Search for the Theta+ Pentaquark in the gammad--> DeltanK+ reaction measured with the CLAS spectrometer

Phys Rev Lett. 2006 Jul 21;97(3):032001. doi: 10.1103/PhysRevLett.97.032001. Epub 2006 Jul 17.


For the first time, the reaction gammad-->DeltanK+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Laboratory, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant-mass distribution. The upper limit on the gammad-->DeltaTheta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.