Pentaquark Searches in H1

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.