SMuK 2023 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 7: Hadron Structure and Spectroscopy I
HK 7.3: Vortrag
Montag, 20. März 2023, 17:15–17:30, SCH/A316
Understanding the Ambiguities in the Partial-Wave Decomposition of the Ks0 K− Final State* — •Julien Beckers for the COMPASS collaboration — Technical University of Munich
COMPASS is a multi-purpose fixed-target experiment at the CERN SPS. One of its main goals is to probe the excitation spectrum of light mesons in diffractive scattering reactions. This requires decomposing the data into partial-wave amplitudes with well-defined quantum numbers and searching for resonances in these amplitudes. Using this method, decays of light mesons into various final states are studied at COMPASS. In the case of final states with two spinless particles, mathematical ambiguities appear in the partial-wave decomposition, meaning that several sets of values for the amplitudes lead to the same measured intensity distribution, i.e. are indistinguishable by the data.
In this talk, we will present a new investigation of these ambiguities in the Ks0 K− final state, which allows us to study aJ- and πJ-like resonances with spin J with high precision and which complements the ηπ−, η′π− and π−π−π+ final states that have already been studied at COMPASS. We will explain how they arise and show how they evolve with the mass of the system, as well as present approaches to resolve them completely or to reduce the number of ambiguous solutions for the amplitudes, by introducing terms that break the exact invariance.
* funded by the DFG under Germany’s Excellence Strategy - EXC2094 - 390783311 and BMBF Verbundforschung (05P21WOCC1 COMPASS)