Probing nonstandard neutrino-electron interactions with solar and reactor neutrinos

Most neutrino mass extensions of the standard electroweak model entail nonstandard interactions which, in the low-energy limit, can be parametrized in term of effective four-fermion operators ν_αν_βf̄f. Typically of subweak strength ϵ_αβGF, these are characterized by dimensionless coupling parameters ϵ_αβ, which may be relatively sizable in a wide class of schemes. Here we focus on nonuniversal flavor-conserving couplings (α=β) with electrons ($f=e$) and analyze their impact on the phenomenology of solar neutrinos. We consistently take into account their effect both at the level of propagation, where they modify the standard Mikheev-Smirnov-Wolfenstein behavior, and at the level of detection, where they affect the cross section of neutrino elastic scattering on electrons. We find limits which are comparable to other existing model-independent constraints.