Erlangen 2026 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 38: Hadron Structure and Spectroscopy VIII

HK 38.5: Talk

Thursday, March 19, 2026, 17:30–17:45, PHIL A 401

Study of exclusive η meson production in proton-proton collisions with the HADES spectrometer — •Szymon Treliński^1,2, James Ritman^2,3,4, and Izabela Ciepał¹ for the HADES collaboration — ¹IFJ PAN Krakow — ²Ruhr-Universität Bochum — ³GSI Helmholtzzentrum — ⁴Forschungszentrum Jülich

Proton–proton collisions at a center-of-mass energy of 3.46 GeV, measured in February 2022 with the HADES detector at GSI, provide great opportunity to study exclusive η meson production. This energy lies in the transition region between near-threshold energies, described by effective Lagrangian models, and the soft regime, where Regge phenomenology is applied. Measurements in this range help to bridge these descriptions and contribute to a more coherent understanding of nonperturbative QCD dynamics.

The analysis focuses on the exclusive reaction pp→ ppη → ppπ⁺π⁻π⁰, with the η reconstructed in its π⁺π⁻π⁰ decay channel. This channel provides high statistics due to its large branching ratio combined with good reconstruction efficiency. The study considers different event topologies to extend the accessible phase space.

The talk will present the event selection strategy, the application of the kinematic fit, the background subtraction procedure, and the multidimensional unfolding technique, together with early-stage results on the total and differential cross sections for exclusive η production.

Keywords: HADES; exclusive; eta; proton-proton; QCD