Application of Straw Tube Detectors to Hyperon Studies

Abstract

A high statistics measurement of the pp → pK + Λ reaction was done with the COSY-TOF experiment. The proton beam was polarized up to more than 80%, and its momentum was 2.95 GeV/c. The reconstruction of the pK + Λ events was done only with the straw tube tracker due to the higher spatial resolution of the straw tube tracker compared to other subdetectors. The Dalitz plot of the pK + Λ events was analyzed to understand the reaction mechanism and presented in this paper. The Dalitz plot shows that the COSY-TOF experiment provides complete kinematic coverage of the phase space of this reaction which made it ideal for pp → pK + Λ reaction analysis. The inuence of dierent physical eects as pΛ nal state interaction, excited nucleon states (N * -resonances) and a coupled channel eect of NΣ-pΛ (NΣ cusp eect) produce signicant structures in the Dalitz plot. The angular distribution of the particles in the CMS and helicity frame was also presented in this paper.