The all-flavor solar neutrino flux measured by the Sudbury Neutrino Observatory ( SNO ) constrains nonstandard energy losses to less than about 10 % of the Sun ’ s photon luminosity , superseding a helioseismological argument and providing new limits on the interaction strength of low-mass particles .
For the axion-photon coupling strength we find g _ { a \gamma } < 7 \times 10 ^ { -10 } ~ { } { GeV } ^ { -1 } .
We also derive explicit limits on the Yukawa coupling to electrons of pseudoscalar , scalar and vector bosons with keV-scale masses .