Solar neutrino limit on axions and keV-mass bosons

TL;DR

This paper uses the SNO measurement of the all-flavor solar neutrino flux to bound nonstandard energy losses in the Sun, focusing on axions and keV-scale bosons. It employs self-consistent solar models including axion emission via the Primakoff process to relate the neutrino flux to the axion luminosity, yielding a robust bound on the axion-photon coupling $g_agamma < 7\times10^{-10}$ GeV$^{-1}$, which improves upon helioseismology limits and is competitive with CAST in the sub-eV mass range. The authors also compute the Compton production of keV-mass bosons coupled to electrons and derive explicit limits on $g_{ee\chi}$ for pseudoscalar, scalar, and vector cases, with detailed cross-sections provided. Overall, the work provides a direct solar interior constraint on light bosons, informs solar axion searches, and clarifies the viability of keV-scale bosons as dark matter candidates by comparing with laboratory bounds and correcting prior axio-electric rate estimates that affected DAMA interpretations.

Abstract

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_aγ< 7E-10 1/GeV. We also derive explicit limits on the Yukawa coupling to electrons of pseudoscalar, scalar and vector bosons with keV-scale masses.

Figures (1)

• Figure 1: Mass dependence of the solar $g_{ee\chi}$ limit. The PS curve supersedes the one in our original preprint that was reproduced in Ref. Aalseth:2008rx.