g11a

Spokespersons

Biplab Dey, Curtis Meyer

Year

2004

Abstract

High-statistics measurements of differential cross sections and recoil polarizations for the reaction γ p → K⁺ Σ⁰ have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (sqrt(s)) from 1.69 to 2.84 GeV, with an extensive coverage in the K⁺ production angle. Independent measurements were made using the K⁺pπ^-(γ) and K⁺p(π^-,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 sqrt(s) coverage. Above sqrt(s)~ 2.5 GeV, t- and u-channel Regge scaling behavior can be seen at forward- and backward-angles, respectively. Our recoil polarization (P_Σ) measurements represent a substantial increase in kinematic coverage and enhanced precision over previous world data. At forward angles we find that P_Σ is of the same magnitude but opposite sign as P_Λ, in agreement with the static SU(6) quark model prediction of P_Σ ~ -P_Λ. This expectation is violated in some mid- and backward-angle kinematic regimes, where P_Σ and P_Λ 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.

Publication

1. B. Dey, C. A. Meyer, M. Bellis, M. E. McCracken, M. Williams, the CLAS Collaboration Differential cross sections and recoil polarizations for the reaction γ p -> K⁺ Σ⁰. // PRC 82, 025202 (2010)

Quantities

dσ/dcos(θ_K⁺)   P_Σ

Measurements