Muons in Supernovae: Implications for the Axion-Muon Coupling

Abstract

The high temperature and electron degeneracy attained during a supernova allow for the formation of a large muon abundance within the core of the resulting protoneutron star. If new pseudoscalar degrees of freedom have large couplings to the muon, they can be produced by this muon abundance and contribute to the cooling of the star. By generating the largest collection of supernova simulations with muons to date, we show that observations of the cooling rate of SN 1987A place strong constraints on the coupling of axionlike particles to muons, limiting the coupling to g aμ < 10 −8.1 GeV −1 .

Looking forward to lepton-flavor-violating ALPs

“…Note that this rather crude treatment of the PNS's thermodynamics appears to be consistent with the results from the dedicated simulations in ref. [45], since we obtain similar bounds on F A µµ using the expressions for the energy loss rate through Compton (as appropriate for muons) with the above input.…”

“…We have also included the recent bounds on ALP couplings to muons obtained in ref. [45] from SN1987A (see also ref. [46]).…”

Global fits of axion-like particles to XENON1T and astrophysical data

“…In fact, the authors of ref [105]. challenge the validity of the bound itself by appealing to an alternative model for the delayed neutrino burst; see ref [106]. for further discussion.…”

Ultralight scalars in leptonic observables

“…Plenty of works have recently studied the question of cooling by the emission of ultralight scalars in astrophysical scenarios [11,39,[43][44][45]. However, to the best of our knowledge, all of them consider axions or ALPs.…”

“…The coupling with muons has been recently studied in some works [39,43,44]. In this case the process ultimately used to set the contraint is neutrino production, clearly suppressed if energy is transported out of the supernova by scalars produced in µ + γ → µ + φ.…”