Detecting light leptophilic gauge boson at BESIII detector

TL;DR

This paper investigates the potential to detect a light leptophilic U-boson, proposed to mediate lepton and dark matter interactions, at the BESIII experiment through specific decay channels, assessing sensitivity to its coupling strength.

Contribution

It provides the first detailed analysis of BESIII's sensitivity to a light U-boson in both visible and invisible decay channels, considering realistic backgrounds and coupling limits.

Findings

BESIII can measure U-boson coupling down to 10^{-4} - 10^{-5} in invisible decay channels.

BESIII can measure U-boson coupling down to 10^{-3} - 10^{-4} in visible decay channels.

The study demonstrates BESIII's potential to probe leptophilic gauge bosons relevant for dark matter models.

Abstract

The $ O(GeV)$ extra $ U(1)$ gauge boson named U-boson, has been proposed to mediate the interaction among leptons and dark matter (DM), in order to account for the observations by PAMELA and ATIC. In such kind of models, the extra U(1) gauge group can be chosen as $U(1)_{L_i-L_j}$ with $L_i$ the $i-$th generation lepton number. This anomaly-free model provides appropriate dark matter relic density and boost factor required by experiments. In this work the observability of such kind of U-boson at BESIII detector is investigated through the processes $ e^ + e^ - \to U\gamma$, followed by $U\to e^+e^-$, $U\to \mu^+\mu^-$ and $U\to \nu\overline{\nu}$. In the invisible channel where U-boson decays into neutrinos, BESIII can measure the coupling of the extra $ U(1)$ down to $ O(10^{- 4}) \sim O(10^{- 5})$ because of the low Standard Model backgrounds. In the visible channel where U-boson decays into charged lepton pair, BESIII can only measure the coupling down to $ O(10^{- 3}) \sim O(10^{- 4})$ due to the large irreducible QED backgrounds.