Could SBND-PRISM probe Lepton Flavor Violation?

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 $\mathrm{BR}({\pi }^{+}\to {\mu }^{+}{\nu }_{\mathrm{e}})=8.9\times 10^{-4}$, $\mathrm{BR}({\mathrm{K}}^{+}\to {\mu }^{+}{\nu }_{\mathrm{e}})=3.2\times 10^{-3}$, improving previous constraints by factors 9 and 1.25, respectively. We also estimate the SBND-PRISM sensitivity to lepton number violating decays, $\mathrm{BR}({\pi }^{+}\to {\mu }^{+}{\overline{\nu }}_{\mathrm{e}})=2.1\times 10^{-3}$ and $\mathrm{BR}({\mathrm{K}}^{+}\to {\mu }^{+}{\overline{\nu }}_{\mathrm{e}})=7.4\times 10^{-3}$, though not reaching previous BEBC limits. Last, we identify several ways how the SBND collaboration could improve this analysis.

arXiv comment7 pages, 3 figures