Analysis of diffractively dissociated K−pi+pi− events produced by a 190 GeV/c2 hadron beam on a fixed lh2 target at the COMPASS-experiment
Prometeusz Jasinski (Mainz)

The COmmon Muon Proton Apparatus for Structure and Spectroscopy (COMPASS)-Experiment located at the SPS synchrotron at CERN took data to study a large number of physics processes and COMPASS is about to contribute significantly to the field of hadron spectroscopy.

The hunt for exotic, glue-rich resonances was the main topic of the hadron runs in the years 2008 and 2009. Most of the data in 2008 was taken with a negative hadron beam with an energy of 190 GeV/\(c^2\) impinging on a liquid hydrogen target. Neutral as well as charged events with single diffractive signature triggered by a recoiling proton were recorded. Since the beam consists mainly of pions processes like diffractive dissociation into 3 pions were dominating.

The beam also hold a small fraction of kaons that were identified using ChErencov Differential counters with Achromatic Ring focus (CEDAR).
The small fraction of Kaons of about 2.4% allows the study of diffractive dissociation into \(K^- \pi^+ \pi^-\).

I will present selection and analysis of those events from all 2008 data. The invariant mass distributions show well known narrow resonances as \(K_1(1270), K_1(1400)\) and \(K_2(1770)\). To understand the whole spectrum hiding many weaker and/or wider resonances techniques of partial wave analysis (PWA) are applied. I will illustrate the basic ideas of this analysis before showing results from ongoing analysis.