Speaker
Dr
Sergey Dymov
(INFN)
Description
The hadron reactions with the production of a diproton final state, which is a proton pair $\{pp\}_s$
with small excitation energy, have been studied extensively at ANKE-COSY.
These included the break-up process $pd\to \{pp\}_sn$ at high and low momentum transfer,
the $pN\to\{pp\}_s\pi$ one pion production, the $pp\to\{pp\}_s\gamma$ reaction and study of
the ABC effect in the $pp\to\{pp\}_s\pi\pi$ reaction. The low excitation energy ensures
the final $pp$-pair to be in the $^1S_0$ state, thus reducing the number of the partial
waves accessible and simplifying the theoretical description of the process.
The hard break-up process $pd\to \{pp\}_sn$ in the colinear kinematics has been studied
at ANKE in the energy range 0.5-2.0 GeV, where the main reaction mechanisms are the one nucleon
exchange (ONE), $\Delta$-excitation and the single scattering (SS). Selection of a diproton
in the final state suppresses the $\Delta$ mechanism, allowing one to probe the
deuteron structure at short distances. The obtained results, that included the
differential cross-section and the vector analysing power, were compared to the model
predictions produced with several modern $NN$-potentials.
Recently, this study was complemented by the data on the cross section and $A_y$ at 353 MeV,
where one expects the dominance of ONE mechanism, what provides an accurate test of the ONE+$\Delta$+SS
model. These results, analysed together with the ANKE data on the $pn\to \{pp\}_s\pi^-$
and $pp\to \{pp\}_s\pi^0$ reactions, previously extracted at the same energy, may solve
the existing ambiguity in the partial wave analysis of the pion production processes.
Primary author
Dr
Sergey Dymov
(INFN)
