The pi -> pi pi process in nuclei and the restoration of chiral symmetry
N Grion, M Bregant, P Camerini, E Fragiacomo, S Piano, R Rui, EF Gibson, G Hofman, EL Mathie, R Meier, ME Sevior, GR Smith, R Tacik
NUCLEAR PHYSICS A | ELSEVIER | Published : 2005
The results of an extensive campaign of measurements of the π → ππ process in the nucleon and nuclei at intermediate energies are presented. The measurements were motivated by the study of strong ππ correlations in nuclei. The analysis relies on the composite ratio CππA, which accounts for the clear effect of the nuclear medium on the ππ system. The comparison of the CππA distributions for the (ππ)I=J=0 and (ππ)I=0,J=2 systems to the model predictions indicates that the CππA behavior in proximity of the 2mπ threshold is explainable through the partial restoration of chiral symmetry in nuclei. © 2005 Elsevier B.V. All rights reserved.