Impact of the phase transition on Quark-Gluon Plasma with an extremely strong magnetic field in holographic QCD

Abstract: We investigate the phase transition within an extremely strong magnetic background field, employing a holographic Quantum Chromodynamics (QCD) model with a focus on entropy and pressure properties. At relatively modest magnetic field strengths, our study discerns a crossover transition between the normal phase and the Quark-Gluon Plasma (QGP) phase as the temperature rises. In contrast, under the influence of an extremely strong magnetic field, a first-order phase transition is observed. A critical point is identified at $ (eB_c, T_c) \approx (2.8623 \, \text{GeV}^2, 0.1191 \, \text{GeV}) $, which corresponds to a second-order phase transition. This phase structure is found to be in qualitative agreement with lattice simulation predictions reported in [Phys. Rev. D \textbf{105}, 034511 (2022)]. Furthermore, we explore the impact of the magnetic field on the jet quenching parameter across various phases. At zero magnetic field ($ eB = 0$ ), the normalized jet quenching parameter $ \hat{q} / T^3 $ exhibits a monotonic increase with temperature. However, in the presence of a magnetic background field, the normalized jet quenching parameters not only display directional anisotropy but also experience a universal enhancement, particularly in the vicinity of the critical temperature region. This observation suggests that the jet quenching parameter could potentially act as an indicator of phase transitions.