Constraint on solar axions from seismic solar models

We reexamine the theoretical limit on the axion coupling to two photons, $g_{a\gamma \gamma }$, in the light of a new solar model (seismic solar model) and the latest solar neutrino observations, the Super-Kamiokande and the Sudbury Neutrino Observatory (SNO). From the comparison of the theoretically expected and the measured neutrino fluxes, we set a limit $g_{a\gamma \gamma} < 4.0\times 10^{-10} ~$\mathrm{G}\mathrm{e}\mathrm{V}$ ^{-1}$. This limit based on a new procedure is about a factor of 3 improvement over the previous theoretical limit and a more severe limit than the solar axion experiments. Therefore this limit is the most stringent limit on solar axions.