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HK: Fachverband Hadronen und Kerne

HK 32: Few-body physics

HK 32.1: Gruppenbericht

Dienstag, 17. März 2009, 14:00–14:30, H-ZO 100

Dynamics of 1S0 diproton formation in pp- and pd-collisions — •Yuriy Uzikov — JINR, LNP, Dubna, Russia

Quasi-binary reactions AB→ {pp}_sC with formation of a proton pair at small excitation energy E_pp=0−3 MeV, i.e. the ¹S₀ diproton {pp}_s, at high transferred momenta can give more definite information on short-range NN-dynamics, as compared to very similar (in kinematics) reactions AB→ dC with the final deuteron d. The reason is that the contribution of non-short range mechanisms related to excitation of the Δ-isobars in intermediate states is expected to be strongly suppressed for the AB→ {pp}_sC reactions as compared to AB→ dC due to isospin symmetry and conservation of angular momentum and parity. In contrast to the expected suppression of the Δ(1232), the cross sections of the reactions pp→ {pp}_sπ⁰ and pp→ {pp}_sγ recently measured at ANKE-COSY in forward direction in the GeV region demonstrate prominent peaks in the Δ-isobar region. This observation would mean that the exected short-range effects (like high momentum component of the NN-wave function) are actually rather week in the reactions with the diproton. Calculations of the differential cross sections of the reactions pd→ {pp}_sn, pp→ {pp}_sπ⁰ and pp→ {pp}_sγ are performed within the one-pion exchange model and are found to be in qualitative agreement with the ANKE-COSY data.

Supported by the DFG grant N⁰ GZ:436 RUS 113/956/0-1