Search for a narrow baryonic state decaying to ${pK^0_S}$ and ${\bar{p}K^0_S}$ in deep inelastic scattering at HERA

TL;DR

This study searched for a narrow baryonic state decaying into pK^0_S and p̄K^0_S in deep inelastic scattering at HERA but found no evidence of such a resonance, setting upper limits on its production cross section.

Contribution

The paper provides a new, more extensive search for a baryonic state previously suggested, using a larger data set and different kinematic conditions, and reports null results.

Findings

No resonance peak observed in the 1.45-1.7 GeV mass range.

Upper limits established on the production cross section of the hypothetical state.

Contradicts earlier evidence of a state around 1.52 GeV.

Abstract

A search for a narrow baryonic state in the $pK^0_S$ and $\bar{p}K^0_S$ system has been performed in $ep$ collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb$^{-1}$ taken in 2003-2007. The search was performed with deep inelastic scattering events at an $ep$ centre-of-mass energy of 318 GeV for exchanged photon virtuality, $Q^2$, between 20 and 100 $\rm{} GeV^{2}$. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb$^{-1}$ taken in 1996-2000, no resonance peak was found in the $p(\bar{p})K^0_S$ invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.