Spin polarizations under a pseudovector interaction between quarks with the Kobayashi–Maskawa–’t Hooft term in high density quark matter

Abstract

A possibility of a quark spin polarization originated from a pseudovector condensate is investigated in the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction which leads to flavor mixing. It is shown that a pseudovector condensate related to the strange quark easily occurs compared with pseudovector condensate related to light quarks. Further, it is shown that the pseudovector condensate related to the strange quark appears at a slightly small chemical potential by the effect of the flavor mixing due to the Kobayashi-Maskawa-'t Hooft interaction.

Hybrid stars from a three-flavor NJL model with two kinds of tensor condensates

“…If we include the pseudovector-type four-point interaction between quarks, the inner structure of compact star may change drastically. By our previous work [12,13], the pseudovector condensates appear at a lower quark chemical potential than that appearing the tensor condensates. Especially, the pseudovector condensates appear and vanish around the quark chemical potential where the chiral symmetry is restored.…”

“…However, in the region of low temperature and large quark chemical potential, the lattice simulation is still not working. In that region, it has been remarked that various phases [1] may appear such as the color superconducting phase [2][3][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][10][11][12][13] or due to the tensor interaction [14][15][16][17][18][19][20][21][22][23][24][25][26] and so on. The situation with large chemical potential and low temperature may be realized in the inner core of compact stars such as neutron stars and magnetars [27,28].…”

A possibility of existence of a pseudovector-type quark-antiquark condensate in the quark matter and Nambu-Goldstone modes on that condensate in the Nambu-Jona-Lasinio model

“…One of recent interests with respect to the strong interaction governed by the quantum chromodynamics (QCD) may be to clarify the phase structure on the plane spanned by the temperature and density [1]. Especially, at finite density and low temperature, some authors have pointed out [2][3][4][5] that there exists a possibility of a quark spin polarization due to a pseudovector-type quark-antiquark condensation by using the low energy effective model of QCD such as the Nambu-Jona-Lasinio (NJL) model. [6] Also, as was shown in the previous work, the spin polarization may also occur due to a tensor-type quark-antiquark condensate in the NJL model [7] and the magnetic moment density is evaluated in the hybrid star with a quark matter in the inner core of compact stars.…”

“…[12,13] In this paper, a possibility of the existence of the pseudovector-type quark-antiquark condensed phase in the quark matter is investigated and its possibility is indicated taking account of the vacuum effect that leads to the chiral symmetry breaking, which may be neglected in some previous investigations. [4,5] Further, the massless Nambu-Goldstone modes on the pseudovector condensate due to the psedovector interaction in the NJL model, which leads to the quark spin polarization, are investigated directly.…”