Toward a direct measurement of partial restoration of chiral symmetry at J-PARC E16 via density-induced chiral mixing

密度効果に誘発されるカイラル混合によるJ-PARC E16におけるカイラル対称性の部分的回復の直接観測に向けて

江島 廉*; Gubler, P. ; 佐々木 千尋*; 志垣 賢太*

Ejima, Ren*; Gubler, P.; Sasaki, Chihiro*; Shigaki, Kenta*

The degeneracy of chiral partners is an ideal signal for measuring the restoration of the spontaneously broken chiral symmetry in QCD. In this work, we investigate the observability of the -f(1420) degeneracy in the J-PARC E16 experiment, which measures di-electrons emitted from 30 GeV pA collisions. We for this purpose make use of an effective Lagrangian approach, which naturally incorporates the broken charge-conjugation symmetry in nuclear matter and the ensuing anomaly-induced mixing between vector and axial-vector mesons, to compute the spectral function relevant for the experimental measurement. The real-time dynamics of the pA collision is obtained from a transport simulation. Including experimental background and resolution effects on top of that, we find that a signal of the -f(1420) mixing can be observed around 2.5 with the Run2 statistics planned for the J-PARC E16 experiment with an ideal mixing strength.