ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2010, vol. 684, p. 110-113
Exclusive measurements of p p → d π+ π0: Double-pionic fusion without ABC effect
Exclusive measurements of the reaction p p → d π+ π0 have been carried out at Tp = 1.1 GeV at the CELSIUS storage ring using the WASA detector. The isovector π+ π0 channel exhibits no enhancement at low invariant ππ masses, i.e. no ABC effect. Therefore this most basic isovector double-pionic fusion reaction qualifies as an ideal test case for the conventional t-channel ΔΔ excitation process. Indeed, the obtained differential distributions reveal the conventional t-channel ΔΔ mechanism as the appropriate reaction process, which also accounts for the observed energy dependence of the total cross section. © 2010 Elsevier B.V. All rights reserved.