Near threshold angular distributions for the 2H(γ,Λ)X reaction

A study of the H-2(gamma, Lambda) X reaction was performed using a tagged photon beam at the Research Center for Electron Photon Science ( ELPH), Tohoku University. The photoproduced Lambda was measured in the p pi(-) decay channel by the upgraded Neutral Kaon Spectrometer ( NKS2+). The momentum integrated differential cross section was determined as a function of the scattering angle of Lambda in the laboratory frame for five energy bins. Our results indicated a peak in the cross section at angles smaller than cos(Lambda)(LAB) = 0.96. The experimentally obtained angular distributions were compared to isobar models, Kaon- Maid ( KM) and Saclay- Lyon A ( SLA), in addition to the composite Regge- plus- resonance ( RPR) model. Both SLA( rK1K. =- 1.4) and RPR describe the data quite well in contrast to the KM model, which substantially under- predicted the cross section at the most forward angles. With the anticipated finalized data on Lambda integrated and momentum dependent differential cross sections of H-2(gamma, Lambda) X [ M. Kaneta et al., Nucl. Phys. A 914, 69 ( 2013)], we present our findings on the angular distributions.