Light mesons around critical end points in $T-μ_B-μ_I-eB$ space

Luyang Li; Shijun Mao

paper

Light mesons around critical end points in $T - μ_{B} - μ_{I} - e B$ space

arXiv:2107.10067

Abstract

Light mesons $(σ, π^{0}, π^{\pm})$ are investigated in $T - μ_{B} - μ_{I} - e B$ space by using a two-flavor NJL model, which are related to the chiral symmetry restoration and pion superfluid phase transition. In $T - μ_{B} - e B$ space, during the chiral restoration process, the mass of pseudo-Goldstone mode $π^{0}$ keeps increasing, together with the sudden mass jump. At the critical end point region, $π^{0}$ meson has a very sharp but continuous mass increase, together with a sudden mass jump at the Mott transition, and in the first order chiral phase transition region nearby, we observe twice $π^{0}$ mass jumps, induced by the Mott transition and quark mass jump, respectively. The mass of Higgs mode $σ$ first decreases and then increases associated with the chiral symmetry restoration, and shows a jump at the first order chiral phase transition. We plot the chiral phase diagram in terms of the change of quark mass, the Mott transition of $π^{0}$ and the minimum mass of $σ$ . Due to the explicit breaking of chiral symmetry in physical case, the chiral restoration phase boundaries in $T - μ_{B}$ plane from the order parameter and meson side are different from each other. In $T - μ_{I}$ plane, the competition between pion superfluid phase transition and chiral symmetry restoration under magnetic fields is studied in terms of the Goldstone mode $π^{+}$ and the pseudo-Goldstone mode $π^{0}$ . The separation of the two phase boundaries is enhanced by the external magnetic field. Different from the twice mass jumps of $π^{0}$ in the first order chiral phase transition region, the $π^{+}$ meson displays several mass jumps in the chiral crossover region. At the critical end point, $π^{+}$ also shows very sharp but continuous mass changes, together with a mass jump at the Mott transition.

arXiv comment20 pages, 4 figures

Light mesons around critical end points in T−μB​−μI​−eB space

Abstract

References in corpus (58)

Light mesons around critical end points in $T - μ_{B} - μ_{I} - e B$ space