In this paper we present a systematic construction of an(isotropic) black brane solutions in arbitrary spacetime dimensions $D$ in particular, with Lifshitz-like asymptotics. Two distinct holographic models are considered. The first model involves a scalar field with a potential coupled to two Maxwell fields, allowing for both electric and magnetic charges. The second model includes a scalar field, a Maxwell field, and a three-form field strength of a Kalb-Ramond field. For each model, exact solutions for the metric, scalar field, gauge fields, and coupling functions are derived, incorporating anisotropic scaling exponents and general warp factors, including Gaussian forms. The results generalize previously known five-dimensional anisotropic black brane solutions to arbitrary dimensions. We show that the third law of thermodynamics, which requires entropy to vanish as temperature approaches zero, is satisfied for a certain range of parameters in both models. However, for specific warp factors or coupling constants, the entropy-temperature relation exhibits non-monotonic or multi-valued behavior, suggesting the possibility of phase transitions and a violation of the third law.

hep-th↗

arXiv2026

Lifshitz-like Magnetic Black Branes: Third Law of Thermodynamics and the Null Energy Condition

We develop a procedure to solve Einstein-dilaton-Maxwell models in quadratures using the potential reconstruction approach. We then apply this procedure to three distinct models, examining both the null energy condition (NEC) and the validity of the third law of thermodynamics in each case. The explicit knowledge of the blackening function -- as opposed to relying solely on numerical data -- allows us to discuss the validity of the third law in detail. The three models considered are: (I) a 5D model with two Maxwell fields, featuring anisotropy specified by a Gaussian function and a Lifshitz function; (II) the same 5D model as in (I), but with anisotropy parametrized by two Lifshitz parameters; and (III) a 6D model with one 2-form and one 3-form field, with the metric parametrized by two Lifshitz parameters. We show that for models I and II the parameter regions, where both the NEC and the third law are satisfied, exhibit no correlation between the two conditions. In contrast, for model III the validity of the NEC implies the validity of the third law.

hep-th↗

arXiv2026

Spatial Wilson Loops and Energy Loss for Heavy Quarks in Magnetized HQCD Model

We investigate the effective potential and the string tension for the spatial Wilson loop (SWL) in hot dense QGP with two types of anisotropy, i.e. external magnetic field and spatial anisotropy, employing a holographic approach for the heavy quark model. In this approach, the string is extended in the 5th, holographic direction and has a turning point either on a dynamical wall (DW) configuration or on the horizon configuration in the 5th direction. We obtain the magnetic catalysis behavior for a phase transition between DW and horizon configuration of the string. The structure of the phase diagram does not depend on the boundary conditions choice for the dilaton field. Inclusion of the external magnetic field and spatial anisotropy enhance the string tension in the horizon configuration, namely drag force. For the spatially isotropic case $ν= 1$ at different magnetic field values the string tension is proportional to $T^2$ and is qualitatively consistent with lattice results. However, for the anisotropic case, $ν= 4.5$, it deviates from the quadratic term.

hep-th↗

arXiv2025

Jet Quenching in Holographic QCD as an Indicator of Phase Transitions in Anisotropic Regimes

In this paper, we employ the gauge/gravity duality to study jet quenching (JQ) phenomena in the quark-gluon plasma. For this purpose, we implement holographic QCD models constructed from an Einstein-Maxwell-dilaton gravity at finite temperature and finite chemical potential for light and heavy quarks. The models capture both the confinement and deconfinement phases of QCD and the first-order phase transitions. We calculate the JQ parameter in different models and compare them with the experimental data obtained in heavy-ions studies. In particular, we investigate how JQ, as a function of temperature $T$, chemical potential $μ$, and magnetic field $c_B$, serves as a probe for identifying first-order phase transitions within the $(T,μ,c_B)$ parameter space of holographic QCD. Particular attention is paid to the dependence of JQ on the parameter $ν$, which characterizes longitudinal versus transverse anisotropy relative to the heavy-ion collision axis. By analyzing the dependence of the JQ parameters on these thermodynamic variables, we map critical regions associated with phase boundaries. We compare our findings to earlier studies of the running coupling constant's behavior within the gauge-gravity duality framework. This approach provides new insights into the interplay between non-perturbative dynamics and phase structure in strongly coupled systems.

hep-th↗

arXiv2025

Holographic QCD Running Coupling for Heavy Quarks in Strong Magnetic Field

We investigate the influence of a magnetic field on the running coupling constant for a heavy-quark model in a bottom-up holographic approach. To achieve this, we employ a magnetized Einstein-Maxwell-dilaton background that captures the essential features of heavy quark dynamics. Similar to the light-quark model, the running coupling $α$ for heavy quarks decreases in the presence of a strong external magnetic field at fixed temperature and chemical potential. The key distinction between the light and heavy quark models lies in the locations of their respective phase transitions. However, near the 1st order phase transitions, the behavior of $α$ is analogous for both cases: $α$ exhibits jumps that depend on temperature, chemical potential, and magnetic field strength.

