A calculation of π-3He elastic scattering at low energies employing microscopic 3He-wave functions

Abstract We have calculated the differential cross sections and analyzing power for the elastic scattering of pions from 3 He at incident pion energies of 20, 25, 30, 35, 45 and 65 MeV. For this purpose we have used a first-order optical potential, constructed from a microscopic (theoretical) 3 He wave function. We took the Fermi motion into account in an exact way by calculating the complete Fermi integral. We have used different forms for the pion-nucleon interaction. We took the effect of true absorption into account via a nuclear density-squared potential, and we add the Coulomb potential to the nuclear optical potential according to the method of Vincent and Phatak. We made a detailed comparison with the model of Landau and Thomas. Our main conclusions are: (i) the factorization method is inadequate, (ii) the results are sensitive with respect to the off-shell pion-nucleon T -matrix, (iii) the density-squared absorption model, though giving good agreement with measurements, does not allow a meaningful physical interpretation of the parameter values.