QCD phase transition in a strong magnetic background

The D3/D7 system holographically describes an N =2 gauge theory which spontaneously breaks a chiral symmetry by the formation of a quark condensate in the presence of a magnetic field. At finite temperature it displays a first order phase transition. We study out of equilibrium dynamics associated with this transition by placing probe D7 branes in a geometry describing a boost-invariant expanding or contracting plasma. We use an adiabatic approximation to track the evolution of the quark condensate in a heated system and reproduce the phase structure expected from equilibrium dynamics. We then study solutions of the full partial differential equation that describes the evolution of out of equilibrium configurations to provide a complete description of the phase transition including describing aspects of bubble formation.

Section: Jhep01(2011)050supporting

confidence: 80%

Non-equilibrium physics at a holographic chiral phase transition

Evans

Kalaydzhyan

Kim

et al. 2011

“…Lattice studies [53] of the effect of a baryon chemical potential in the deconfined phase, when the system is not asymptotically weakly coupled, claim to find measurable sensitivity in the Debye screening length, comparable to perturbative estimates, but with quite large error bars. Lattice QCD studies of magnetoresponse [29][30][31][32] also find substantial changes in thermodynamics when the magnetic field energy density becomes large compared to T 4 . Consequently, when this work on strongly coupled N = 4 SYM plasma was initiated, we expected to find significant changes in equilibration dynamics when a conserved charge density is added to the plasma, or when the system is placed in a background magnetic field.…”

Section: Jhep07(2015)116 6 Conclusionmentioning

confidence: 99%

“…A growing body of work [24][25][26][27][28] suggests that electromagnetic effects may play a significant role despite the small value of the fine structure constant. Electromagnetic effects on equilibrium QCD properties are also under study using lattice gauge theory [29][30][31][32].…”

Section: Jhep07(2015)116mentioning

confidence: 99%

Far-from-equilibrium dynamics of a strongly coupled non-Abelian plasma with non-zero charge density or external magnetic field

Fuini

Yaffe

2015

144

Using holography, we study the evolution of a spatially homogeneous, far from equilibrium, strongly coupled N = 4 supersymmetric Yang-Mills plasma with a non-zero charge density or a background magnetic field. This gauge theory problem corresponds, in the dual gravity description, to an initial value problem in Einstein-Maxwell theory with homogeneous but anisotropic initial conditions. We explore the dependence of the equilibration process on different aspects of the initial departure from equilibrium and, while controlling for these dependencies, examine how the equilibration dynamics are affected by the presence of a non-vanishing charge density or an external magnetic field. The equilibration dynamics are remarkably insensitive to the addition of even large chemical potentials or magnetic fields; the equilibration time is set primarily by the form of the initial departure from equilibrium. For initial deviations from equilibrium which are well localized in scale, we formulate a simple model for equilibration times which agrees quite well with our results.

“…At zero µ B and finite B, there is no sign problem and so one can calculate the phase diagram in the T, B plane using Monte-Carlo methods. Recent lattice calculations [6,7] suggest that for physical quark masses, the transition temperature for the chiral transition is a decreasing function of the magnetic field B, while for larger values of the quark masses corresponding to m π ≃ 400 MeV, the temperature is an increasing function of B [8,9]. The qualitative behavior of the transition temperature for physical quark masses is in disagreement with model calculations using either the (Polyakov-loop extended) Nambu-Jona-Lasinio ((P)NJL) model or the (Polyakov-loop extended) quarkmeson model ((P)QM); in these models, the critical temperature is an increasing function of the magnetic field, see e.g.…”

Section: Introductionmentioning

confidence: 99%

Chiral and deconfinement transitions in a magnetic background using the functional renormalization group with the Polyakov loop

Andersen

Naylor

Tranberg

2014

We use the Polyakov loop coupled quark-meson model to approximate low energy QCD and present results for the chiral and deconfinement transitions in the presence of a constant magnetic background B at finite temperature T and baryon chemical potential µ B . We investigate effects of various gluonic potentials on the deconfinement transition with and without a fermionic backreaction at finite B. Additionally we investigate the effect of the Polyakov loop on the chiral phase transition, finding that magnetic catalysis at low µ B is present, but weakened by the Polyakov loop.