Field Splitting of the New Sound Attenuation Peak inHe3-B

The recently observed new collective mode in the zero-sound propagation in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$ is shown experimentally to split linearly with magnetic field into five components and to display the characteristic angular dependence of a $J=2\mathrm{}$ multiplet. Agreement with the predicted splitting first computed by Tewordt and Schopohl leads to the identification of the newly found feature with the spin pair-vibration mode of the Balian-Werthamer state.