Spin density matrix elements in exclusive ω meson muoproduction
Abstract: We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive meson muoproduction on the proton at COMPASS using 160 GeV/c polarised and beams impinging on a liquid hydrogen target. The measurement covers the range 5.0 GeV/ 17.0 GeV/, with the average kinematics 2.1 (GeV/c), GeV/, and (GeV/c). Here, denotes the virtuality of the exchanged photon, W the mass of the final hadronic system and the transverse momentum of the 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 () indicate a violation of s-channel helicity conservation. Additionally, we observe a sizeable contribution of unnatural-parity-exchange (UPE) transitions that decreases with increasing W. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow to evaluate in a model-dependent way the contribution of UPE transitions and assess the role of parton helicity-flip GPDs in exclusive production
- Standort
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Deutsche Nationalbibliothek Frankfurt am Main
- Umfang
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Online-Ressource
- Sprache
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Englisch
- Anmerkungen
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The European physical journal. C. - 81, 2 (2021) , 126, ISSN: 1434-6052
- Ereignis
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Veröffentlichung
- (wo)
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Freiburg
- (wer)
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Universität
- (wann)
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2024
- Urheber
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Alexeev, Gennady
Fischer, Horst
Gorzellik, Matthias
Herrmann, Florian
Jörg, Philipp
Mallot, Gerhard Konrad
Regali, Christopher Ralph
Szameitat, Tobias
Ziembicki, Marcin
COMPASS Collaboration, [Study group]
- DOI
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10.1140/epjc/s10052-020-08740-y
- URN
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urn:nbn:de:bsz:25-freidok-2475540
- Rechteinformation
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Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
- Letzte Aktualisierung
- 14.08.2025, 10:58 MESZ
Datenpartner
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Beteiligte
- Alexeev, Gennady
- Fischer, Horst
- Gorzellik, Matthias
- Herrmann, Florian
- Jörg, Philipp
- Mallot, Gerhard Konrad
- Regali, Christopher Ralph
- Szameitat, Tobias
- Ziembicki, Marcin
- COMPASS Collaboration, [Study group]
- Universität
Entstanden
- 2024