Speaker
Description
We have recently measured the missing-mass spectrum of the 12C(p,d) reaction near the eta' production threshold at GSI, Germany, in coincidence with high-momentum protons to enhance the formation of the eta'-11C bound states. A 2.5 GeV proton beam induces the reaction, while forward-emitted deuterons are momentum-analyzed with the FRS used as a high-resolution spectrometer. High-momentum protons from the decay of eta'-mesic nuclei are identified by the WASA detector surrounding the target. The resulting semi-exclusive spectrum shows indications of structures below the threshold. Comparison with theoretical spectra based on different eta'-nucleus optical potentials suggests a real-part potential depth of about −61 MeV, with a local significance of 3.5σ and a global significance of 2.1σ after accounting for the look-elsewhere effect. The contribution is based on our recently published paper (R. Sekiya, K. Itahashi et al., Phys. Rev. Lett. 136, 142501 (2026).