Effects of environment dependence of neutrino mass versus solar and reactor neutrino data

Abstract

In this work we study the phenomenological consequences of the environment dependence of neutrino mass on solar and reactor neutrino phenomenology. We concentrate on mass varying neutrino scenarios in which the enviroment dependence is induced by Yukawa interactions of a light neutral scalar particle which couples to neutrinos and matter. Under the assumption of one mass-scale dominance, we perform a global analysis of solar and KamLAND neutrino data which depends on 4 parameters: the two standard oscillation parameters, Δ m 2 0 , 21 and tan  2 θ 12 , and two new coefficients which parameterize the environment dependence of the neutrino mass. We find that, generically, the inclusion of the environment dependent terms does not lead to a very statistically significant improvement on the description of the data in the most favored MSW LMA (or LMA-I) region. It does, however, substantially improve the fit in the high- Δ m 2 LMA (or LMA-II) region which can be allowed at 98.9 % CL. Conversely, the analysis allow us to place stringent constraints on the size of the environment dependence terms which can be translated on a bound on the product of the effective neutrino-scalar ( λ ν ) and matter-scalar ( λ N ) Yukawa couplings, as a function of the scalar field mass ( m S ) in these models, | λ ν λ N | ( 10 − 7 eV m S ) 2 ≤ 3.0 × 10 − 28 (at 90 % CL) .