For the first time, the reaction gamma d ->Lambda nK(+) 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 gamma d ->Lambda Theta(+) 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.
S Niccolai, M Mirazita, P Rossi, NA Baltzell, et al.. "Search for the Theta(+) pentaquark in the gamma d ->Lambda nK(+) reaction measured with the CLAS spectrometer" Physical Review Letters
Vol. 97 Iss. 3 (2006)
Available at: http://works.bepress.com/michael_williams/9/