A High Statistics Search for Electron-Neutrino --> Tau-Neutrino Oscillations

TL;DR

This paper reports new experimental limits on electron neutrino to tau neutrino and sterile neutrino oscillations, improving sensitivity in high-energy neutrino beam experiments and setting the most stringent upper limits to date.

Contribution

It provides the first high-statistics search for nu_e to nu_tau oscillations using a wide-band neutrino beam, establishing new upper limits on oscillation parameters.

Findings

Established the lowest 90% confidence upper limit on sin^2(2α) of 9.9 x 10^(-2) at delta-m^2 of 125 eV^2.

Improved sensitivity over previous experiments in high-energy neutrino oscillation searches.

Utilized electromagnetic decay modes of tau for electron neutrino appearance detection.

Abstract

We present new limits on nu_e to nu_tau and nu_e to nu_sterile oscillations by searching for electron neutrino dissappearance in the high-energy wide-band CCFR neutrino beam. Sensitivity to nu_tau appearance comes from tau decay modes in which a large fraction of the energy deposited is electromagnetic. The beam is composed primarily of muon neutrinos but this analysis uses the 2.3% electron neutrino component of the beam. Electron neutrino energies range from 30 to 600 GeV and flight lengths vary from 0.9 to 1.4 km. This limit improves the sensitivity of existing limits and obtains a lowest 90% confidence upper limit in sin**2(2*alpha) of 9.9 x 10**(-2) at delta-m**2 of 125 eV**2.