General gauge invariance and spin waves in theBphase of superfluidHe3

Abstract

Assuming that the $B$ phase of superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is described in terms of a spherical triplet state of Balian and Werthamer, the Goldstone bosons associated with the general gauge transformation of the $B$ phase are studied theoretically. Particular attention is paid to spin waves, which are the Goldstone bosons associated with (partially broken) gauge invariance of the original Hamiltonian against the rotation of the spin space. Spin-wave dispersions in the hydrodynamic regime of the $B$ phase are determined.