Experimental search for eta-prime mesic nuclei using WASA at GSI/FAIR*

We are preparing an experimental to search for an eta' meson bound to a nucleus, an eta' mesic nucleus in GSI/FAIR. eta' meson is known to have a much larger mass than other pseudo scalar mesons in the same multiplet. The large mass is thoretically understood in terms of combined contributions from spontaneous chiral symmetry breaking of the QCD vacuum and axial U(1) anomaly. We investigate the origin of the mass of eta' mesons by making spectroscopy of eta' meson bound to a nucleus. We have been working on the experiment in GSI/FAIR in Darmstadt, Germany.
The experiment utlizes 12C(p,d) reactions to produce eta' mesic nuclei. We have performed first experimental search by the inclusive reactions as reported in Refs. [1,2]. We make use of a large detector apparatus for detecting their decays mainly into eta'NN -> NN, where N denotes a nucleon. A large acceptance charged particle detector of WASA is in preparation at GSI. We will report the present status of the project.

References
1. Y.K. Tanaka et al., PRL 117, 202501 (2016)
2. Y.K. Tanaka et al., PRC 97, 015202 (2018)