Dresden 2013 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 77: Hadronenstruktur und -spektroskopie

HK 77.7: Vortrag

Donnerstag, 7. März 2013, 18:30–18:45, HSZ-304

Measurement of radiative widths at COMPASS — •Stefanie Grabmüller — Technische Universität München, Physik-Department E18, 85748 Garching

COMPASS is a multi-purpose fixed-target experiment at CERN SPS, that investigates the structure and spectroscopy of hadrons. Dissociation of pions on nuclear or hydrogen targets provides clean access to the light meson spectrum. During a short run with π⁻ beam on lead in the year 2004, about 4 million exclusive π⁻π⁻π⁺ events have been collected. For the 3 million events with low momentum transfer t′ < 0.01 GeV²/c², coherent scattering off the nucleus as a whole can be assumed, with contributions from Reggeon (Pomeron) and quasi-real photon exchange. For the lowest t′ < 0.001 GeV²/c², the electromagnetic interaction part becomes apparent.

The partial-wave analysis of these data leads to the observation of resonances as the a₂(1320) dominantly produced by quasi-real photon exchange. The extraction of their radiative widths will be presented.

This work is supported by BMBF, Maier-Leibnitz-Labor München and the DFG Cluster of Excellence Exc153.