Strong supernovae bounds on ALPs from quantum loops

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 aγ (D) , differs significantly from the coupling appearing in the phenomenologically important Primakoff process, g aγ (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, ĝ 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 MeV < m a < 240 MeV. Moreover, we also show how cosmological bounds on the ALP-photon coupling translate into new, strong limits on ĝ 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.