A Search for Sigma^0_5, N^0_5 and Theta^++ Pentaquark States

A high-resolution ({sigma}{sub instr.} = 1.5 MeV) search for narrow states ({Lambda} < 10 MeV) with masses of M{sub x} {approx} 1500-1850 MeV in ep {yields} e' K{sup +} X, e' K{sup -} X and e' {pi}{sup +} X electroproduction at small angles and low Q{sup 2} was performed. These states would be candidate partner states of the reported {Theta}{sup +}(1540) pentaquark. No statistically significant signal was observed in any of the channels at 90% C.L. Upper limits on forward production were determined to be between 0.7% and 4.2% of the {Lambda}(1520) production cross section, depending on the channel and the assumed mass and width of the state.