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Anastasia A. Golubtsova

Publications and source records attributed to Anastasia A. Golubtsova.

15 recordsLinked to original sources

Wigner continuous-spin equations in $\mathbf{AdS_D}$: bosonic and fermionic cases

We construct Wigner-like equations of motion for symmetric continuous-spin fields in anti-de Sitter space of arbitrary dimension, treating both the bosonic and fermionic cases. We generalise the classical flat-space Wigner constraints for bosonic continuous-spin fields, and for the fermionic case we adopt the equations proposed by Bekaert and Mourad as our starting point. This is achieved by covariantising the ordinary derivatives and deforming the resulting constraints so that they form a closed algebra. The construction is carried out in a metric-like formalism and yields a system of first-class constraints that define a representation of the $\mathfrak{so}(2,D-1)$ isometry algebra, realised via the Lie-Lorentz derivative. Using these constraints, we compute the eigenvalues of the quadratic and quartic Casimir operators and compare the obtained values with Metsaev's classification of continuous-spin representations for both the bosonic and fermionic cases. A crucial algebraic role is played by special operators of the (super)algebra Howe-dual to the Lorentz subalgebra $\mathfrak{so}(1,D-1)$: the $\mathfrak{sl}(2)$ Casimir operator in the bosonic case, and the Casimir's ghost of the $\mathfrak{osp}(1|2)$ superalgebra in the fermionic case. Both objects naturally organise the constraint algebra and ensure its consistency.

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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.

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Zoo of flows in a 3d gauged supergravity with periodic potential

In this paper we construct solutions with AdS/dS asymptotics for $D=3$ truncated gauged supergravity with a periodic scalar potential. In a holographic perspective, assuming Dirichlet boundary conditions, the solutions can be interpreted as deformations of 2d dual CFTs triggered by non-zero vacuum expectation values of irrelevant operators. In addition to the domain wall type solutions, we incorporated in the analysis a black string solution, which can also be interpreted as a deformation by VEV of an irrelevant operator. Generalizing the flows to finite temperature, we find that the corresponding geometries are singular but have horizons. For certain flows, we provide an analytical description near the horizon region. For an exact RG flow solution, we explicitly compute the Brown-York stress-energy tensor on a cutoff surface and show that the $T\overline{T}$ operator factorizes along the holographic RG flow. We also define an effective, scale-dependent deformation parameter $μ(ϕ)$, whose running is governed by the scalar field at the cutoff.

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Continuous spin field in the $\mathbf{AdS_6}$ space

A representation of the $\mathfrak{so}(2,5)$ algebra corresponding to the continuous spin field in $\mathbf{AdS_6}$ is considered. The algebra is realized using the Lie-Lorentz derivative, which naturally incorporates $\mathbf{AdS_6}$ geometry and spin degrees of freedom. Within this framework, we derive explicit expressions for the Casimir operators in terms of both the covariant derivative and the spin invariants. The continuous spin representation under consideration is defined by a system of operator constraints that generalize those known for six-dimensional Minkowski space. We demonstrate that these constraints completely fix all Casimir operators of the $\mathfrak{so}(2,5)$ algebra, with the eigenvalues determined by a dimensional real parameter $\boldsymbolμ$ and a positive (half-)integer $s$.

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More on thermal holographic RG flows in a 3D gauged supergravity

We continue our studies of holographic renormalization group (RG) flows for a 3d truncated supergravity model, the scalar potential of which can have either one or three extrema depending on the radius of the target manifold. We construct numerically and analytically thermal holographic RG flows, which are described by asymptotically AdS$_3$ black holes (non-rotating BTZ) characterized by the value of the scalar field on the horizon. We find two classes of RG flows with monotonic and non-monotonic behavior of the scalar field. The first one exists for both types of the potential, while the second one appears only for the potential with three extrema. For the slowly changing scalar field we find a special class of RG flows, which are described by the scalar field in the BTZ black hole geometry. For such flows we present an analytic solution for the scalar field from the horizon to the boundary. We discuss thermodynamical properties of the constructed holographic RG flows.

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Holographic RG flows and boundary conditions in a 3D gauged supergravity

In this work we focus on the study of RG flows of conformal field theories that are holographically dual to Poincaré domain wall solutions in $D=3$, $\mathcal{N}=(2,0)$ gauged supergravity coupled to a sigma model with target space $SU(1, 1)/U(1) = H^2$. This theory is truncated to a subsector where the vector field and phase of the scalar field vanish and we consider different boundary conditions for the remaining real scalar field. The RG flows, which are mostly non-superysymmetric, are analyzed by treating the supergravity field equations as a dynamical system for the scalar field and its derivative with respect to the scale factor. Phase diagrams are constructed for different values of the parameter $a^2$, which is related to the curvature of the scalar manifold. The behavior of solutions near the boundary is used to determine their type based on the expansion of the corresponding fake superpotential. By incorporating information on the boundary conditions, the obtained RG flows are interpreted using the holographic dictionary. Numerical solutions and plots of the fake superpotential are also provided.

