Exclusive measurements of pd ---> He-3 pi pi: The ABC effect revisited
Bashkanov
M.
Bogoslawsky
D.
Calen
H.
Cappellaro
F.
Clement
H.
Demiroers
L.
Ekstrom
Curt
Fransson
K.
Greiff
J.
Gustafsson
L.
Hoistad
B.
Ivanov
G.
Jacewicz
M.
Jiganov
E.
Johansson
T.
Kaskulov
M.M.
Keleta
S.
Koch
I.
Kullander
S.
Kupsc
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.
Thorngren-Engblom
P.
Tikhomirov
V.
Turowiecki
A.
Wagner
G.J.
Wolke
M.
Yamamoto
A.
Zabierowski
J.
Zlomanczuk
J.
2006
Exclusive measurements of the reactions $pd\to$ $^3He \pi^+ \pi^-$ and $pd\to$ $^3He \pi^0\pi^0$ have been carried out at $T_p=0.895$ GeV at the CELSIUS storage ring using the WASA detector. The $\pi^+\pi^-$ channel evidences a pronounced enhancement at low invariant $\pi\pi$ masses - as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar $\pi^0\pi^0$ channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. $\Delta\Delta$ calculations give a good description of the data, if a boundstate condition is imposed for the intermediate $\Delta\Delta$ system.
Published