An experimental research trying to find precursory phenomena of the chiral transition in nuclei is going on by utilizing a 2.4 GeV Laser-Electron Photon beam at SPring-8. The photoproduction measurement of 2π0 has been conducted for this purpose at a high momentum- transfer region, where the interaction of an incident photon with a nucleon in the nuclear target is expected to take place inside the nucleus effectively. A preliminary result of the 2π0 photoproduction measurement is reported and a softening of the σ meson in nuclear medium is discussed as a candidate for the precursors. A plan for a η′ measurement is also discussed in connection with the axial U(1) problem, which might be affected by partial restoration of chiral symmetry in nuclei.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)