Frankfurt 2014 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 38: Hadronenstruktur und -spektroskopie
HK 38.4: Talk
Thursday, March 20, 2014, 15:00–15:15, HZ 3
Spectroscopy of final states with neutral particles in COMPASS — •Sebastian Uhl — Technische Universität München, Physik Department E18, 85748 Garching
To study the spectrum of light hadrons the COMPASS experiment at CERN has collected a huge data set with a negative pion beam impinging on a liquid hydrogen target. Resonances are diffractively produced at squared four-momentum transfers to the target between 0.1 (GeV/c)2 and 1 (GeV/c)2. The two-stage magnetic spectrometer with two electromagnetic calorimeters allows to study charged as well as semi-neutral final states, thus allowing an immediate consistency check between the flagship channel π−π−π+ and its isospin partner π−π0π0.
The decomposition of the three-pion mass spectra is done with the help of a partial-wave analysis. Partial waves up to spin six are included in the first step of the analysis, where the spin-parity decomposition of the data is performed in bins of the three-pion mass and the squared four-momentum transfer t′. The binning in t′ provides a handle to better separate the resonant and non-resonant parts of the intensity in the second stage of the analysis, the modeling of the mass dependence of the spin-density matrix in order to extract resonance parameters.
This work was supported by the BMBF, the DFG Cluster of Excellence “Origin and Structure of the Universe” (Exc 153), and the Maier-Leibnitz-Laboratorium der Universität und der Technischen Universität München.