Classical Nambu-Goldstone fields

TL;DR

This paper explores how Nambu-Goldstone bosons, like majorons, can be produced coherently in particle systems with changing quantum numbers, potentially affecting neutrino oscillations in astrophysical environments.

Contribution

It demonstrates that NG fields can be generated by large particle ensembles despite weak coupling, especially during flavor oscillations with net quantum number changes.

Findings

NG bosons can be coherently produced without direct coupling.

Classical NG fields may influence neutrino oscillations in stars.

Neutrino-majoron coupling limits can be improved to $m_{\nu}/300$ GeV.

Abstract

It is shown that a Nambu-Goldstone (NG) field may be coherently produced by a large number of particles in spite of the fact that the NG bosons do not couple to flavor conserving scalar densities like $\bar{\psi}\psi$. If a flavor oscillation process takes place the phases of the pseudo-scalar or flavor violating densities of different particles do not necessarily cancel each other. The NG boson gets a macroscopic source whenever the total (spontaneously broken) quantum number carried by the source particles suffers a net increase or decrease in time. If the lepton numbers are spontaneously broken such classical NG (majoron) fields may significantly change the neutrino oscillation processes in stars pushing the observational capabilities of neutrino-majoron couplings down to $m_{\nu}/300$ GeV.