| Title: |
Spin density matrix elements in exclusive ρ^0 meson muoproduction ; Spin density matrix elements in exclusive [rho]^0 meson muoproduction |
| Authors: |
COMPASS Collaboration, Study group; Fischer, Horst; Gorzellik, Matthias; Mallot, Gerhard K. |
| Source: |
The European physical journal. - 83, 10 (2023) , 924, ISSN: 1434-6052 |
| Publication Year: |
2023 |
| Collection: |
University of Freiburg: FreiDok |
| Description: |
We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive ρ0 meson muoproduction at COMPASS using 160 GeV/c polarised μ + and μ − beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0 GeV/c2 < W < 17.0 GeV/c2, 1.0 (GeV/c)2 < Q2 < 10.0 (GeV/c)2 and 0.01 (GeV/c)2 < p2T < 0.5 (GeV/c)2. Here, W denotes the mass of the final hadronic system, Q2 the virtuality of the exchanged photon, and pT the transverse momentum of the ρ0 meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons (γ ∗ T → VL ) indicate a violation of s-channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive ρ0 production. |
| Document Type: |
article in journal/newspaper |
| File Description: |
pdf |
| Language: |
English |
| Relation: |
https://freidok.uni-freiburg.de/data/254367 |
| DOI: |
10.1140/epjc/s10052-023-11359-4 |
| Availability: |
https://freidok.uni-freiburg.de/data/254367; https://nbn-resolving.org/urn:nbn:de:bsz:25-freidok-2543671; https://doi.org/10.1140/epjc/s10052-023-11359-4; https://freidok.uni-freiburg.de/dnb/download/254367 |
| Rights: |
free |
| Accession Number: |
edsbas.6225C2BC |
| Database: |
BASE |