Erlangen 2026 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 3: Hadron Structure and Spectroscopy II

HK 3.2: Vortrag

Montag, 16. März 2026, 16:45–17:00, PHIL A 401

Pseudoscalar meson-pair production beyond the resonance region at COMPASS — •Henri Pekeler for the COMPASS collaboration — Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Germany

The COMPASS experiment at CERN’s SPS provides a uniquely large data set to study the light-meson spectrum in diffractive production reactions of 190 GeV/c beam pions with protons. Among the many different final states accessible, ηπ⁻ and η^′π⁻ are clean channels to investigate the lightest hybrid-meson candidate, the π₁(1600). One challenge in identifying meson resonances is the separation of resonant and non-resonant processes.

To better constrain the non-resonant production mechanism of these final states, we analyze the high-mass region, i.e. 4 GeV/c²<m_{η^(′)π⁻}<6 GeV/c², using the double-Regge exchange model by Shimada er al., [Nucl. Phys. B 142 (1978)]. The model describes the dependence of the amplitude of a given double-Regge exchange on the invariant variables in terms of Regge trajectories. In addition, form factors are introduced at every vertex to parameterize the t-dependence of the coupling. For the first time, we perform an event-based likelihood fit to the COMPASS data set and show that the high-mass data can be described by only 13 parameters.

Supported by BMFTR.

Keywords: Double-Regge exchange; COMPASS; Event-based likelihood fit