Comment on '"Pairing interaction and Galilei invariance"

A recent article by Dussel, Sofia, and Tonina studies the relation between Galilei invariance and dipole energy weighted sum rule(EWSR). The authors f ind that the pairing interaction, which is neither Galilei nor Lorentz inva riant, produces big changes in the EWSR and in effective masses of the nucl eons. They argue that these effects of the pairing force could be realistic . In this Comment we stress the validity of Galilei invariance to a very go od approximation in this context of low-energy nuclear physics and show tha t the effective masses and the observed change in the EWSR for the electric dipole operator relative to its classical value are compatible with this s ymmetry. [S0556-2813(99)00805-5].