Author/Authors :
J. Johanson، نويسنده , , R. Bilger، نويسنده , , W. Brodowski، نويسنده , , H. Calen، نويسنده , , H. Clement، نويسنده , , C. Ekstrom، نويسنده , , K. Fransson، نويسنده , , J. Greiff، نويسنده , , L. Gustafsson، نويسنده , , S. Haggstrom، نويسنده , , B. Hoistad، نويسنده , , A. Johansson and C. Dixelius، نويسنده , , T. Johansson، نويسنده , , A. Khoukaz and W. Oelert، نويسنده , , I. Koch، نويسنده , , S. Kullander، نويسنده , , A. Kupsc، نويسنده , , P. Marciniewski، نويسنده , , B. Morosov، نويسنده , , W. Oelert، نويسنده , , et al.، نويسنده ,
Abstract :
Two-pion production reactions in proton–proton collisions have been studied using the PROMICE/ WASA detector and an internal cluster gas-jet target at the CELSIUS storage ring in Uppsala. The total cross sections for the pp→ppπ+π−, pp→ppπ0π0 and the pp→pnπ0π+ reactions are presented at beam energies ranging from 650 to 775 MeV. An isospin analysis of the amplitudes involved in these three reactions indicates that the excitation of the N∗(1440) followed by direct two pion emission can be the most important amplitude when allowed. However, large contributions from other production mechanisms must also be prevalent to explain the large pp→pnπ0π+ cross section. The data are compared to an extensive model including non-resonant as well as resonant production via N∗ and Δ excitation.
Keywords :
Nuclear reactions , View the MathML source , (p , (p , p?0?+) , E=650–775 MeV , Measured , ? , ?(?) , deduced , reaction mechanism features , Comparison with model predictions , p2?0)
