Two-pion production in proton–proton collisions — experimental total cross sections and their isospin decomposition

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• 作者：T. Skorodko ; M. Bashkanov ; D. Bogoslawsky ; H. Calé ; n ; H. Clement ; E. Doroshkevich ; L. Demiroers ; C. Ekströ ; m ; K. Fransson ; L. Gustafsson ; B. Hö ; istad ; G. Ivanov ; M. Jacewicz ; E. Jiganov ; T
• 刊名：Physics Letters B
• 出版年：2009
• 出版时间：10 August 2009
• 年：2009
• 卷：679
• 期：1
• 页码：30-35
• 全文大小：248 K

文摘

The two-pion production in pp-collisions has been investigated at CELSIUS in exclusive measurements from threshold up to T_p=1.36 GeV. Total and differential cross sections have been obtained for the channels pnπ⁺π⁰, ppπ⁺π⁻, ppπ⁰π⁰ and also nnπ⁺π⁺. For intermediate incident energies T_p>1 GeV, i.e. in the region which is beyond the Roper excitation but at the onset of ΔΔ excitation, the total ppπ⁰π⁰ cross section falls behind theoretical predictions by as much as an order of magnitude near 1.2 GeV, whereas the nnπ⁺π⁺ cross section is a factor of five larger than predicted. An isospin decomposition of the total cross sections exhibits a s-channel-like energy dependence in the region of the Roper excitation as well as a significant contribution of an isospin 3/2 resonance other than the Δ(1232). As possible candidates the Δ(1600) and the Δ(1700) are discussed.