Interacting fermions in rotation: chiral symmetry restoration, moment of inertia and thermodynamics

Abstract

We study rotating fermionic matter at finite temperature in the framework of the Nambu-Jona-Lasinio model. In order to respect causality the rigidly rotating system must be bound by a cylindrical boundary with appropriate boundary conditions that confine the fermions inside the cylinder. We show the finite geometry with the MIT boundary conditions affects strongly the phase structure of the model leading to three distinct regions characterized by explicitly broken (gapped), partially restored (nearly gapless) and spontaneously broken (gapped) phases at, respectively, small, moderate and large radius of the cylinder. The presence of the boundary leads to specific steplike irregularities of the chiral condensate as functions of coupling constant, temperature and angular frequency. These steplike features have the same nature as the Shubnikov-de Haas oscillations with the crucial difference that they occur in the absence of both external magnetic field and Fermi surface. At finite temperature the rotation leads to restoration of spontaneously broken chiral symmetry while the vacuum at zero temperature is insensitive to rotation ("cold vacuum cannot rotate"). As the temperature increases the critical angular frequency decreases and the transition becomes softer. A phase diagram in angular frequency-temperature plane is presented. We also show that at fixed temperature the fermion matter in the chirally restored (gapless) phase has a higher moment of inertia compared to the one in the chirally broken (gapped) phase.

General equilibrium second-order hydrodynamic coefficients for free quantum fields

“…Another form of global equilibrium, which is a special case of eq. (2.6) is the pure rotation, with b = (1/T 0 , 0) and ̟ ∝ ω 0 /T 0 such that: 8) which has recently raised much attention for fermions [43,44]. In order to represent a physical fluid at equilibrium, β must be a timelike vector.…”

Feed-down effect on Λ spin polarization

“…Since the spin numbers for the weak decay 1/2 → 1/2 0 is the same as the strong decay above, the spin-density-matrix ρ D λ D ;λ D for this channel is also given by Eq. (19). The difference is that A ±1/2 is no longer constrained by Eq.…”

Nambu–Jona-Lasinio model in a sphere

“…We think the MIT boundary condition is more suitable for the finite size effects study in HICs than (anti)periodic boundary conditions for its confinement character. Note the authors of [41] already investigated the NJL model in a cylinder with the MIT boundary condition. Here we investigate the NJL model in a sphere with also the MIT boundary condition.…”