Operator lifetime and the force-free electrodynamic limit of magnetised holographic plasma

Poovuttikul, Napat; Rajagopal, Aruna

doi:10.1007/jhep09(2021)091

“…A similar situation appears in the context of relativistic spin hydrodynamics, where the spin current is not conserved, but at least for massive fermions, its relaxation can be made parametrically long by taking the non-relativistic limit of large fermion mass [89]. This is as well the case for magneto-hydrodynamics, in which the global U(1) electric symmetry is broken, and where both electric field and charge fluctuations relax in time [90,91] (see [24,92,93] for the holographic realizations).…”

Section: Discussionmentioning

confidence: 74%

U(1) quasi-hydrodynamics: Schwinger-Keldysh effective field theory and holography

Baggioli,

Bu,

Ziogas

2023

J. High Energ. Phys.

6

0

View full text Add to dashboard Cite

We study the quasi-hydrodynamics of a system with a softly broken U(1) global symmetry using effective field theory (EFT) and holographic methods. In the gravity side, we consider a holographic Proca model in the limit of small bulk mass, which is responsible for a controllable explicit breaking of the U(1) global symmetry in the boundary field theory. We perform a holographic Schwinger-Keldysh analysis, which allows us to derive the form of the boundary effective action in presence of dissipation. We compare our results with the previously proposed EFT and hydrodynamic theories, and we confirm their validity by computing the low-energy quasi-normal modes spectrum analytically and numerically. Additionally, we derive the broken holographic Ward identity for the U(1) current, and discuss the recently proposed novel transport coefficients for systems with explicitly broken symmetries. The setup considered is expected to serve as a toy model for more realistic situations where quasi-hydrodynamics is at work, such as axial charge relaxation in QCD, spin relaxation in relativistic systems, electric field relaxation in magneto-hydrodynamics, or momentum relaxation in condensed matter systems.

show abstract

“…A particular case that we did not address here is the T / √ ρ → 0 limit which is related to force-free electrodynamics (FFE) [11,[41][42][43][44]. As a first step, we would consider the strong magnetic field limit of the equation of state that we studied in sec.…”

Section: Discussionmentioning

confidence: 99%

A stable and causal model of magnetohydrodynamics

Armas¹,

Camilloni²

2022

Preprint

View full text Add to dashboard Cite

We formulate the theory of first-order dissipative magnetohydrodynamics in an arbitrary hydrodynamic frame under the assumption of parity-invariance and discrete charge symmetry. We study the mode spectrum of Alfvén and magnetosonic waves as well as the spectrum of gapped excitations and derive constraints on the transport coefficients such that generic equilibrium states with constant magnetic fields are stable and causal under linearised perturbations. We solve these constraints for a specific equation of state and show that there exists a large family of hydrodynamic frames that renders the linear fluctuations stable and causal. This theory does not require introducing new dynamical degrees of freedom and therefore is a promising and simpler alternative to Müller-Israel-Stewart-type theories. Together with a detailed analysis of transport, entropy production and Kubo formulae, the theory presented here is well suited for studying dissipative effects in various contexts ranging from heavy-ion collisions to astrophysics.

show abstract

“…A particular case that we did not address here is the T / √ ρ → 0 limit which is related to force-free electrodynamics (FFE) [12,[43][44][45][46]. As a first step, we would consider the strong magnetic field limit of the equation of state that we studied in section 4.…”

Section: Jcap10(2022)039mentioning

confidence: 99%

A stable and causal model of magnetohydrodynamics

Armas

¹

,

Camilloni

²

2022

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

We formulate the theory of first-order dissipative magnetohydrodynamics in an arbitrary hydrodynamic frame under the assumption of parity-invariance and discrete charge symmetry. We study the mode spectrum of Alfvén and magnetosonic waves as well as the spectrum of gapped excitations and derive constraints on the transport coefficients such that generic equilibrium states with constant magnetic fields are stable and causal under linearised perturbations. We solve these constraints for a specific equation of state and show that there exists a large family of hydrodynamic frames that renders the linear fluctuations stable and causal. This theory does not require introducing new dynamical degrees of freedom and therefore is a promising and simpler alternative to Müller-Israel-Stewart-type theories. Together with a detailed analysis of transport, entropy production and Kubo formulae, the theory presented here is well suited for studying dissipative effects in various contexts ranging from heavy-ion collisions to astrophysics.

show abstract

Operator lifetime and the force-free electrodynamic limit of magnetised holographic plasma

Cited by 5 publications

References 51 publications

U(1) quasi-hydrodynamics: Schwinger-Keldysh effective field theory and holography

U(1) quasi-hydrodynamics: Schwinger-Keldysh effective field theory and holography

A stable and causal model of magnetohydrodynamics

A stable and causal model of magnetohydrodynamics

Contact Info

Product

Resources

About