posted on 2010-01-01, 00:00authored byB. Dey, Curtis MeyerCurtis Meyer, Michael E. McCracken, CLAS Collaboration
<p>High-statistics measurements of differential cross sections and recoil polarizations for the reaction γp→K<sup>+</sup>Σ<sup>0</sup> have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.69 to 2.84 GeV, with an extensive coverage in the K<sup>+</sup> production angle. Independent measurements were made using the K<sup>+</sup>pπ<sup>-</sup>(γ) and K<sup>+</sup>p(π<sup>-</sup>,γ) final-state topologies, and were found to exhibit good agreement. Our differential cross sections show good agreement with earlier CLAS, SAPHIR, and LEPS results, while offering better statistical precision and a 300-MeV increase in √s coverage. Above √s≈2.5 GeV, t- and u-channel Regge scaling behavior can be seen at forward and backward angles, respectively. Our recoil polarization (P<sub>Σ</sub>) measurements represent a substantial increase in kinematic coverage and enhanced precision over previous world data. At forward angles, we find that P<sub>Σ</sub> is of the same order of magnitude but opposite sign as P<sub>Λ</sub>, in agreement with the static SU(6) quark model prediction of P<sub>Σ</sub>≈-P<sub>Λ</sub>. This expectation is violated in some mid- and backward-angle kinematic regimes, where P<sub>Σ</sub> and P<sub>Λ</sub> are of similar magnitudes but also have the same signs. In conjunction with several other meson photoproduction results recently published by CLAS, the present data will help constrain the partial-wave analyses being performed to search for missing baryon resonances.</p>