Elastic Scattering of Low Energy Pions by Nuclei and the In‐Medium Isovector πN Amplitude
/ Authors
E. Friedman, M. Bauer, J. Breitschopf, H. Clement, H. Denz, E. Doroshkevich, A. Erhardt, G. Hofman, S. Kritchman, R. Meier
and 5 more authors
G.J.Wagner, U. G.YaariHebrew, U. Tuebingen, Triumf, U. O. Regina
/ Abstract
Measurements of elastic scattering of 21.5 MeV π± by Si, Ca, Ni and Zr were made using a single arm magnetic spectrometer and absolute calibration was made by parallel measurements of Coulomb scattering of muons. Optical model fits to the data reveal the ‘anomalous’ s‐wave repulsion known from pionic atoms. Introducing a chiral‐motivated density dependence of the isovector scattering amplitude, and considering the energy dependence of the free πN interaction greatly improve fits to the data and remove the ‘anomaly’.