Bonn 2010 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Hadronenstruktur und -spektroskopie V

HK 25.2: Talk

Tuesday, March 16, 2010, 16:45–17:00, HG III

Study of the pd->pdX reaction in the ABC-effect region — •Tatiana Azaryan — JINR, Dubna, Russia

The ABC effect which is a low-mass enhancement in the pion-pion invariant mass spectrum, first observed by Abashian, Booth and Crow, is still not clearly understood.

The reaction p+d→ p+d+X was investigated at COSY-ANKE, Juelich at four proton beam energies: 0.8, 1.1, 1.4 and 2.0 GeV. Here we present the results obtained for two-pion production in a region traditionally referred to the ABC region. We observe a strong enhancement of the two-pion invariant mass spectrum close to the production threshold. In our measurements the final proton and deuteron were detected, and the 4-momentum of the unobserved particle(s) was reconstructed. In this inclusive reaction the proton and deuteron momenta have been measured at angles close to 0 degree (from 0 up to 15 degree). One should note that the kinematical conditions in our case are very different from other studies of the ABC-effect.