Skyrmions and the pion mass

We present numerical evidence that suggests the introduction of a nonzero pion mass might dramatically affect the structure of minimal energy skyrmions. It appears that the shell-like skyrmions which are the minima when the pions are massless can fail to be minimal energy bound states for particular baryon numbers, with a strong dependence upon the value of the pion mass. The effects of a pion mass may include the replacement of shell-like configurations with crystal chunks and the loss of shell-like bound states with baryon numbers five and eight; which is in agreement with expectations based on real nuclei. (C) 2004 Elsevier B.V. All rights reserved.