ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2006, vol. 637, p. 223-228
Exclusive measurements of p d → multiscripts(He, prescripts(), mml:none(), 3) π π: The ABC effect revisited
Exclusive measurements of the reactions p d → multiscripts(He, prescripts(), mml:none(), 3) π+ π- and p d → multiscripts(He, prescripts(), mml:none(), 3) π0 π0 have been carried out at Tp = 0.893 GeV at the CELSIUS storage ring using the WASA detector. The π+ π- channel evidences a pronounced enhancement at low invariant ππ masses-as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar π0 π0 channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. ΔΔ calculations give a good description of the data, if a boundstate condition is imposed for the intermediate ΔΔ system. © 2006 Elsevier B.V. All rights reserved.