Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 23: Hadron Structure and Spectroscopy IV

HK 23.5: Talk

Tuesday, March 15, 2016, 17:45–18:00, S1/01 A5

Extraction of the amplitude of the π⁺π⁻ subsystem in diffractively produced π⁻π⁺π⁻ at COMPASS — •Fabian Krinner — Physik-Department E18, Technische Universität München

The two-stage Compass spectrometer has collected a huge data set of tens of millions of events for the channel π⁻p→π⁻π⁺π⁻p. Therefore, spectroscopy analyses in this channel are dominated by systematic effects. The established method to analyze these data is Partial-Wave Analysis (PWA). For multi-particle final states PWA usually assumes subsequent two-particle decays, i.e. in case of π⁻π⁺π⁻ one additional intermediate state which decays into π⁺π⁻. Fixed mass shapes for this intermediate state, the so-called isobar, have to be assumed. These shapes, which in the most simple case may be given by a Breit-Wigner amplitude, have to be put into the analysis beforehand and therefore may introduce a model dependence leading to increased systematic uncertainties. We present a first analysis of diffractively produced π⁻π⁺π⁻ events using a new method, which instead allows to extract binned isobar amplitudes directly from the data in a more model-independent way.

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.