Search for the baryon and lepton number violating decay $J/ψ\to pe^-$ + c.c

TL;DR

This work searches for baryon-number and lepton-number violating decays in $J/\psi$ using $(2712.4\pm14.3)\times 10^{6}$ $\psi(3686)$ events collected by BESIII. Employing a blind analysis of the channel $J/\psi\to p e^{-}$ via $\psi(3686)\to \pi^{+}\pi^{-}J/\psi$, no signal is observed and a stringent upper limit of $\mathcal{B}(J/\psi\to p e^{-})<3.1\times10^{-8}$ at 90% CL is set. This result constrains baryon- and lepton-number violating processes involving second-generation quarks and provides stronger constraints than prior BESIII searches, with significant improvements anticipated at future facilities such as a super $\tau$-charm factory. The analysis combines meticulous event selection, a 4C kinematic fit, and a rigorous treatment of systematic uncertainties, illustrating a robust framework for rare decay searches in charmonium systems.

Abstract

Based on $(2712.4\pm 14.3) \times 10^{6} $ ${ψ(3686)}$ events collected by the BESIII detector operating at the BEPCII storage ring, we perform a search for the baryon- and lepton-number violating decay $J/ψ\to pe^{-}+c.c.$ via $ψ(3686) \to π^{+}π^{-}J/ψ$. No significant signal is found. An upper limit on the branching fraction of $\mathcal{B}(J/ψ\to p e^{-}+ c.c.) < 3.1 \times 10^{-8}$ at 90\% confidence level.

Figures (1)

• Figure 1: The $M_{pe^{-}}$ distribution shows data points with error bars, the background as a green histogram, the signal MC as a blue histogram, and the signal region is marked by red dashed arrows.