Beyond Tree Level with Solar Neutrinos: Towards Measuring the Flavor Composition and CP Violation

Abstract

After being produced as electron neutrinos ($\nu_e$), solar neutrinos partially change their flavor to $\nu_{\mu}$ and $\nu_{\tau}$ en route to Earth. Although the flavor ratio of the $\nu_e$ flux to the total flux has been well measured, the $\nu_{\mu}:\nu_{\tau}$ composition has not yet been experimentally probed. In this work we investigate the potential of the next-generation experiments for measuring the $\nu_{\mu}:\nu_{\tau}$ flavor ratio by utilizing flavor-dependent radiative corrections in the cross sections for $\nu_{\mu}$ and $\nu_{\tau}$ scattering. Since the transition probabilities of $\nu_e$ to $\nu_\mu$ and $\nu_\tau$ depend on the leptonic CP phase, we also investigate the sensitivity to the CP phase and show that a statistical significance of $\sim1 \sigma$ could be reached through precision measurements of solar neutrino spectra.