First results on the experimental search for η′-mesic nuclei with the ¹²C(p, d) reaction

We performed a missing-mass spectroscopy experiment of the ¹²C(p, d) reaction in order to search for η′-mesic nuclei. Excitation spectrum of ¹¹C around the η′-meson production threshold was successfully obtained with a high-statistical sensitivity and sufficiently good energy resolution. Since no peak structure associated with the formation of η′-mesic nuclei was observed, we set constraints on the formation cross sections of η′-mesic states and on the η′-nucleus interaction.