Magnetic moment of constituent fermions in ground states with spontaneously broken translational invariance

TY - JOUR

T1 - Magnetic moment of constituent fermions in ground states with spontaneously broken translational invariance

AU - Nielsen, Holger Frits Bech

AU - Soni, Vikram

PY - 2013/10/2

Y1 - 2013/10/2

N2 - Spontaneous symmetry breaking gives rise to a nonzero order parameter or a ground state expectation value (GEV) of the scalar field that generates energy gaps or constituent masses for the fermions via Yukawa interactions. There are several physical situations in which the order parameters or GEVs of the scalar field (and therefore constituent masses) can become space varying. This can change the definitions of several important physical operators. We investigate and rederive the generalized magnetic moment operator for 'constituent' fermions that arises from a space varying order parameter or GEV.We especially consider the high baryon density π0 condensed phase, in which chiral symmetry is spontaneously broken, with space varying expectation values of the σ and π0 fields. This phase has a spin polarized Fermi sea as the ground state. We show that there is indeed generated a macroscopic magnetization in this phase, contrary to what one would have found, if one just used a primitive phenomenological magnetic moment formula for explicit/current fermion masses. This is important in the context of neutron stars, as such a high density state may be responsible for very high magnetic fields in the dense core of neutron stars.

AB - Spontaneous symmetry breaking gives rise to a nonzero order parameter or a ground state expectation value (GEV) of the scalar field that generates energy gaps or constituent masses for the fermions via Yukawa interactions. There are several physical situations in which the order parameters or GEVs of the scalar field (and therefore constituent masses) can become space varying. This can change the definitions of several important physical operators. We investigate and rederive the generalized magnetic moment operator for 'constituent' fermions that arises from a space varying order parameter or GEV.We especially consider the high baryon density π0 condensed phase, in which chiral symmetry is spontaneously broken, with space varying expectation values of the σ and π0 fields. This phase has a spin polarized Fermi sea as the ground state. We show that there is indeed generated a macroscopic magnetization in this phase, contrary to what one would have found, if one just used a primitive phenomenological magnetic moment formula for explicit/current fermion masses. This is important in the context of neutron stars, as such a high density state may be responsible for very high magnetic fields in the dense core of neutron stars.

U2 - 10.1016/j.physletb.2013.08.046

DO - 10.1016/j.physletb.2013.08.046

M3 - Journal article

SN - 0370-2693

VL - 726

SP - 41

EP - 44

JO - Physics Letters B

JF - Physics Letters B

IS - 1-3

ER -