We investigate the behavior of energy momentum tensor correlators in holographic $\mathcal{N}=4$ super Yang-Mills plasma, taking finite coupling corrections into account. In the thermal limit we determine the flow of quasinormal modes as a function of the 't Hooft coupling. Then we use a specific model of holographic thermalization to study the deviation of the spectral densities from their thermal limit in an out-of-equilibrium situation. The main focus lies on the thermalization pattern with which the plasma constituents approach their thermal distribution as the coupling constant decreases from the infinite coupling limit. All obtained results point towards the weakening of the usual top-down thermalization pattern.
We studied the evolution of Wightman correlator in a thermalizing state modeled by AdS_3-Vaidya background. We gave a prescription for calculating Wightman correlator in coordinate space without using any approximation. For equal-time correlator $\langle O(v,x)O(v,0)\rangle$, we obtained an enhancement factor $v^2$ due to long range correlation present in the initial state. This was missed by previous studies based on geodesic approximation. We found that the long range correlation in initial state does not lead to significant modification to thermalization time as compared to known results wi…
Following a series of similar calculations in simpler non-conformal holographic setups, we determine the quasinormal mode spectrum for an operator dual to a gauge-invariant scalar field within the Improved Holographic QCD framework. At temperatures somewhat above the critical temperature of the deconfinement transition, we find a small number of clearly separated modes followed by a branch-cut-like structure parallel to the real axis, the presence of which is linked to the form of the IHQCD potential employed. The temperature dependence of the lowest nonzero mode is furthermore used to study t…
Holographic Thermalization with Chemical Potential
研究了在化学势存在下强耦合量子场论的热化问题。更准确地说，我们使用全息处方，计算了非局域算符，如两点函数，威尔逊圈和纠缠熵在一个时间相关的背景下，AdSd+1和AdSd+1 -Reissner-Nordström之间的插值d = 3，4。我们发现，正是纠缠熵使最新的量子态热化，从而为场论的平衡设定了时间尺度。我们研究了热化时间与探针长度和化学势的依赖关系。我们发现了一个有趣的非单调行为。当T1和μ/T都很小时，随着μ/T的增大，热化时间缩短，等离子体热化速度加快。当μ/T较大时，随μ/T的增加，依赖关系发生变化，热化时间增加。另一方面，如果我们增加T1的值，这种非单调行为变得不那么明显，并最终消失，表明热化物理学的两个不同的制度：热化时间对T1 < > 1的化学势的非单调依赖性< 1 and monotonic for T l >。
From the viewpoint of AdS/CFT correspondence, we investigate the holographic thermalization process in a four dimensional Einstein-Maxwell-axions gravity theory, which is considered as a simple bulk theory dual to a boundary theory with momentum relaxation. We probe the thermalization process using the equal time two-point functions and the entanglement entropy with the circle profile. We analyze the effects of momentum relaxation on the process in details and results show that the momentum relaxation gives longer thermalization time, which means it suppresses the holographic thermalization pr…
We investigate the effect of massive graviton on the holographic thermalization process. Before doing this, we first find out the generalized Vaidya-AdS solutions in the de Rham-Gabadadze-Tolley (dRGT) massive gravity by directly solving the gravitational equations. Then, we study the thermodynamics of these Vaidya-AdS solutions by using the Minsner-Sharp energy and unified first law, which also shows that the massive gravity is in a thermodynamic equilibrium state. Moreover, we adopt the two-point correlation function at equal time to explore the thermalization process in the dual field theor…
We propose a real time holographic framework to study thermalization processes of a family of QFT excited states. The construction builds on Skenderis-van Rees's holographic duals to QFT Schwinger-Keldysh complex-time ordered paths. Thermalization is explored choosing a set of observables $F_n$ which essentially isolate the excited state contribution. Focusing on theories defined on compact manifolds and with excited states defined in terms of Euclidean path integrals, we identify boundary conditions that allow to avoid any number of modes in the initial field state. In the large conformal dim…
On holographic thermalization and gravitational collapse of tachyonic scalar fields
本文研究了强耦合CFT中空间齐次系统的热化。非平衡初态是通过在Delta t >= t >= -Delta t期间接通CFT真空中的相关微扰而产生的。通过AdS/CFT，热化过程对应于AdS_5的庞加莱斑片中的一个快子标量场（m^2 = -3）的引力坍缩。在极限Δ t < 0.02/T时，发现热化时间t_T与文献[5]中讨论的由边缘微扰产生的非平衡态的热化时间t_T在数量上相同。在Delta t >= 1/T的情况下，我们也得到了双坍缩解，但在t = 0处有一个非平衡中间态.结果表明，在所有情况下，系统的热化都在一个典型的时间t_T ~ O（1）/T内。此外，还发现了一个守恒的能矩流，这有助于理解Poincare补丁中的坍缩过程与全局AdS中的坍缩过程的质的差异[9，10]。
We consider holographic thermalization in the presence of a Weyl correction in five dimensional AdS space. We first obtain the Weyl corrected black brane solution perturbatively, up to first order in the coupling. The corresponding AdS-Vaidya like solution is then constructed. This is then used to numerically analyze the time dependence of the two point correlation functions and the expectation values of rectangular Wilson loops in the boundary field theory, and we discuss how the Weyl correction can modify the thermalization time scales in the dual field theory. In this context, the subtle in…
