Red giant bound on the axion-electron coupling reexamined
Red giant bound on the axion-electron coupling reexamined
If axions or other low-mass pseudoscalars couple to electrons (``fine structure constant'' ${\mathrm{\ensuremath{\alpha}}}_{\mathit{a}}$) they are emitted from red giant stars by the Compton process \ensuremath{\gamma}+e\ensuremath{\rightarrow}e+a and by bremsstrahlung e+(Z,A)\ensuremath{\rightarrow}(Z,A)+e+a. We construct a simple analytic expression for the energy-loss rate for all conditions relevant for a red giant and include axion …