$L_{\mu }-L_{\tau }$ gauge bosons in beam dumps and supernovae

Abstract

We study the phenomenology of a sub-GeV $L_{\mu }-L_{\tau }$ gauge boson. We find discrepancies with existing literature in sensitivity projections for the upcoming SHiP experiment and in the treatment of supernovae cooling constraints. We present a quantitative analysis of different production modes in beam dumps and compare our results to previous work. In the context of supernovae, we re-evaluate the standard supernova cooling bounds from SN1987A and analyze additional supernova-based probes: diffusive cooling, constraints from the existence of low-energy supernovae, and the absence of a high-energy neutrino signal from SN1987A.

Comments: 34 pages, 9 figures