Strong supernovae bounds on ALPs from quantum loops

Understand

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 $0.03 \, \text{MeV} \, < m_a< 240 \, \text{MeV}$.