Spin density matrix elements in exclusive ω meson muoproduction

0549445 - ÚPT 2022 RIV DE eng J - Článek v odborném periodiku
Alexeev, G. D. - Alexeev, M. G. - Amoroso, A. - Andrieux, V. - Anosov, V. - Antoshkin, A. - Augsten, K. - Augustyniak, W. - Azevedo, C. D. R. - Badełek, B. - Balestra, F. - Ball, M. - Barth, J. - Beck, R. - Bedfer, Y. - Antequera, J. B. - Bernhard, J. - Bodlák, M. - Bradamante, F. - Bressan, A. - Burtsev, V. E. - Chang, W.-C. - Chatterjee, C. - Chiosso, M. - Chumakov, A. G. - Chung, S.-U. - Cicuttin, A. - Correia, P. M. M. - Crespo, M. L. - D'Ago, D. - Srnka, Aleš … celkem 201 autorů
Spin density matrix elements in exclusive ω meson muoproduction.
1434-6044. E-ISSN 1434-6052. European Physical Journal C. Roč. 81, č. 2 (2021), č. článku 126. ISSN 1434-6044. E-ISSN 1434-6052
Institucionální podpora: RVO:68081731
Klíčová slova: meson muoproduction * liquid hydrogen target * generalised parton distributions
Obor OECD: Particles and field physics
Impakt faktor: 4.994, rok: 2021
Způsob publikování: Open access
https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-020-08740-y

We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive omega meson muoproduction on the proton at COMPASS using 160 GeV/c polarised mu(+) and mu(-) beams impinging on a liquid hydrogen target. The measurement covers the range 5.0 GeV/c(2) < W < 17.0 GeV/c(2), with the average kinematics Q(2)= 2.1 (GeV/c)(2), W =7.6 GeV/c(2), and < p(T)(2)>=0.16 (GeV/c)(2). Here, Q(2) denotes the virtuality of the exchanged photon, W the mass of the final hadronic system and p(T) the transverse momentum of the omega 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 (gamma(*)(T)> V-L) 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 omega production.
Trvalý link: http://hdl.handle.net/11104/0325474