Contrasting solar and reactor neutrinos with a non-zero value of theta13

TL;DR

This paper investigates how a small, non-zero value of the neutrino mixing angle theta13 can reconcile differences in neutrino parameter estimates from separate solar and KamLAND data analyses, providing a combined best-fit value.

Contribution

It demonstrates that including a non-zero theta13 explains discrepancies between separate analyses and determines its best-fit value from combined data.

Findings

Best-fit sin^2 2 theta13 = 0.01 with uncertainties

Non-zero theta13 accounts for differences in parameter estimates

Joint analysis improves neutrino oscillation parameter constraints

Abstract

When solar neutrino and KamLAND data are analyzed separately one finds that, even though allowed regions of neutrino parameters overlap, the values of $\delta m^2$ and the mixing angle $\theta_{12}$ at the $\chi^2$ minima are different. We show that a non-zero, but small value of the angle $\theta_{13}$ can account for this behavior. From the joint analysis of solar neutrino and KamLAND data we find the best fit value of $\sin^2 2 \theta_{13} = 0.01 ^{-0.01}_{+0.09}$.