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 $\sim 1\sigma$ could be reached through precision measurements of solar neutrino spectra.

Comments: 6 pages, 5 figures