Strong supernovae bounds on ALPs from quantum loops

TL;DR

This paper derives new, strong bounds on ALP-electron couplings from supernova observations by accounting for quantum loop effects that alter effective photon couplings, impacting ALP phenomenology.

Contribution

It introduces process-dependent effective couplings for ALPs, derives novel supernova bounds considering loop effects, and clarifies the hierarchy constraints on ALP couplings due to quantum loops.

Findings

New limits on ALP-electron coupling from SN 1987A data.

Effective photon couplings are process-dependent due to quantum loops.

Large hierarchies in ALP couplings are unlikely once loops are included.

Abstract

We show that in theories of axionlike particles (ALPs) coupled to electrons at tree-level, the one-loop effective coupling to photons is process dependent: the effective coupling relevant for decay processes, $g_{a\gamma}^{\text{(D)}}$, differs significantly from the coupling appearing in the phenomenologically important Primakoff process, $g_{a\gamma}^{\text{(P)}}$. We show that this has important implications for the physics of massive ALPs in hot and dense environments, such as supernovae. We derive, as a consequence, new limits on the ALP-electron coupling, $\hat{g}_{ae}$, from SN 1987A by accounting for all relevant production processes, including one-loop processes, and considering bounds from excess cooling as well as the absence of an associated gamma-ray burst from ALP decays. Our limits are among the strongest to date for ALP masses in the range $0.03 \, \text{MeV} \, < m_a< 240 \, \text{MeV}$. Moreover, we also show how cosmological bounds on the ALP-photon coupling translate into new, strong limits on $\hat{g}_{ae}$ at one loop. Our analysis emphasises that large hierarchies between ALP effective couplings are difficult to realise once quantum loops are taken into account.