Detecting CNO solar neutrinos in next-generation xenon dark matter experiments

Abstract

We study the prospects for measuring the low-energy components of the solar neutrino flux in future direct dark matter detection experiments. We show that for a depletion of $^{136}$Xe by a factor of 100 relative to its natural abundance, and an extension to electron recoil energies of $\sim$ MeV, future xenon experiments with exposure $\sim 200$ ton-yr can detect the CNO component of the solar neutrino flux at $\sim 3 \sigma$ significance. A CNO detection will provide important insight into metallicity of the solar interior. Precise measurement of low-energy solar neutrinos, including as $pp$, $^7$Be, and $pep$ components, will further improve constraints on the "neutrino luminosity" of the Sun, thereby providing constraints on alternative sources of energy production. We find that a measurement of $L_{\nu}/L_{\odot}$ of order one percent is possible with the above exposure, improving on current bounds from a global analysis of solar neutrino data by a factor of about seven.