Search for the Lepton Number Violating Process nu_mu-bar e^- -> mu^- nu_e-bar

TL;DR

The NuTeV experiment searched for lepton number violation in neutrino-electron interactions, found no evidence, and set strict upper limits on the process's cross-section ratio, confirming the Standard Model predictions.

Contribution

First experimental search for lepton number violation in nu_mu-bar e^- interactions with the most restrictive limits to date.

Findings

No evidence for lepton number violation was observed.

Measured inverse muon decay cross-section consistent with Standard Model.

Set upper limits on LNV/IMD cross-section ratio at 90% confidence level.

Abstract

The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to perform a search for the lepton number violating process nu_mu-bar e^- -> mu^- nu_e-bar, and to measure the cross-section of the Standard Model inverse muon decay process nu_mu e^- -> mu^- nu_e. NuTeV measures the inverse muon decay asymptotic cross-section sigma/E to be 13.8 +/- 1.2 +/- 1.4 x 10^-42 cm^2/GeV. The experiment also observes no evidence for lepton number violation and places one of the most restrictive limits on the LNV/IMD cross-section ratio at < 1.7% at 90% C.L. for V-A couplings and < 0.6% for scalar couplings.