Linearized nonequilibrium dynamics in nonconformal plasma

Janik, Romuald A.; Plewa, Grzegorz; Soltanpanahi, Hesam; Spaliński, Michał

doi:10.1103/physrevd.91.126013

Cited by 50 publications

(88 citation statements)

References 34 publications

(86 reference statements)

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“…We note that this universal behavior only applies to critical theories with no mass gap. Holographic equilibration in gapped theories such as QCD has also been studied in the literature [14,26,31], where the approach to equilibrium may be qualitatively different [14].…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

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Holographic Equilibration of Nonrelativistic Plasmas

et al. 2016

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We study far-from-equilibrium physics of strongly interacting plasmas at criticality and zero charge density for a wide range of dynamical scaling exponents z in d dimensions using holographic methods. In particular, we consider homogeneous isotropization of asymptotically Lifshitz black branes with full backreaction. We find stable evolution and equilibration times that exhibit small dependence of z and are of the order of the inverse temperature. Performing a quasinormal mode analysis, we find a corresponding narrow range of relaxation times, fully characterized by the fraction z=ðd − 1Þ. For z ≥ d − 1, equilibration is overdamped, whereas for z < d − 1, we find oscillatory behavior. Finally, and most interestingly, we observe that also the nonlinear evolution, although differing significantly from a quasinormal mode fit, is to a high degree of precision characterized by the fraction z=ðd − 1Þ. Introduction.-Quantum criticality has been a focus of interest both in theoretical and experimental physics over the past few decades. It is believed to be a key ingredient in the solution to the various yet unsolved problems such as the high T c superconductivity [1]. In particular, the dynamics of a system near a continuous quantum phase transition is governed by a universal, scale invariant theory characterized by the dimensionality d, the dynamical scaling exponent z, and the various other critical exponents that are independent of the microscopic Hamiltonian of the system. In these systems, the characteristic energy scale Δ, such as the gap separating the first excited state from the ground state, vanishes as the correlation length ξ diverges as Δ ∼ ξ −z . For instance, z ¼ 1 occurs at the touching points of the band structure of monolayer graphene, z ¼ 2 can describe the case of bilayer graphene, and z ¼ 2, 3 occur in heavy fermion systems; see, e.g., Refs. [2][3][4][5][6].The existence of a quantum critical point at vanishing temperature determines the behavior of observables also at finite temperature, and even beyond the thermal equilibrium, in the so-called quantum critical region of the parameter space. In fact, a basic way to characterize this quantum critical region is to consider the response of the system to a small disturbance, determined by the equilibration time τ eq [7]. The quantum critical region corresponds to short relaxation times τ eq ∼ 1=T [8], whereas local equilibrium is reached much more slowly as τ eq ≫ 1=T outside the quantum critical region [1].In this Letter, we want to go one step further and ask the question, what happens when such a quantum critical system is taken completely out of equilibrium, when the perturbation is not small, but of the same order as the Hamiltonian? We answer this question partially in the particular situation when the collective excitations of the system are characterized by global, hydrodynamic

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Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

“…Furthermore, turning on either a mass or momentum for the QNM will also break the dependence on α alone. To compute QNMs we solve the associated generalized eigenvalue equation using pseudospectral methods [26]. We compare the nonlinear evolution with the sum of the first 10 QNMs, B QNM ðu; tÞ ¼ Re P 9 i¼0 c i b i ðuÞe −iω i t .…”

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confidence: 99%

Holographic Equilibration of Nonrelativistic Plasmas

et al. 2016

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“…In [22] they consider holographic models with an equation of state inspired by lattice QCD, and study the behavior of the lowest non-hydrodynamical quasinormal mode. Again they find a moderate dependence of the damping of the mode on the conformal breaking, by a factor of about two between the extreme cases.…”

Section: Jhep01(2016)134mentioning

confidence: 99%

Late time behavior of non-conformal plasmas

Gürsoy

Järvinen

Policastro

2016

J. High Energ. Phys.

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Abstract:We study the dependence of the approach to thermal equilibrium of strongly coupled plasmas on the breaking of scale invariance. The theories we consider are the holographic duals to Einstein gravity coupled to a scalar with an exponential potential. The coefficient in the exponent, X, is the parameter that controls the deviation from the conformally invariant case. For these models we obtain analytic solutions for the plasma expansion in the late-time limit, under the assumption of boost-invariance, and we determine the scaling behaviour of the energy density, pressure, and temperature as a function of time, which is found to agree with the hydrodynamical expectation. We find that the temperature decays as a function of proper time as T ∼ τ −s/4 with s determined in terms of the non-conformality parameter X as s = 4(1 − 4X 2 )/3. This agrees with the result of Janik and Peschanski, s = 4/3, for the conformal plasmas and generalizes it to non-conformal plasmas with X = 0. We also consider more realistic potentials where the exponential is supplemented by power-law terms. Even though in this case we cannot have exact solutions, we are able under certain assumptions to determine the scaling of the energy, that receives logarithmic corrections.

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“…This work and most of the subsequent developments focused on thermalization and out-of equilibrium physics in conformal rather than non-conformal plasmas. The latter only started attracting attention recently with the works [124,125,126,127,128,129,130,131,132]. We have not reviewed these developments in this review due to lack of space.…”

Section: Conclusion and A Look Aheadmentioning

confidence: 99%

Improved Holographic QCD and the Quark--Gluon Plasma

Gürsoy¹

2016

Acta Phys. Pol. B

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We review construction of the improved holographic models for QCDlike confining gauge theories and their applications to the physics of the Quark-gluon plasma. We also review recent progress in this area of research. The lecture notes start from the vacuum structure of these theories, then develop calculation of thermodynamic and hydrodynamic observables and end with more advanced topics such as the holographic QCD in the presence of external magnetic fields. This is a summary of the lectures presented at

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Linearized nonequilibrium dynamics in nonconformal plasma

Cited by 50 publications

References 34 publications

Holographic Equilibration of Nonrelativistic Plasmas

Holographic Equilibration of Nonrelativistic Plasmas

Late time behavior of non-conformal plasmas

Improved Holographic QCD and the Quark--Gluon Plasma

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