Quantum internal modes of solitons in 1d easy-plane antiferromagnet in strong magnetic field

In presence of a strong external magnetic field the dynamics of solitons in a one-dimensional easy-plane Heisenberg antiferromagnet exhibits a number of peculiarities. Dynamics of internal soliton degrees of freedom is essentially quantum, and they are strongly coupled to the "translational" mode of soliton movement. These peculiarities lead to considerable changes in the response functions of the system which can be detected experimentally.Comment: 8 pages, RevTeX, 6 figures, uses psfig.sty, submitted to PR