Goldstone bosons versus domain walls bounded by cosmic strings

Abstract

It is shown that two possible schemes of string bounded domain wall formation are closely related. Walls can be avoided if a certain type of couplings between scalars, responsible for string and wall formation, is excluded from the potential. This enlarges the continous global symmetry of the model which, being broken, instead of domain walls gives rise to global strings and Gold-stone bosons. A realistic example of spontaneously broken family symmetry is considered. It is shown that the existence of the axion in the model with local chiral flavour symmetry SU(3)H can solve the domain wall problem.