$Λp$ Elastic Scattering in the CLAS Detector

Abstract

The elastic scattering process $Λp\toΛp$ offers insights on multiple problems in nuclear physics. $\mathrm{SU}(3)_F$ symmetry implies a close agreement between the $Λp$ and $pp$ scattering cross sections. The $Λp$ elastic scattering cross section can also illuminate the structure of neutron stars. A data-mining project was started using multiple CLAS data sets taken for other purposes with photon beams on a long liquid hydrogen target. A $Λ$ produced in a process such as $γp\to K^+Λ$ can interact with a second proton inside the target before either decaying or leaving the target. The good angular acceptance and momentum resolution of CLAS make it well-suited for this type of analysis, even though it was not designed for such a measurement. The scattered $Λ$ can be identified from the $π^-p$ invariant mass. The four-vector of the initial $Λ$ is then reconstructed in the process $Xp\toΛp$, which shows a strong peak at the $Λ$ mass with roughly twice the number of events as the existing world data sample. This observation opens up the possibility of other measurements using secondary beams of short-lived particles. This paper will discuss the current status of the analysis, and our plans for future work on this project.