Solitons with integer fermion number

Abstract

Necessary and sufficient conditions are found for any object in $3+1$ dimensions to have integer rather than fractional fermion number. Nontrivial examples include the Jackiw-Rebbi monopole and the already well studied Su-Schrieffer-Heeger soliton, both displaying integer multiples of elementary charges in combinations that normally are forbidden.

arXiv comment12 pages