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(a gamma)((D)), differs significantly from the coupling appearing in the phenomenologically important Primakoff process, g(a gamma)((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, (g) over cap (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 (g) over cap (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.

Automated summary

We demonstrate that the one-loop effective coupling of axionlike particles (ALPs) to photons is process dependent in theories where they are coupled to electrons. This has significant implications for the physics of massive ALPs in hot and dense environments, such as supernovae.