We employ the holographic approach to study the thermalization in the quenched strongly-coupled field theories with very general anisotropic scalings including Lifshitz and hyperscaling violating fixed points. The holographic dual is a Vaidya-like time-dependent geometry where the asymptotic metric has general anisotropic scaling isometries. We find the Ryu-Takanayagi extremal surface and use it to calculate the time-dependent entanglement entropy between a strip region with width $2R$ and its outside region. In the special case with an isotropic metric, we also explore the entanglement entrop…
The thermalization process of the holographic entanglement entropy (HEE) of an annular domain is investigated over the Vaidya-AdS geometry. We numerically determine the Hubeny-Rangamani-Takayanagi (HRT) surface which may be a hemi-torus or two disks, depending on the ratio of the inner radius to the outer radius of the annulus. More importantly, for some fixed ratio of two radii, it undergoes a phase transition or double phase transitions from a hemi-torus configuration to a two-disk configuration, or vice versa, during the thermalization. The occurrence of various phase transitions is determi…
We perform a numerical study to recognize the difference between various massive potentials in the dRGT massive gravity on the holographic thermalization in the AdS and AdS Gauss-Bonnet gravities. The massive potential in $4+1$ dimensions includes three symmetric polynomial terms which we denote them as $a_1$, $a_2$ and $a_3$ terms. We observe, in the case of time evolution of entanglement entropy that there is a critical size of the entangling surface on the boundary below which both signs of $a_1$ and above the critical size $a_3$ are able to reduce the thermal value of entanglement entropy.…
In this paper we study the propagation of entanglement entropy after a global instantaneous quench on the CFT boundary of AdS bulk. We consider the Gauss-Bonnet model as a higher curvature gravity model for which we correct the RT(HRT) proposal to compute the holographic entanglement entropy(HEE). To obtain an analytical solution we perform an approximation approach which bounds our computations to the small subregions and we compare its thermalization regimes to the result of large subsystem case. We can see tsunami picture where the evolution of entanglement breaks down for the large systems…
Time dependent perturbations of states in the holographic dual of a 3+1 dimensional confining theory are considered. The perturbations are induced by varying the coupling to the theory's most relevant operator. The dual gravitational theory belongs to a class of Einstein-dilaton theories which exhibit a mass gap at zero temperature and a first order deconfining phase transition at finite temperature. The perturbation is realized in various thermal bulk solutions by specifying time dependent boundary conditions on the scalar, and we solve the fully backreacted Einstein-dilaton equations of moti…
We study the quasinormal modes and non-linear dynamics of a simplified model of semi-holography, which consistently integrates mutually interacting perturbative and strongly coupled holographic degrees of freedom such that the full system has a total conserved energy. We show that the thermalization of the full system can be parametrically slow when the mutual coupling is weak. For typical homogeneous initial states, we find that initially energy is transferred from the black brane to the perturbative sector, later giving way to complete transfer of energy to the black brane at a slow and cons…
We use a holographic method to investigate thermalization of a boost-invariant strongly interacting non-Abelian plasma. Boundary sourcing, a distorsion of the boundary metric, is employed to drive the system far from equilibrium. Thermalization is analyzed through nonlocal probes: the equal-time two-point correlation function of large conformal dimension operators in the boundary theory, and Wilson loops of different shapes. We study the dependence of the thermalization time on the size of the probes, and compare the results to the ones obtained using local observables: the onset of thermaliza…
We study the time evolution of the entanglement entropy of Hawking radiation in the $(n+1)-$dimensional Kerr-Newman black hole evaporation by the holographic approach that considering the $(n+1)-$dimensional AdS eternal black brane coupled to the auxiliary CFT reservoir is in the Hartle-Hawking state. The CFT reservoir itself has a holographic dual, the $(n+2)-$dimensional bulk geometry, and the original $(n+1)-$dimensional AdS-black brane is embedded into such bulk manifold, which is precisely Randall-Sundrum model. According to the island rule [1], the entanglement entropy in semi-classical …
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 orien…
