QGP universality in a magnetic field?

Abstract

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 $\mathcal{N}=2^{\ast }$ theory) and show that the ratio of the transverse to the longitudinal pressure $P_T/P_L$ 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 $P_T/P_L$ 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 $\mathcal{N}=2^{\ast }$ gauge theory in the external magnetic field: we show that magnetized $\mathcal{N}=2^{\ast }$ plasma has a critical point at $T_{crit}/\sqrt{B}$ which value varies by $2\%$ (or less) as $m/\sqrt{B}\in [0,\infty )$. At criticality, and for large values of $m/\sqrt{B}$, the effective central charge of the theory scales as $\propto \sqrt{B}/m$.

42 pages, 8 figures; v2: JHEP version

References in corpus (9)

• Bulk viscosity of gauge theory plasma at strong coupling
• The QCD equation of state in background magnetic fields
• The black hole in the throat - thermodynamics of strongly coupled cascading gauge theories
• Equilibration rates in a strongly coupled nonconformal quark-gluon plasma
• Thermodynamics of the N=2^* strongly coupled plasma
• Supersymmetric Charged Clouds in AdS_5
• Holographic line defects in F(4) gauged supergravity
• Higher dimensional conformal field theories in the Coulomb branch
• Critical phenomena in N=2* plasma

Cited by in corpus (2)

• A bestiary of black holes on the conifold with fluxes
• Gravitational susceptibility of QGP