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HK: Fachverband Physik der Hadronen und Kerne
HK 29: Hadron Structure and Spectroscopy V
HK 29.1: Gruppenbericht
Donnerstag, 19. März 2026, 13:45–14:15, PHIL C 301
Measurement of the cross section for γ p → φ π+ π− p and search for the Y(2175) in photoproduction with the GlueX experiment — •Klaus Götzen1 and Frank Nerling1,2 for the GlueX collaboration — 1GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany — 2Goethe-Universität Frankfurt, Germany
The Y(2175), recently renamed to φ(2170), is discussed to be a strange partner state of the famous charmonium-like exotic vector state Y(4260). The former has originally been observed in initial-state radiation by the BaBar experiment in 2006. Meanwhile, it has been reported in different e+e− annihilation experiments. Based on the first measurement of the differential cross section for the exclusive reaction γ + p → φ(1020) π+π− p, we have performed a search for this strangeonium-like exotic candidate φ(2170) → φ π+π− in the GlueX data [1]. It is addressed here for the first time in a photoproduction experiment. We do not find evidence for this state at the resonance parameters quoted by the Particle Data Group and provide upper limits on the photoproduction cross section. Instead, we find a structure at a mass of m(φπ+π−)= 2.24 GeV/c2 with a statistical significance of about 5 σ. The parameters of this structure differ from those quoted by the Particle Data Group for the φ(2170) and are consistent with a previous observation in e+e− annihilation. In addition, there is evidence for a second structure at 1.82 GeV/c2.
[1] GlueX Collab., subm. to PRL, Dec 2025; arXiv:2512.04136 [hep-ex]
Keywords: Exotic mesons; Photoproduction; Hadron spectroscopy; XYZ states