# SPIN 2018

9-14 September 2018
University of Ferrara
Europe/Rome timezone
23RD INTERNATIONAL SPIN SYMPOSIUM

## Recent results in the deuteron break-up with high momentum transfer at COSY

10 Sep 2018, 17:20
20m

### A8

Parallel Sessions Spin Physics in Nuclear Reactions and Nuclei

### 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)

 Slides