hep-th↗

arXiv2025

Beta-Functions and RG flows for Holographic QCD with Heavy and Light Quarks: Isotropic case

In a previous paper [arXiv:2402.14512v3], we investigated the dependence of the running coupling constant on temperature and chemical potential for holographic models of the light and heavy quarks, supported by an Einstein-dilaton-Maxwell action. In this paper, we study the dependence of the corresponding $β$-functions on the temperature and the chemical potential. As in the previous paper, we give special attention to the behavior of the $β$-functions near the 1st order phase transitions. We consider different types of boundary conditions for the dilaton. Only one of the possible boundary conditions yields results that agree with lattice calculations at zero chemical potential. The corresponding $β$-functions are negative and exhibit jumps at the 1st order phase transitions. We also show that the RG fluxes are invariant with respect to the choice of the boundary conditions and that our exact solutions for the light and heavy quarks are unstable, as expected, given their negative dilaton potentials.

hep-th↗

arXiv2025

Running Coupling for Holographic QCD with Heavy and Light Quarks: Isotropic case

We consider the running coupling constant in holographic models supported by Einstein-dilaton-Maxwell action for heavy and light quarks. To obtain the dependence of the running coupling constant $α$ on temperature and chemical potential we impose boundary conditions on the dilaton field that depend on the position of the horizon. We use two types of boundary conditions: a simple boundary condition with the dilaton field vanishing at the horizon and a boundary condition that ensures an agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the 1st order phase transitions in $(μ,T)$-plane does not depend on the dilaton boundary conditions for light and heavy quarks. At these phase transitions, the function $α$ undergoes jumps depending on temperature and chemical potential. We also show that for the second boundary conditions the running coupling decreases with a temperature increase, and the dependence on temperature and chemical potential both for light and heavy quarks is actually specified in QGP phase by functions of one variable, demonstrating in this sense auto-model behavior.

hep-th↗

arXiv2024

Black Holes, Cavities and Blinking Islands

Placing a black hole in a cavity provides a natural framework for exploring gravitational scales, thermodynamic instabilities, and effective gravity theories. In this paper, we examine the evolution of entanglement entropy and entanglement islands in a two-sided extension of the Schwarzschild black hole in a cavity. By introducing a reflecting boundary in the eternal black hole exteriors, we regulate the infrared modes of Hawking radiation, finding that the entanglement entropy eventually saturates at a constant value. This value can be lower than the black hole thermodynamic entropy, thus avoiding the Page formulation of the information paradox. Regarding entanglement islands, we identify a universal effect induced by the boundary, which we term the ``blinking island'' -- where the entanglement island temporarily disappears, resulting in a short-time information paradox.

hep-th↗

arXiv2024

Holographic QCD Running Coupling for Light Quarks in Strong Magnetic Field

We consider running coupling constant in holographic model with external magnetic field supported by Einstein-dilaton-three-Maxwell action. We obtain a significant dependence of the running coupling constant $α$ on chemical potential, temperature and magnetic field. We use the boundary condition that ensures the agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the 1st order phase transitions in $(μ, T)$-plane does not depend on the dilaton boundary conditions. We observe that running coupling $α$ decreases with increasing magnetic field for the fixed values of chemical potential and temperature. At the 1st order phase transitions the functions $α$ undergo jumps depending on temperature, chemical potential and magnetic field.

hep-th↗

arXiv2024

Einstein-dilaton-four-Maxwell Holographic Anisotropic Models

In recent literature on holographic QCD, the consideration of the five-dimensional Einstein-dilaton-Maxwell models has played a crucial role. Typically, one Maxwell field is associated with the chemical potential, while additional Maxwell fields are used to describe the anisotropy of the model. A more general scenario involves up to four Maxwell fields. The second field represents spatial longitudinal-transverse anisotropy, while the third and fourth fields describe anisotropy induced by an external magnetic field. We consider an ansatz for the metric characterized by four functions at zero temperature and five functions at non-zero temperature. Maxwell field related to the chemical potential is treated with the electric ansatz, as is customary, whereas the remaining three Maxwell fields are treated with a magnetic ansatz. We demonstrate that for the fully anisotropic diagonal metric only six out of the seven equations are independent. One of the matter equations -- either the dilaton or the vector potential equation -- follows from the Einstein equations and the remaining matter equation. This redundancy arises due to the Bianchi identity for the Einstein tensor and the specific form of the stress-energy tensor in the model. A procedure for solving this system of six equations is provided. This method generalizes previously studied cases involving up to three Maxwell fields. In the solution with three magnetic fields our analysis shows, that the dilaton equation is a consequence of the five Einstein equations and the equation for the vector potential