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Probing the holographic model of $\mathcal{N} =4$ SYM rotating quark-gluon plasma

We study Wilson loops in holographic duals of the $\mathcal{N}=4$ SYM quark-gluon plasma. For this we consider the Schwarzschild-$AdS_5$ and Kerr-$AdS_5$ black holes, which are dual to the non-rotating and rotating QGPs, correspondingly. From temporal Wilson loops we find the heavy quark potentials in both backgrounds. For the temperature above the critical one we observe the Coulomb-like behaviour of the potentials. We find that increasing the rotation the interquark distance decreases, we also see that the increase of the temperature yields the similar behaviour. Moreover, at high temperatures values of the potentials in Kerr-$AdS_5$ are close to that one calculated in the Schwarzschild-$AdS_5$ black hole. We also explore holographic light-like Wilson loops from which the jet-quenching parameters of a fast parton propagating in the QGP are extracted. We find that the rotation increases the value of the jet-quenching parameter. However, at high temperatures the jet-quenching parameters have a cubic dependence on the temperature as for the AdS black brane.

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Stability analysis of holographic RG flows in 3d supergravity

We study holographic RG flows in a 3d supergravity model from the side of the dynamical system theory. The gravity equations of motion are reduced to an autonomous dynamical system. Then we find equilibrium points of the system and analyze them for stability. We also restore asymptotic solutions near the critical points. We find two types of solutions: with asymptotically AdS metrics and hyperscaling violating metrics. We write down possible RG flows between an unstable (saddle) UV fixed point and a stable (stable node) IR fixed point. We also analyze bifurcations in the model.

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Heavy quarks in rotating plasma via holography

We continue to explore the dynamics of a heavy quark in a strongly coupled rotating quark-gluon plasma within the holographic framework. We use the 5d Kerr-AdS black hole with two arbitrary rotating parameters to describe the rotating quark-gluon plasma. We present the relations for the drag force acting on the heavy quark both in the rotating- and static-at-infinity frames for arbitrary choice of the rotational parameters. We also calculate the thermal mass of a static quark in different frames and show that at high-$T$ limit the dependence on rotation is suppressed.

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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).

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Wilson loops in exact holographic RG flows at zero and finite temperature

We study rectangular timelike Wilson loops at long distances in the exact renormalization group flow in the context of the holographic duality. We consider the 5d holographic model with an exponential dilaton potential constructed in [arXiv:1803.06764]. To probe the RG flow backgrounds at zero and finite temperatures we calculate the minimal surfaces of the corresponding string worldsheets. We show that a holographic RG flow at $T=0$, that mimics QCD behaviour of the running coupling, has a confining phase at long distances, while the RG flow with an AdS UV fixed point is non-confining.

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Exact holographic RG flows and the $A_{1}\times A_{1}$ Toda chain

We construct analytic solutions of Einstein gravity coupled to a dilaton field with a potential given by a sum of two exponentials, by rewriting the equations of motion in terms of an integrable Toda chain. These solutions can be interpreted as domain walls interpolating between different asymptotics, and as such they can have interesting applications in holography. In some cases, we can construct a solution which interpolates between an AdS fixed point in the UV limit and a hyperscaling violating boundary in the IR region. We also find analytic black brane solutions at finite temperature. We discuss the properties of the solutions and the interpretation in terms of RG flow.

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T-duality and entanglement entropy for NS five-branes

In this work an algorithm is proposed to calculate entropy for field theories living on NS five branes, which gives a result invariant under T-duality. This is a deformation of the well known Ryu-Takayanagi formula, which takes into account dependence of localized backgrounds for the branes on winding modes of strings.

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Thermalization of holographic Wilson loops in spacetimes with spatial anisotropy

In this paper, we study behaviour of Wilson loops in the boost-invariant nonequilibrium anisotropic quark-gluon plasma produced in heavy-ion collisions within the holographic approach. We describe the thermalization studying the evolution of the Vaidya metric in the boost-invariant and spatially anisotropic background. To probe the system during this process we calculate rectangular Wilson loops oriented in different spatial directions. We find that anisotropic effects are more visible for the Wilson loops lying in the transversal plane unlike the Wilson loops with partially longitudinal orientation. In particular, we observe that the Wilson loops can thermalizes first unlike to the order of the isotropic model. We see that Wilson loops on transversal contours have the shortest thermalization time. We also calculate the string tension and the pseudopotential at different temperatures for the static quark-gluon plasma. We show that the pseudopotential related to the configuration on the transversal plane has the screened Cornell form. We also show that the jet-quenching parameter related with the average of the light-like Wilson loop exhibits the dependence on orientations.

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Analytic black branes in Lifshitz-like backgrounds and thermalization

Using black brane solutions in 5d Lifshitz-like backgrounds with arbitrary dynamical exponent $ν$, we construct the Vaidya geometry, asymptoting to the Lifshitz-like spacetime, which represents a thin shell infalling at the speed of light. We apply the new Lifshitz-Vaidya background to study the thermalization process of the quark-gluon plasma via the thin shell approach previously successfully used in several backgrounds. We find that the thermalization depends on the chosen direction because of the spatial anisotropy. The plasma thermalizes thus faster in the transversal direction than in the longitudinal one. To probe the system described by the Lifshitz-like backgrounds, we also calculate the holographic entanglement entropy for the subsystems delineated along both transversal and longitudinal directions. We show that the entropy has some universality in the behavior for both subsystems. At the same time, we find that certain characteristics strongly depend on the critical exponent $ν$.

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