Search for Strange-Pentaquark Production in e+e- Annihilation at sqrt{s}=10.58 GeV and in Upsilon(4S) Decays

We search for strange pentaquark states that have been previously reported by other experiments --the {Theta}(1540){sup +}, {Xi}(1860){sup 2}, and {Xi}{sub 5}(1860){sup 0}--in 123 fb{sup -1} of data recorded with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. We find no evidence for these states and set 95% confidence level upper limits on the number of {Theta}(1540){sup +} and {Xi}{sub 5}(1860){sup 2} pentaquarks produced per e{sup +}e{sup -} annihilation into q{bar q} and per {Upsilon}(4S) decay. For q{bar q} events these limits are about eight and four times lower, respectively, than the rates measured for ordinary baryons of similar mass.