hep-th↗

arXiv2024

Beta-Function Dependence on Running Coupling in Holographic QCD Models

We study the dependence of beta-function on running coupling constant in holographic models supported by Einstein-dilaton-Maxwell action for light and heavy quarks. Although, in the previous paper [arXiv:2402.14512], we considered different types of the dilaton boundary conditions, but since the behavior of $β$-function as a function of running coupling does not depend significantly on the boundary condition, we chose one. The corresponding $β$-functions are negative and monotonically decreasing functions, and have jumps on the 1-st order phase transitions for both light and heavy quarks. In addition, we compare our holographic results for $β$-function as a function of running coupling with perturbation results that obtained within 2-loop calculations.

hep-th↗

arXiv2024

Magnetic Catalysis in Holographic Model with Two Types of Anisotropy for Heavy Quarks

In our previous paper [arXiv:2011.07023] we have constructed a twice anisotropic five-dimensional holographic model supported by Einstein-dilaton-three-Maxwell action that reproduced some essential features of the "heavy quarks" model. However, that model did not describe the magnetic catalysis (MC) phenomena expected from lattice results for the QGP made up from heavy quarks. In this paper we fill this gap and construct the model that improves the previous one. It keeps typical properties of the heavy quarks phase diagram, and meanwhile possesses the MC. The deformation of previous model includes the modification of the "heavy quarks" warp factor and the coupling function for the Maxwell field providing the non-trivial chemical potential.

hep-th↗

arXiv2022

Holographic model for light quarks in anisotropic hot dense QGP with external magnetic field

We present a five-dimensional twice anisotropic holographic model supported by Einstein-dilaton-three-Maxwell action describing light quarks. The first of the Maxwell fields provides finite chemical potential. The second Maxwell field serves for anisotropy, characterizing spatial anisotropy of the QGP produced in heavy-ion collisions (HIC). The third Maxwell field is related to a magnetic field that appears in HIC. The dependence of the 5-dim black hole solution and confinement/deconfinement phase diagram on this magnetic field is considered. The effect of the inverse magnetic catalyses for light quarks phase diagram is obtained. Positions of critical end points are found. We also study the behavior of the conductivity for light quarks in both isotropic and anisotropic cases and show that behaviour of the conductivity near critical points essentially depend on quark masses, meanwhile at high temperature they are similar.

hep-th↗

arXiv2022

Thermal density matrix breaks down the Page curve

In this paper, we study entanglement islands and the Page curve in the eternal four-dimensional Schwarzschild black hole surrounded by finite temperature conformal matter. By finite temperature conformal matter we mean the matter described by the thermal density matrix, rather than the usually considered matter above the Fock vacuum. We take the matter and the black hole at different temperatures and calculate the entanglement entropy for such a setup using the s-wave approximation. As a result, we obtain that at late times the island prescription leads to the exponential growth of the entanglement entropy of conformal matter in thermal vacuum.

hep-th↗

arXiv2022

Direct photons emission rate and electric conductivity in twice anisotropic QGP holographic model with first-order phase transition

The electric conductivity and direct photons emission rate are considered in the holographic theory with two types of anisotropy. The electric conductivity is derived in two different ways, and their equivalence for the twice anisotropic theory is shown. Numerical calculations of the electric conductivity were done for Einstein-dilaton-three-Maxwell holographic model [29]. The dependence of the conductivity on the temperature, the chemical potential, the external magnetic field, and the spatial anisotropy of the heavy-ions collision (HIC) is studied. The electric conductivity jumps near the first-order phase transition are observed. This effect is similar to the jumps of holographic entanglement that were studied previously.

hep-th↗

arXiv2021

On the nonclassicality in quantum JT gravity

In this note, we consider the question of classicality for the theory which is known to be the effective description of two-dimensional black holes - the Morse quantum mechanics. We calculate the Wigner function and the Fisher information characterizing classicality/quantumness of single-particle systems and briefly discuss further directions to study.

hep-th↗

arXiv2021

Holographic drag force in 5d Kerr-AdS black hole

We consider the 5d Kerr-AdS black hole as a gravity dual to rotating quark-gluon plasma. In the holographic prescription we calculate the drag force acting on a heavy quark. According to the holographic approach a heavy quark can be considered through the string in the gravity dual. We study the dynamics of the string for the Kerr-AdS backgrounds with one non-zero rotational parameter and two non-zero rotational parameters that are equal in magnitude. For the case of one non-zero rotational parameter we find good agreement with the prediction from the 4d case considered by arXiv:1012.3800).

hep-th↗