| Article | |
| Title | Hard exclusive meson production in muon scattering at COMPASS |
| Author(s) | Sandacz, Andrzej (NCBJ, Warsaw) |
| Collaboration | COMPASS Collaboration |
| Publication | 2022 |
| Number of pages | 7 |
| In: | EPJ Web Conf. 270 (2022) 00006 |
| In: | 10th International Workshop on QCD - Theory and Experiment (QCD@Work 2022), Lecce, Italy, 27 -30 June 2022, pp.00006 |
| DOI | 10.1051/epjconf/202227000006 |
| Subject category | Particle Physics - Experiment |
| Accelerator/Facility, Experiment | CERN SPS ; NA58 |
| Abstract | We report on measurements of hard exclusive muoproduction of ρ0, ω and π0 mesons on the proton at COMPASS using 160 GeV/c polarized μ+ and μ− beams scattering off a liquid hydrogen target. The extracted Spin Density Matrix Elements for vector mesons indicate a violation of s-channel helicity conservation for transitions of transversely polarized virtual photons to longitudinally polarized vector mesons, γT → VL, where V denotes ρ0 or ω meson. Additionally, for ρ0 production we observe a dominant contribution of natural-parity-exchange transitions and a small contribution of unnaturalparity-exchange transitions. On the contrary, the contribution of unnaturalparity-exchange for ω production is significant and it decreases with increasing W, being still non-negligible at the largest W values accessible at COMPASS. Further, we present also the absolute value of the differential cross section for exclusive π0 production and its dependence on squared four-momentum transfer t and azimuthal angle ø between the scattering plane and π0 production plane. The results provide an important input for modeling Generalized Parton Distribution (GPDs), and in particular to constrain chiral-odd (transversity) GPDs. |
| Copyright/License | © 2022-2025 The Authors (License: CC-BY-4.0) |
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