Mainz 2012 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 23: Hadronenstruktur und -spektroskopie

HK 23.3: Talk

Wednesday, March 21, 2012, 14:45–15:00, RW 2

Diffractive Dissociation into 3 Pion Final States at COMPASS — •Florian Haas — Technische Universität München

Diffractive dissociation reactions studied at the COMPASS experiment, CERN, provide access to the light meson spectrum. During a pilot run in 2004, using a pion beam and a lead target, 500k events of π⁻ π⁻ π⁺ final state events with masses below 2.5 GeV/c² were recorded, yielding a significant signal for the π₁(1600) spin-exotic resonance. After a significant upgrade of the spectrometer in 2007, the following two years were dedicated to meson spectroscopy. Using again a pion beam, but now with a liquid hydrogen target, an unique statistics of ∼ 60M events of the same final state was gathered in 2008. During a short campaign in 2009, the liquid target was exchanged by several solid state targets in order to compare final states produced on targets with different atomic numbers. After a short summary of a partial wave analysis (PWA) of 2004 data, the focus will be on a PWA of 2008 data in the same kinematic range of momentum transfer
(0.1 GeV²/c² < t′ < 1.0 GeV²/c²). In addition the progress of the analysis of data recorded with solid state targets in 2009 and a comparison with 2008 and 2004 data will be presented.