Search for Pentaquark partners in Jefferson Lab Hall A
Yi Qiang
MIT

Recent observations of a narrow, exotic baryonic state now known as the $\Theta^+$, have generated great experimental and theoretical interests. If confirmed, the the $\Theta^+$ could be a 5-quark state which has been predicted to be a member of an antidecuplet of the flavor group $SU(3)_F$. The other members of this antidecuplet should also be observable if they are sufficiently narrow. A high-resolution, high-statistics search for narrow resonances in the missing mass spectra of $H(e,e^\prime K^-)X$ and $H(e,e^\prime K^+)X$ has be performed by Jefferson Laboratory experiment 04-012. The focus of the experiment is to search the $\Sigma^0$ and $\Theta^{++}$ partners of the $\Theta^+$ pentaquark. The experiment finished running in early June using the two Hall A HRS spectrometers. After introduced a new cerenkov PID detector, RICH, the performance for separating kaon from pion has been greatly improved. With a resolution (FWHM) of 3.0 MeV, data covering the range in missing mass of 1560-1860 MeV for the $\Sigma^0$ and 1450-1620 MeV for the $\Theta^{++}$ have been collected. Some preliminary results from this experiment will be presented.