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HK: Fachverband Physik der Hadronen und Kerne
HK 25: Hadron Structure and Spectroscopy IV
HK 25.1: Group Report
Tuesday, March 12, 2024, 17:30–18:00, HBR 14: HS 1
Chiral symmetry breaking: experimental tests at COMPASS and future prospects* — •Dominik Ecker for the COMPASS collaboration — Technische Universität München
When we are dealing with the lightest quarks at low energies, the properties of Quantum Chromodynamics are encoded by chiral symmetry and the manifestation of its breaking. We can exploit this symmetry to build an effective field theory, which can be expanded as a perturbation theory. Chiral Perturbation Theory allows to describe a variety of phenomena observed for light mesons at low-energies, including their decays and their couplings to photons or other matter fields. Among the light hadrons, the pion plays a special role, as it is the lightest meson and emerges as a Goldstone boson from the breaking of the Chiral Symmetry. Its properties are directly related to the underlying symmetry.
In this talk, we will focus on the experimental verification of pion properties, in particular so-called anomalous couplings, which arise as a consequence of the chiral anomaly. We will review the state of the art, explain previous measurements and point out experimental challenges. We will then highlight the recent measurement of the anomalous value for F3π by the COMPASS collaboration at CERN. A proposed measurement at the AMBER experiment will allow us to extent the studies to the next heaviest quark generation in interactions with kaons.
*funded by the DFG under Germany’s Excellence Strategy - EXC2094 - 90783311 and BMBF Verbundforschung 05P21WOCC1 COMPASS.
Keywords: COMPASS; Primakoff; Chiral symmetry breaking; Chiral anomaly