Strange-Meson Spectroscopy – from COMPASS to AMBER

Abstract

COMPASS is a multi-purpose fixed-target experiment at CERN’s M2 beam line aimed at studying the structure and spectrum of hadrons. It has collected the so far world’s largest data set on diffractive production of the K−π−π+ final state, which in principle gives access to all strange mesons. Based on this data set, we performed an elaborate partial-wave analysis. It reveals signals in the mass region of well-known states, such as the K*2(1430). In addition, we found indications for a resonance-like signal in the mass region of the K(1630). This state would be a supernumerary state and hence could be a candidate for an exotic strange meson. The partial-wave analysis is limited in some areas by the limited kinematic coverage of the final-state particle identification of the COMPASS setup. To overcome this limitation, we propose a new high-precision strange-meson spectroscopy measurement at the AMBER experiment, which will be located at CERN’s M2 beam line.