Measurement of electron-neutrino electron elastic scattering

Abstract

The cross section for the elastic scattering reaction ${\ensuremath{\nu}}_{e}{+e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e}{+e}^{\ensuremath{-}}$ was measured by the Liquid Scintillator Neutrino Detector using a ${\ensuremath{\mu}}^{+}$ decay-at-rest ${\ensuremath{\nu}}_{e}$ beam at the Los Alamos Neutron Science Center. The standard model of electroweak physics predicts a large destructive interference between the charge current and neutral current channels for this reaction. The measured cross section, ${\ensuremath{\sigma}}_{{\ensuremath{\nu}}_{e}{e}^{\ensuremath{-}}}=[10.1\ifmmode\pm\else\textpm\fi{}1.1(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{E}_{{\ensuremath{\nu}}_{e}}(\mathrm{MeV})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}45}{\mathrm{cm}}^{2},$ agrees well with standard model expectations. The measured value of the interference parameter, $I=\ensuremath{-}1.01\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{syst}),$ is in good agreement with the standard model expectation of ${I}^{\mathrm{SM}}=\ensuremath{-}1.09.$ Limits are placed on neutrino flavor-changing neutral currents. An upper limit on the muon-neutrino magnetic moment of $6.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}{\ensuremath{\mu}}_{\mathrm{Bohr}}$ is obtained using the ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ fluxes from ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\mu}}^{+}$ decay.