Chiral symmetry restoration in nuclear medium observed in pionic atoms

Abstract

We interpret the spectral information of the pionic 1s and 2p states in the 121Sn nucleus observed with unprecedented precision and resolution with respect to the in-medium pion-nucleus interaction to deduce partial restoration of the chiral symmetry in the high density of the nuclear matter. Most recent theoretical and experimental results are integrated to obtain the precision information on the partial restoration of the chiral symmetry. We find reduction of the chiral condensate in the Sn nucleus by a factor of 77 ± 2% at the nucleon density of 0.098 fm−3. The result is compared with the chiral theories showing fairly good agreement. © 2024 Italian Physical Society. All rights reserved.