Search for a narrow baryonic state decaying to $pK^S_0$ and $\bar{p}K^S_0$ in deep inelastic scattering with the HERA II data

TL;DR

This study searched for a narrow strange baryonic state decaying into $pK^0_S$ or $ar{p}K^0_S$ in deep inelastic scattering data from HERA II, finding no evidence and setting upper limits on production cross sections.

Contribution

The paper improves previous searches by using larger statistics and enhanced particle identification in HERA II data to look for exotic baryonic states.

Findings

No evidence for the narrow baryonic state at 1.52 GeV.

Upper limits on production cross section are established.

Analysis benefits from improved particle ID and larger dataset.

Abstract

This paper presents the result of a search for a narrow strange baryonic state in the invariant-mass distribution of $pK^0_S(\overline{p}K^0_S)$ in HERA II data (2003-2007). The search was performed in the deep inelastic scattering (DIS) data with photon virtuality, $Q^2$, between 20 and 100 GeV. The analysis in HERA II period has improvements over the previous ZEUS analysis in HERA I period (1996-2000). These consist of large statistics and improved particle identification performance by using both of the CTD $dE/dx$ and the MVD $dE/dx$ in this search. Contrary to evidence for such an exotic state around 1.52 GeV in the HERA I data, no such state is found in this analysis. The upper limits on the production cross section are set at 95% confidence level.