Exclusive Measurements of $pd\to ^3He ��$ : the $ABC$ Effect Revisited

Authors :: Bashkanov, M.
Bogoslawsky, D.
Cal��n, H.
Cappellaro, F.
Clement, H.
Demiroers, L.
Ekstr��m, C.
Fransson, K.
Greiff, J.
Gustafsson, L.
H��istad, B.
Ivanov, G.
Jacewicz, M.
Jiganov, E.
Johansson, T.
Kaskulov, M. M.
Keleta, S.
Koch, I.
Kullander, S.
Kup��, A.
Kuznetsov, A.
Marciniewski, P.
Meier, R.
Morosov, B.
Oelert, W.
Pauly, C.
Petukhov, Y.
Povtorejko, A.
Ruber, R. J. M. Y.
Scobel, W.
Skorodko, T.
Shwartz, B.
Sopov, V.
Stepaniak, J.
Tchernyshev, V.
Th��rngren-Engblom, P.
Tikhomirov, V.
Turowiecki, A.
Wagner, G. J.
Wolke, M.
Yamamoto, A.
Zabierowski, J.
Zlomanczuk, J.
Publication Year :: 2005
Publisher :: arXiv, 2005.
Abstract: Exclusive measurements of the reactions $pd\to$ $^3He ��^+ ��^-$ and $pd\to$ $^3He ��^0��^0$ have been carried out at $T_p=0.895$ GeV at the CELSIUS storage ring using the WASA detector. The $��^+��^-$ channel evidences a pronounced enhancement at low invariant $��$ masses - as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar $��^0��^0$ channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. $��$ calculations give a good description of the data, if a boundstate condition is imposed for the intermediate $��$ system.<br />extended version, 8 pages, 7 figures, theoretical model calculations added