Mainz 2022 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 72: Hadron Structure and Spectroscopy XII

HK 72.1: Gruppenbericht

Donnerstag, 31. März 2022, 16:00–16:30, HK-H8

Role of a triangular singularity in the γ p → p π⁰ η reaction — •Volker Metag and Mariana Nanova for the CBELSA/TAPS collaboration — II. Physikalisches Institut, Universität Giessen, Giessen

Recently structures in invariant mass distributions and excitation energy spectra have been attributed to triangular singularities as discussed in e.g., [1,2] and in the review by Guo et al. [3]. These singularities emerge under specific kinematic conditions when new reaction channels open up. It will be shown that a triangular singularity associated with the opening of the γ p → p a₀ → p π⁰ η channel can explain the observation of a structure in the M_pη invariant mass distribution near 1700 MeV/c² in the γ p → p π⁰ η reaction [4].

[1] G. D. Alexeev et al., The COMPASS Collaboration, Phys. Rev. Lett 127, 082501 (2021).
[2] M. Mikhasenko, B. Ketzer and A. Sarantsev, Phys. Rev. D 91, 094015 (2015).
[3] F. K. Guo et al., Rev. Mod. Phys. D 90, 015004 (2018).
[4] V. Metag et al., arXiv:2110.05155.
Supported by DFG through SFB/TR16.