The He-4(pi+,pi-) reaction at low energies

Graeter, J.; Bilger, R.; Clement, H.; Meier, R.; Wagner, G. J.; Friedman, E.; Schepkin, M.; Amaudruz, P. A.; Felawka, L.; Ottewell, D.; Smith, G. R.; Ambardar, A.; Hofman, G. J.; Kermani, M.; Tagliente, G.; Bonutti, Faustino; Camerini, Paolo; Grion, N.; Rui, Rinaldo; Hong, P.; Mathie, E. L.; Tacik, R.; Clark, J.; Sevior, M. E.; Patarakin, O.

doi:10.1016/S0370-2693(97)01540-2

Using the CHAOS spectrometer at TRIUMF the total cross sections and outgoing pion momentum distributions for the 4He(π+,π−) reaction were measured for π+ kinetic energies from 70 to 130 MeV. At energies around 100 MeV the total cross sections show an excess by a factor 3 over conventional model calculations which could be ascribed to a contribution from a hypothetical d′ dibaryon.

The He-4(pi+,pi-) reaction at low energies / J., G., R., B., H., C., R., M., G. J., W., E., F., M., S., P. A., A., L., F., D., O., G. R., S., A., A., G. J., H., M., K., G., T., Bonutti, F., Camerini, P., N., G., Rui, R., P., H., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 420:(1998), pp. 37-42. [10.1016/S0370-2693(97)01540-2]