Constraints on flavor-dependent long range forces from solar neutrinos and KamLAND

Abstract

Flavor-dependent long range (LR) leptonic forces, like those mediated by the $L_e-L_\mu$ or $L_e -L_\tau$ gauge bosons, constitute a minimal extension of the standard model that preserves its renormalizability. We study the impact of such interactions on the solar neutrino oscillations when the interaction range $R_{LR}$ is much larger than the Earth-Sun distance. The LR potential can dominate over the standard charged current potential inside the Sun in spite of strong constraints on the coupling $\alpha$ of the LR force coming from the atmospheric neutrino data and laboratory search for new forces. We demonstrate that the solar and atmospheric neutrino mass scales do not get trivially decoupled even if $\theta_{13}$ is vanishingly small. In addition, for $\alpha \gsim 10^{-52}$ and normal hierarchy, resonant enhancement of $\theta_{13}$ results in nontrivial energy dependent effects on the $\nu_e$ survival probability. We perform a complete three generation analysis, and obtain constraints on $\alpha$ through a global fit to the solar neutrino and KamLAND data. We get the $3\sigma$ limits $\alpha_{e\mu} < 3.4 \times 10^{-53}$ and $\alpha_{e\tau} < 2.5 \times 10^{-53}$ when $R_{LR}$ is much smaller than our distance from the galactic center. With larger $R_{LR}$, the collective LR potential due to all the electrons in the galaxy becomes significant and the constraints on $\alpha$ become stronger by upto two orders of magnitude.