Precision $YN$ and $\bar{n}N$ measurements with an LH$_2$/LD$_2$ target in the BESIII detector

TL;DR

The paper proposes installing a liquid hydrogen/deuterium target in BESIII to significantly improve the precision of hyperon-nucleon and antineutron-nucleon interaction measurements, advancing understanding of strong interactions.

Contribution

It introduces a dedicated target upgrade at BESIII, validated by simulations, to enhance effective luminosity and measurement precision for baryon interactions.

Findings

Simulations show negligible impact on charged particle tracking.

Effective luminosity for scattering on free protons increases by a factor of 10–30.

The upgrade enables high-precision measurements of $YN$ and $ar{n}N$ interactions.

Abstract

Located at the BEPCII $e^{+}e^{-}$ collider, the BESIII experiment provides a robust platform for investigating (anti)hyperon-nucleon ($YN$) and antineutron-nucleon ($\bar{n}N$) interactions. This is made possible by the high production cross-sections of $J/\psi$ and $\psi(3686)$ resonances and their substantial decay branches into these baryons. Although previous studies using the beam pipe as a target demonstrated feasibility, statistical precision remains constrained by the limited material budget. To address this, we propose installing a dedicated liquid hydrogen or liquid deuterium target between the beam pipe and the Cylindrical Gas Electron Multiplier Inner Tracker. Monte Carlo simulations confirm that the added material has a negligible effect on charged particle tracking. This upgrade is expected to enhance the effective luminosity for scattering on free protons by a factor of 10--30 for $\Lambda$, $\Sigma^{+}$, $\Xi$, and $\bar{n}$ beams, enabling high-precision measurements of $YN$ and $\bar{n}N$ interactions that will significantly advance our knowledge of non-perturbative strong interactions.