Measurement of the $\vec{\gamma} p \to K^+ \Lambda$ Reaction at Backward Angles

TL;DR

This study measures the cross sections and beam asymmetry of the gamma p to K+ Lambda reaction at backward angles using polarized photons, providing new data to understand hadron reaction mechanisms.

Contribution

It presents the first measurement of beam asymmetry at backward angles for this reaction, expanding the kinematic range of experimental data.

Findings

Cross sections measured at backward angles with polarized photons.

First measurement of beam asymmetry at backward angles.

Data complement existing measurements at other angles.

Abstract

Cross sections for the $\gamma p \to K^+ \Lambda$ have been measured at backward angles using linearly polarized photons in the range 1.50 to 2.37 GeV. In addition, the beam asymmetry for this reaction has been measured for the first time at backward angles. The $\Lambda$ was detected at forward angles in the LEPS spectrometer via its decay to $p\pi^-$ and the K^+ was inferred using the technique of missing mass. These measurements, corresponding to kaons at far backward angles in the center-of-mass frame, complement similar CLAS data at other angles. Comparison with theoretical models shows that the reactions in these kinematics provide further opportunities to investigate the reaction mechanisms of hadron dynamics.