/ Experiment-Nucl arXiv:1007.0405


$\Delta \Delta$ Excitation in Proton-Proton Induced $\pi^0\pi^0$ Production


Skorodko, T. (Tubingen U.) ; Bashkanov, M. (Tubingen U.) ; Bogoslawsky, D. (Dubna, JINR) ; Calen, H. (Uppsala U.) ; Clement, H. (Tubingen U.) ; Doroshkevich, E. (Tubingen U.) ; Demiroers, L. (Hamburg U.) ; Ekstrom, C. (Uppsala U.) ; Fransson, K. (Uppsala U.) ; Gustafsson, L. (Uppsala U.) ; Hoistad, B. (Uppsala U.) ; Ivanov, G. (Dubna, JINR) ; Jacewicz, M. (Uppsala U.) ; Jiganov, E. (Dubna, JINR) ; Johansson, T. (Uppsala U.) ; Khakimova, O. (Tubingen U.) ; Keleta, S. (Uppsala U.) ; Koch, I. (Uppsala U.) ; Kren, F. (Tubingen U.) ; Kullander, S. (Uppsala U.) ; Kupsc, A. (Uppsala U.) ; Marciniewski, P. (Uppsala U.) ; Meier, R. (Tubingen U.) ; Morosov, B. (Dubna, JINR) ; Pauly, C. (Julich, Forschungszentrum) ; Petren, H. (Uppsala U.) ; Petukhov, Y. (Dubna, JINR) ; Povtorejko, A. (Dubna, JINR) ; Ruber, R.J.M.Y. (Uppsala U.) ; Schonning, K. (Uppsala U.) ; Scobel, W. (Hamburg U.) ; Shwartz, B. (Novosibirsk, IYF) ; Stepaniak, J. (Lodz, IPJ) ; Thorngren-Engblom, P. (Stockholm U.) ; Tikhomirov, V. (Dubna, JINR) ; Wagner, G.J. (Tubingen U.) ; Wolke, M. (Uppsala U.) ; Yamamoto, A. (KEK, Tsukuba) ; Zabierowski, J. (Lodz, IPJ) ; Zlomanczuk, J. (Uppsala U.)

Published in: Phys.Lett.
Year: 2011
Vol.: B695
Page No: 115-123
Pages: 9

Abstract: Exclusive measurements of the $pp \to pp\pi^0\pi^0$ reaction have been performed at CELSIUS/WASA at energies from threshold up to $T_p$ = 1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies $T_p \ge$ 1 GeV, where the $\Delta\Delta$ excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional $t$-channel $\Delta\Delta$ excitation. This holds also for the double-pionic fusion to the quasibound $^2$He. The data are compared to model predictions, which are based on both pion and $\rho$ exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the $\rho$-exchange. A phenomenological modification allowing only a small $\rho$ exchange contribution leads to a quantitative description of the data.

Keyword(s): DeltaDelta excitation ; Two-pion production ; pi-exchange ; rho-exchange

Web-Page: http://durpdg.dur.ac.uk/cgi-hepdata/hepreac/8705178; http://inspirebeta.net/record/860341/files/Mpi0pi0_cutMpp10.png; http://inspirebeta.net/record/860341/files/Mpp_1300.png; http://inspirebeta.net/record/860341/files/Mppi0_cutMpp10.png; http://inspirebeta.net/record/860341/files/THpi0pi0_cutMpp10.png; http://inspirebeta.net/record/860341/files/anke_data_model_1100.png; http://inspirebeta.net/record/860341/files/anke_data_model_1400.png; http://inspirebeta.net/record/860341/files/cosp_1000.png; http://inspirebeta.net/record/860341/files/cosp_1100.png; http://inspirebeta.net/record/860341/files/cosp_1200.png; http://inspirebeta.net/record/860341/files/cosp_1300.png; http://inspirebeta.net/record/860341/files/cospi0_1000.png; http://inspirebeta.net/record/860341/files/cospi0_1100.png; http://inspirebeta.net/record/860341/files/cospi0_1200.png; http://inspirebeta.net/record/860341/files/cospi0_1300.png; http://inspirebeta.net/record/860341/files/delta2pi0_1000.png; http://inspirebeta.net/record/860341/files/delta2pi0_1100.png; http://inspirebeta.net/record/860341/files/delta2pi0_1200.png; http://inspirebeta.net/record/860341/files/delta2pi0_1300.png; http://inspirebeta.net/record/860341/files/jec_1000.png; http://inspirebeta.net/record/860341/files/jec_1100.png; http://inspirebeta.net/record/860341/files/jec_1200.png; http://inspirebeta.net/record/860341/files/jec_1300.png; http://inspirebeta.net/record/860341/files/m2pi0_1000.png; http://inspirebeta.net/record/860341/files/m2pi0_1100.png; http://inspirebeta.net/record/860341/files/m2pi0_1200.png; http://inspirebeta.net/record/860341/files/m2pi0_1300.png; http://inspirebeta.net/record/860341/files/mp2pi0_1000.png; http://inspirebeta.net/record/860341/files/mp2pi0_1100.png; http://inspirebeta.net/record/860341/files/mp2pi0_1200.png; http://inspirebeta.net/record/860341/files/mp2pi0_1300.png; http://inspirebeta.net/record/860341/files/mppi0_1000.png; http://inspirebeta.net/record/860341/files/mppi0_1100.png; http://inspirebeta.net/record/860341/files/mppi0_1200.png; http://inspirebeta.net/record/860341/files/mppi0_1300.png; http://inspirebeta.net/record/860341/files/sum2pi0_1000.png; http://inspirebeta.net/record/860341/files/sum2pi0_1100.png; http://inspirebeta.net/record/860341/files/sum2pi0_1200.png; http://inspirebeta.net/record/860341/files/sum2pi0_1300.png; http://inspirebeta.net/record/860341/files/xtot2pi0.png

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