Plasma In External Magnetic Field Research Articles

QGP universality in a magnetic field?

We use top-down holographic models to study the thermal equation of state of strongly coupled quark-gluon plasma in external magnetic field. We identify different conformal and non-conformal theories within consistent truncations of mathcal{N} = 8 gauged supergravity in five dimensions (including STU models, gauged mathcal{N} = 2* theory) and show that the ratio of the transverse to the longitudinal pressure PT /PL as a function of T / sqrt{B} can be collapsed to a ‘universal’ curve for a wide range of the adjoint hypermultiplet masses m. We stress that this does not imply any hidden universality in magnetoresponse, as other observables do not exhibit any universality. Instead, the observed collapse in PT /PL is simply due to a strong dependence of the equation of state on the (freely adjustable) renormalization scale: in other words, it is simply a fitting artifact. Remarkably, we do uncover a different universality in mathcal{N} = 2* gauge theory in the external magnetic field: we show that magnetized mathcal{N} = 2* plasma has a critical point at Tcrit/ sqrt{B} which value varies by 2% (or less) as m/ sqrt{B} ∈ [0, ∞). At criticality, and for large values of m/ sqrt{B} , the effective central charge of the theory scales as ∝ sqrt{B} /m.

Parametric instabilities in shallow water magnetohydrodynamics of astrophysical plasma in external magnetic field

This article deals with magnetohydrodynamic (MHD) flows of a thin rotating layer of astrophysical plasma in external magnetic field. We use the shallow water approximation to describe thin rotating plasma layer with a free surface in a vertical external magnetic field. The MHD shallow water equations with external vertical magnetic field are revised by supplementing them with the equations that are consequences of the magnetic field divergence-free conditions and reveal the existence of third component of the magnetic field in such approximation providing its relation with the horizontal magnetic field. It is shown that the presence of a vertical magnetic field significantly changes the dynamics of the wave processes in astrophysical plasma compared to the neutral fluid and plasma layer in a toroidal magnetic field. The equations for the nonlinear wave packets interactions are derived using the asymptotic multiscale method. The equations for three magneto-Poincare waves interactions, for three magnetostrophic waves interactions, for the interactions of two magneto-Poincare waves and for one magnetostrophic wave and two magnetostrophic wave and one magneto-Poincare wave interactions are obtained. The existence of parametric decay and parametric amplifications is predicted. We found following four types of parametric decay instabilities: magneto-Poincare wave decays into two magneto-Poincare waves, magnetostrophic wave decays into two magnetostrophic waves, magneto-Poincare wave decays into one magneto-Poincare wave and one magnetostrophic wave, magnetostrophic wave decays into one magnetostrophic wave and one magneto-Poincare wave. Following mechanisms of parametric amplifications are found: parametric amplification of magneto-Poincare waves, parametric amplification of magnetostrophic waves, magneto-Poincare wave amplification in magnetostrophic wave presence and magnetostrophic wave amplification in magneto-Poincare wave presence. The instabilities growth rates are obtained respectively.

Relativistic conformal magneto-hydrodynamics from holography

We use the AdS/CFT correspondence to study first-order relativistic viscous magneto-hydrodynamics of (2+1)-dimensional conformal magnetic fluids. It is shown that the first order magneto-hydrodynamics constructed following Landau and Lifshitz from the positivity of the entropy production is inconsistent. We propose additional contributions to the entropy motivated dissipative current and, correspondingly, new dissipative transport coefficients. We use the strongly coupled M2-brane plasma in external magnetic field to show that the new magneto-hydrodynamics leads to self-consistent results in the shear and sound wave channels.