Bounds on the Coupling of the Majoron to Light Neutrinos from Supernova Cooling

Abstract

We explore the role of Majoron ($J$) emission in the supernova cooling process, as a source of upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to $ν_e$ comes from the $ν_eν_e \to J $ process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to $ν_{μ(τ)}ν_{μ(τ)}$ and on off-diagonal $ν_e ν_{μ(τ)}$ couplings in various regions of the parameter space. We discuss the evaluation of the cross-section for four-particle interactions ($νν\to JJ$ and $νJ \to νJ$). We show that these are typically dominated by three-particle sub-processes and do not give new independent constraints.