Limits on the Non-Standard Interactions of Neutrinos from $e^{+}{e}^{-}$ Colliders

Abstract

We provide an effective Lagrangian analysis of contact non-standard interactions of neutrinos with electrons, which can be effectively mediated by extra particles, and examine the associated experimental limits. At present, such interactions are strongly constrained only for ${\nu }_{\mu }$: the bounds are loose for ${\nu }_e$ and absent for ${\nu }_{\tau }$. We emphasize the unique role played by the reaction $e^{+}{e}^{-}\to \nu \bar{\nu }\gamma$ in providing direct constraints on such non-standard interactions.

Comments: 15 LaTeX pages, 6 postscript figures, uses epsfig. New discussion on bounds from reactor anti-neutrino scattering off electrons; minor changes. To appear on Phys. Lett. B