Münster 2017 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 28: Hadron Structure and Spectroscopy IV
HK 28.6: Vortrag
Mittwoch, 29. März 2017, 18:15–18:30, F 5
Dispersive approach to the triangle diagram in the decay of the a1(1260) resonance — •Mathias Wagner, Mikhail Mikhasenko, and Bernhard Ketzer — Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, 53115 Bonn, Germany
Recently a resonance-like signal was observed by the COMPASS experiment in the JPC= 1++ partial wave decaying to f0(980)π, the a1(1420). One possible explanation of this signal is a triangle singularity located close to the physical axis, which is produced when the decay of the a1(1260) into K* K is kinematically allowed.
In my talk I am going to present a dispersive approach to calculate the amplitude of the reaction a1(1260) → f0(980) + π via a triangle diagram. First the general procedure how to reconstruct the full amplitude using a dispersion relation will be explained. This requires the calculation of the discontinuity of the corresponding matrix element, which can be done by applying the Cutkosky cutting rules.
The result will be compared to calculations employing Feynman rules for hadronic processes.
In the end a fit of this theoretical result to the COMPASS data of 3π production will be presented.
Supported by BMBF.