Searching for apparent baryon number violation in $\Lambda_c^+$ decays at the Super Tau-Charm Facility

TL;DR

This paper proposes searches for apparent baryon number violation in charm-baryon decays at the Super Tau-Charm Facility, evaluating sensitivities and interpreting results within new physics frameworks.

Contribution

It introduces novel experimental channels for BNV in charm decays and assesses their potential to probe new physics scales at STCF.

Findings

STCF can probe new physics scales of several TeV in the sterile neutrino framework.

Projected sensitivities can constrain RPV SUSY parameters to about 0.1 TeV^{-2}.

The proposed searches are highly competitive for exploring BNV interactions in charm decays.

Abstract

Observation of baryon number violation (BNV) in laboratory experiments would constitute unambiguous evidence for physics beyond the Standard Model. We propose dedicated searches for \textit{apparent} BNV in charm-baryon decays, $\Lambda_c^+\to M^+ +$ missing energy ($M=\pi, K$) where the missing energy stems from a resonance. These channels have not been explored experimentally so far, despite the relatively clean environment potentially provided by near $\Lambda_c^+\overline{\Lambda}_c^-$ threshold production at $e^+e^-$ colliders. Performing state-of-the-art Monte Carlo simulations for the proposed Super Tau-Charm Facility (STCF), we evaluate the signal efficiencies and derive projected model-independent sensitivities under the assumption of negligible background. We further interpret these sensitivities within two theoretical frameworks: a sterile-neutrino-extended low-energy effective field theory ($\nu$LEFT) and R-parity-violating (RPV) supersymmetry. With an integrated luminosity of 1 ab$^{-1}$, STCF can probe new-physics scales of several TeV in the $\nu$LEFT description and constrain the RPV model parameter $\lambda''_{212}/m^2_{\tilde{q}}$ down to about $0.1~\mathrm{TeV}^{-2}$. Our results demonstrate that STCF provides a highly competitive opportunity for probing BNV interactions in rare charm-baryon decays.