Abstract
Exclusive production of ρ0 mesons was studied at the COMPASS experiment by scattering 160 GeV/c muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured as a function of Q2, xBj, or pT2. The sinϕS asymmetry is found to be −0.019±0.008(stat.)±0.003(syst.). All other asymmetries are also found to be of small magnitude and consistent with zero within experimental uncertainties. Very recent calculations using a GPD-based model agree well with the present results. The data is interpreted as evidence for the existence of chiral-odd, transverse generalized parton distributions.
Highlights
Introduction and formalismHard exclusive meson leptoproduction on nucleons (HEMP) can be described in the framework of perturbative Quantum Chromodynamics
For incoming longitudinal virtual photons, collinear factorisation holds for the HEMP process amplitude [1, 2]
It factorises into a hard part that is calculable in perturbative Quantum Chromodynamics (pQCD) and a soft part that contains generalised parton distributions (GPDs) [3,4,5] and the meson distribution amplitude
Summary
Introduction and formalismHard exclusive meson leptoproduction on nucleons (HEMP) can be described in the framework of perturbative Quantum Chromodynamics (pQCD). Phenomenological GPD-based model calculations agree well with the data and interpret the result as evidence for the existence of chiral-odd, transverse generalised parton distributions. It factorises into a hard part that is calculable in pQCD and a soft part that contains generalised parton distributions (GPDs) [3,4,5] and the meson distribution amplitude.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
