QCD phase diagram with a background magnetic field in an improved soft-wall AdS/QCD model

We studied the magnetic effects on the chiral transition and the melting properties of vector and axial-vector mesons in the improved soft-wall AdS/QCD model under a charged magnetic background, which is solved perturbatively from an Einstein–Maxwell system with a negative cosmological constant. The phase diagrams for both chiral transition and meson melting have been obtained. We show that the inverse magnetic catalysis emerged naturally in the improved soft-wall model. We also find that the magnetic field can induce meson melting, at least for the vector and axial-vector mesons, in our holographic setup.

Thermodynamics of soft wall model of AdS/QCD in Einstein-Maxwell-Gauss-Bonnet Gravity

We investigate the thermodynamics of confinement/deconfinement transition in soft wall model of QCD with Gauss-Bonnet corrections using AdS/CFT correspondence. In bulk AdS space-time the transition is geometric and is known as Hawking-Page transition. The Hawking-Page transition between two geometries, namely charged AdS black hole and thermally charged AdS have been studied with Gauss-Bonnet corrections up-to first order. The Gauss-Bonnet coupling modifies the transition temperature of the system, but qualitative features remain unchanged. We obtain the curves between chemical potential and transition temperature for different values of Gauss-Bonnet couplings. We find that there exist a point in μ-T plane where lines with different value of Gauss-Bonnet coupling cross each other. This point may be the onset of the transition from first order to cross over behavior. The results are compared with that of the hard wall model.