RARiS 研究会「実験、反応・構造計算、格子QCD で解き明かすハドロン分光 2024」

Missing-mass spectroscopy of 12C(p,dp) reaction to search for η′-mesic nuclei with the WASA detector at GSI-FRS

Nov 21, 2024, 10:35 AM

20m

　三神峯ホール (東北大学先端量子ビーム科学研究センター)

Plenary Session

Speaker

Ryohei Sekiya (Kyoto University, RIKEN)

Description

"${\eta }^{\prime }(958)$ meson has an exceptionally large mass compared with the other light pseudo-scalar meson nonets. The origin of the large mass is considered to have a close relation to the chiral symmetry breaking and the axial U(1) anomaly in the QCD. In a nuclear matter, where the chiral symmetry is partially restored, a mass reduction of an ${\eta }^{\prime }$ meson is predicted by several theoretical models. Since such a mass reduction leads to an attractive potential for the ${\eta }^{\prime }$ meson in a nucleus, the existence of bound states between ${\eta }^{\prime }$ mesons and nuclei (=${\eta }^{\prime }$-mesic nuclei) has been suggested.

To search for ${\eta }^{\prime }$-mesic nuclei, we conducted missing-mass spectroscopy of ${}^{12}\mathrm{C}(p,d)$ reaction in a coincidence detection of protons from the two nucleon absorption decay of ${\eta }^{\prime }$-mesic nuclei using a large solid angle detector WASA at the fragment separator (FRS) in GSI in 2022 February. We made use of 2.5 GeV proton beams with an intensity of $3.0\times {10}^8/s$ and a ${}^{12}\mathrm{C}$ target with a thickness of 4 g/cm${}^2$. The momenta of the forward emitted deuterons were analyzed by the FRS and the protons with momenta of $\sim$1 GeV/$c$ from the decay of ${\eta }^{\prime }$-mesic nuclei with the WASA detector simultaneously.

This presentation will provide the experimental details and the current situation of the data analysis."