1. |
- Bargholtz, Chr., et al.
(author)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
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Journal article (peer-reviewed)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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2. |
- Skorodko, T., et al.
(author)
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Delta Delta excitation in proton-proton induced pi(0)pi(0) production
- 2011
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 695:1-4, s. 115-123
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Journal article (peer-reviewed)abstract
- Exclusive measurements of the pp -> 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 >= 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 He-2. The data are compared to model predictions, which are based on both pi- 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.
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3. |
- Skorodko, T., et al.
(author)
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THE pp -> pp pi(0)pi(0) REACTION AND ITS LIMITING CASE, FUSION TO QUASI-BOUND He-2, IN SEARCH OF THE ABC EFFECT
- 2011
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In: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 26:3-4, s. 702-704
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Journal article (peer-reviewed)abstract
- The pi(0)pi(0) production in pp-collisions has been investigated in exclusive and kinematically complete measurements from threshold up to T-p = 1.4 GeV. For incident energies T-p > 1 GeV, i.e. in the region beyond the Roper excitation, the Delta Delta excitation process takes over. The data are well explained by the t-channel Delta Delta process dominated by pion exchange. There is no low-mass enhancement (ABC effect) in the pi(0)pi(0)-invariant mass distribution beyond that given by the conventional t-channel Delta Delta process. This is also true for the limiting case, where the protons are in the quasi-bound He-2 state.
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