Pentaquark Searches in H1

TL;DR

This paper reports on searches for narrow baryonic states, including pentaquarks, in deep inelastic ep scattering, finding no evidence for new states but setting upper limits on their production relative to known baryons.

Contribution

The study provides the first mass-dependent upper limits on pentaquark production ratios in ep scattering at H1 energies, with no observed signals for hypothesized states.

Findings

No new narrow baryonic states observed in the specified mass ranges.

Mass-dependent upper limits set on pentaquark production ratios.

Observation of the standard baryon $ ext{Xi}(1530)^0$ in decay mode $ ext{Xi}^- ext{pi}^+$.

Abstract

We report on searches in deep inelastic $ep$ scattering for narrow baryonic states decaying into $\Xi^-\pi^-, \Xi^-\pi^+, \KS p$ and their charge conjugates, at centre-of-mass energies of 300 and 318 GeV. No signal for a new narrow baryonic state is observed in the mass ranges 1600-2100 MeV ($\Xi\pi$) and from threshold up to 1700 MeV ($\KS p$). The standard baryon $\Xi(1530)^0$ is observed in the decay mode $\Xi^-\pi^+$, and mass dependent upper limits on the ratio of the hypothetical pentaquark states $\Xi^{--}_{5q}$ and $\Xi^0_{5q}$ to the $\Xi(1530)^0$ signal are given. Also for the hypothetical strange pentaquark $\Theta^+$ mass dependent upper limits on $\sigma(ep\to e\Theta^+X)\times BR(\Theta^+\to K^0p)$ are obtained. Finally measurements of the acceptance corrected ratios $\sigma(D^{\ast}p(3100))/\sigma(D^{\ast})$ for the electroproduction of the anti-charmed baryon state $D^{\ast}p(3100)$ decaying into $D^{\ast}$ and $p$ are presented.