The Axion-Photon Coupling in Two Benchmark Models Against the CAST Bound, Read in a Bounced Cosmology

At a decay constant of 10^10 GeV the KSVZ coupling is 2.23e-13 per GeV and the DFSZ coupling is 8.67e-14 per GeV; the DFSZ value is a factor of 3.89e-01 of the KSVZ value, entirely because of the E/N term. Setting each coupling equal to the CAST value of 6.60e-11 per GeV gives minimum decay constants of 3.38e+07 GeV for KSVZ and 1.31e+07 GeV for DFSZ. The DFSZ benchmark, whose coupling partially cancels, tolerates a decay constant about two and a half times smaller. Neither number involves the bounce density of 9.72e+54 g per cubic centimetre in any way: no step of the solar calculation samples densities or temperatures within many orders of magnitude of the bound. This study is computed from stated assumptions and published comparison values; it is not a measurement.