Could SBND-PRISM probe Lepton Flavor Violation?

TL;DR

This paper explores how the SBND-PRISM setup at Fermilab can significantly improve constraints on lepton flavor violating decays of pions and kaons, using neutrino beam angular spread to reduce uncertainties.

Contribution

It demonstrates the potential of SBND-PRISM to set new, more stringent limits on lepton flavor and number violating decays, enhancing previous experimental bounds.

Findings

SBND-PRISM can improve limits on $ m{BR}( ext{pions/kaons} o ext{lepton flavor violation})$ by factors of 9 and 1.25.

The setup can also probe lepton number violating decays, though less stringently than past experiments.

Several strategies for the SBND collaboration to further enhance this analysis are proposed.

Abstract

We investigate the possibility of using the Short-Baseline Near Detector (SBND) at Fermilab to constrain lepton flavor violating decays of pions and kaons. We study how to leverage SBND-PRISM, the use of the neutrino beam angular spread to mitigate systematic uncertainties, to enhance this analysis. We show that SBND-PRISM can put stringent limits on the flavor violating branching ratios $\rm{BR}(\pi^+ \to \mu^+ \nu_e) = 8.9 \times 10^{-4}$, $\rm{BR}(K^+ \to \mu^+ \nu_e) = 3.2 \times 10^{-3}$, improving previous constraints by factors 9 and 1.25, respectively. We also estimate the SBND-PRISM sensitivity to lepton number violating decays, $\rm{BR}(\pi^+ \to \mu^+ \overline{\nu}_e)= 2.1 \times 10^{-3}$ and $\rm{BR}(K^+ \to \mu^+ \overline{\nu}_e) = 7.4 \times 10^{-3}$, though not reaching previous BEBC limits. Last, we identify several ways how the SBND collaboration could improve this analysis.