Enhancement of Weak Interactions in Phase Transitions in Condensed Matter and Early Universe

Abstract

Parity-violating weak interactions produce extremely small energy differences between left- and right-handed chiral systems. We show that these microscopic effects may be strongly amplified during collective phenomena such as phase transitions. The enhancement factor is proportional to the critical number of atoms, $N_c$, in the nucleus of the new phase. After the nucleus reaches its critical size, it grows until it fills the entire system. Measurement of the ratio of produced left and right chiral structures may provide a way to measure this critical number $N_c$. Experiments where definite spin-chiral structures are formed during a phase transition in crossed electric and magnetic fields, indicate $N_c\sim 10^9-10^{10}$. An open question is whether a similar enhancement could operate during cosmological phase transitions - thereby boosting CP-violating effects sufficiently to contribute to the observed baryon-to-photon ratio.