Measurement of the Σπ photoproduction line shapes near the Λ(1405)

The CLAS Collaboration at Jefferson Lab measured the reaction gamma + p-->K+ + Sigma + pi over a broad range of photon energy and kaon production angles. The results summarized below are from the Ph.D. work of Kei Moriya, in collaboration with Professor Reinhard A. Schumacher, at Carnegie Mellon University in Pittsburgh, Pennsylvania. The thesis is entitled - Measurement of the Lineshape, Differential Photoproduction Cross Section, Spin and Parity of the Lambda(1405) Using CLAS at Jefferson Lab. The main body of the thesis describes the results given below, however, the numbers given here reflect an extra round of detailed checks and systematic studies summarized in a CLAS Analysis Note entitled - Addendum on Lambda(1405) Studies Using G11A, dated October 2, 2011. The thesis is available at www.jlab.org/Hall-B/general/clas_thesis.html. The analysis note is also somewhere on the CLAS web site. All known corrections were applied to the yield extraction, normalization, and acceptance calculations in these data. The given error bars are partly statistical (second column of uncertainties) and partly systematic. The systematic part comes from the yield fits to the (gamma,K+) missing mass spectra, which were done using a template fitting procedure explained in the thesis and note. The first columns of uncertainties show the TOTAL error of systematic and statistical error combined. The line shape data are tabulated for an integration over the specified range of kaon center-of-mass angles. The data for each of the three charge states span the same range of kaon production angles. However, the angular integration range differs from W bin to W bin. The overall systematic uncertainty in these results was estimated to be 11.6%. For details, consult the resources cited above, or the publication.