Exclusive $\omega$ meson muoproduction on transversely polarised protons

Abstract

Exclusive production of $\omega$ mesons was studied at the COMPASS experiment by scattering $160\mathrm{GeV}/c$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured in the range of photon virtuality $1(\mathrm{GeV}/c{)}^2<Q^2<10(\mathrm{GeV}/c{)}^2$, Bjorken scaling variable $0.003<x_{Bj}<0.3$ and transverse momentum squared of the $\omega$ meson $0.05(\mathrm{GeV}/c{)}^2<p_T^2<0.5(\mathrm{GeV}/c{)}^2$. The measured asymmetries are sensitive to the nucleon helicity-flip Generalised Parton Distributions (GPD) $E$ that are related to the orbital angular momentum of quarks, the chiral-odd GPDs $H_T$ that are related to the transversity Parton Distribution Functions, and the sign of the $\pi \omega$ transition form factor. The results are compared to recent calculations of a GPD-based model.

arXiv comment23 pages, 9 figures

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• Nucleon structure from basis light-front quantization
• Helicity-dependent generalized parton distributions for nonzero skewness
• Prospects for quarkonium studies at the high-luminosity LHC
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