Spin polarized phases in strongly interacting matter: Interplay between axial-vector and tensor mean fields

Abstract

The spontaneous spin polarization of strongly interacting matter due to axial-vector-and tensor-type interactions is studied at zero temperature and high baryon-number densities. We start with the mean-field Lagrangian for the axial-vector and tensor interaction channels and find in the chiral limit that the spin polarization due to the tensor mean field (U) takes place first as the density increases for sufficiently strong coupling constants, and then the spin polarization due to the axial-vector mean field (A) emerges in the region of the finite tensor mean field. This can be understood as making the axial-vector mean-field finite requires a broken chiral symmetry somehow, which is achieved by the finite tensor mean field in the present case. It is also found from the symmetry argument that there appear the type I (II) Nambu-Goldstone modes with a linear (quadratic) dispersion in the spin polarized phase with U ≠ 0 and A ¼ 0 (U ≠ 0 and A ≠ 0), although these two phases exhibit the same symmetry breaking pattern.

Dimensional reduction and the generalized pion in a magnetic field within the NJL model

“…As we mentioned before, a non-trivial coupling constant κ of the anomalous magnetic moment is produced through several microscopic mechanisms. The coefficient of quark AMM is not uniquely adopted in many previous works [32][33][34][35][36][37][38][39][40], which is proportional to either q f , or q 2 f , or charge independent if it is created via a compensation of the color-AMM. The main point in the present investigation is that we will dynamically determine and extract it from the gap equations in the following.…”

“…Indeed, the eB-field is not the only source responding to the spin-dependent anomaly but also several microscopic mechanisms offer a momentum-dependent AMM for strongly interacting fermions [26][27][28][29][30][31]. The effects of quark AMM on the phase structure as well as mesonic properties are found in the works of [32][33][34][35][36][37][38][39][40].…”

Hybrid stars from the NJL model with a tensor interaction

“…In Ref. [30], a relation ρu = ρd is used. However, in our case, this condition is not satisfied because we are imposing the β equilibrium and the charge neutrality conditions on the system.…”

Non-zero tensor condensates in cold quark matter within the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction

“…1) As is indicated by many authors, there may exist various phases such as the color superconducting phase, 2)-4) the quarkyonic phase, 5) the inhomogeneous chiral condensed phase, 6) the quark ferromagnetic phase, 7) the color-ferromagnetic phase, 8) the spin polarized phase due to the axial vector interaction 9)- 12) or due to the tensor interaction. 13)- 23) In order to investigate the phase structure in quark matter at finite baryon density, various effective models of QCD are used because in the region of large quark chemical potential, the numerical simulation by using the lattice QCD did not work until now. One of the effective models of QCD, the Nambu-Jona-Lasinio (NJL) model 24) is widely used 25), 26) because it contains chiral symmetry, an important QCD symmetry.…”