Observation of a narrow baryonic state in DIS at HERA

Abstract

A resonance search has been made in the K^{0}s-p, K^{0}s-pbar and K^{+}p invariant-mass spectra measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb^{-1}. The search was performed in the central rapidity region of inclusive deep inelastic scattering at an ep centre-of-mass energy of 300--318 GeV for exchanged photon virtuality, Q2, above 1 GeV^{2}. The results support the existence of a narrow state in K^{0}s-p and K^{0}s-pbar decay channels, consistent with the pentaquark prediction. No signal was found in the K^{+}p$ decay channel.