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

Spin-density matrix elements in hard exclusive muoproduction of $\omega$ mesons at COMPASS

11 Sep 2018, 15:40
30m
A5 (Polo degli Adelardi - Via Adelardi, 33)

A5

Polo degli Adelardi - Via Adelardi, 33

Via Adelardi, 33
Parallel Sessions 3D Structure of the Nucleon: GPDs and Form Factors 3D Structure of the Nucleon: GPDs and Form Factors

Speaker

Dr Bohdan Marianski (National Centre for Nuclear Studies\ Warsaw, Poland\)

Description

Spin density matrix elements (SDMEs) have been determined for exclusive $\omega$ meson production on unpolarized protons, in the COMPASS kinematic region of 1.0 (GeV/$c^2$) $< Q^{2} <$ 10.0 (GeV/$c^2$), 5.0 GeV/$c^2$ $< W < $ 17.0 GeV/$c^2$ and 0.01 (GeV/$c^2$) $= 2.1$~(GeV/$c^2$), $\left< W \right>= 7.6$~GeV/$c^2$ and $\left = 0.16$~(GeV/$c^2$) mean values. The analysis is based on data taken in 2012 with the 160 GeV muon beam and the liquid hydrogen target. Using extracted SDMEs the contribution of unnatural parity exchange amplitudes, the longitudinal-to-transverse cross section ratio, and the hypothesis of s-channel helicity conservation (SCHC) were studied. A sizable contribution of unnatural parity exchange amplitudes is found for the exclusive $\omega$ meson muoproduction, although there is a clear indication of its decrease with increasing W. Certain matrix elements e.g. $ r^{5}_{00}$ corresponding to transition $\gamma^*_T \to V_L$ indicate violation of SCHC in exclusive $\omega $ production.

Primary author

Dr Bohdan Marianski (National Centre for Nuclear Studies\ Warsaw, Poland\)

Presentation Materials