Axions, Monopoles and Cosmic String

Abstract

We are discussing some aspects of the magnetic monopoles and cosmic strings interactions with axion domain walss and membranes. The monopole moving through an axion domain wall is transformed into a monopole bag - the state with a dyon quantum number, but smaller mass. In the case of an axion membrane the passing monopole excites the chiral charged state at the membrane boundary. It will be shown that if cosmic string intersects an axion domain wall there will be $\theta = \pi$, i.e. maximal $CP$-violation inside the string. Strings carrying the flux of the $Z$-boson field become the sources of the baryon charge nonconservation. The symbiosis of the two pictures - monopole passing through an axion domain wall and string intersecting it - is the case of the interaction between an axion domain wall and a Nambu electroweak string carrying $SU(2)_{L}$ monopoles at the ends.