2025/09/09 by R. Sekiya, Sekiya, R., K. Itahashi +151
Physics and Astronomy · #FOS: Physical sciences #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th) #Nuclear physics research studies #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2509.07824
openalex publication_date 2025/09/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The missing mass of the 12\rm C(p,d) reaction has been measured near the η'-meson emission threshold in coincidence with a high-momentum proton to selectively collect η'-11\rm C mesic nucleus formation events at GSI, Germany. A 2.5 GeV proton excites a carbon nucleus to form an η'-mesic nucleus emitting a deuteron forward with an energy of ∼ 1.6 GeV. The deuteron is momentum-analyzed by the Fragment Separator used as a high-resolution spectrometer to deduce the excitation energy of the residual system. The large-acceptance detector WASA surrounding the target identifies high-momentum protons emitted in the decay of the η'-mesic nucleus. The measured semi-exclusive spectrum exhibits structures below the threshold though the statistical significance is limited. The spectrum is fitted by theoretically calculated spectra varying optical-potential parameters of the η'-nucleus interaction. The analysis results indicate η'-mesic nuclei formation for the real potential depth of ∼ -61 MeV with a local statistical significance of 3.5 σ and, taking into account the look-elsewhere effect, a global significance of 2.1 σ.