Evidence for a narrow baryonic state decaying to K0(S) p and K0(S) anti-p in deep inelastic scattering at HERA
Journal
Physics Letters
Journal Volume
B591
Pages
7-22
Date Issued
2004
Author(s)
Abstract
A resonance search has been made in the K0Sp and K0Sp? invariant-mass spectrum 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�V318 GeV for exchanged photon virtuality, Q2, above 1 GeV2. Recent results from fixed-target experiments give evidence for a narrow baryon resonance decaying to K+n and K0Sp, interpreted as a pentaquark. The results presented here support the existence of such state, with a mass of 1521.5��1.5(stat.)+2.8?1.7(syst.) MeV and a Gaussian width consistent with the experimental resolution of 2 MeV. The signal is visible at high Q2 and, for Q2>20 GeV2, contains 221��48 events. The probability of a similar signal anywhere in the range 1500�V1560 MeV arising from fluctuations of the background is below 6��10?5.
SDGs
Type
journal article