Spin Density Matrix Elements in Exclusive rho^0 Electroproduction on 1H and 2H Targets at 27.5 GeV Beam Energy

Abstract

Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive rho^0 electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1 GeV^2 < Q^2 < 7 GeV^2, 3.0 GeV < W < 6.3 GeV, and -t < 0.4 GeV^2. Within the given experimental uncertainties, a hierarchy of relative sizes of helicity amplitudes is observed. Kinematic dependences of all SDMEs on Q^2 and t are presented, as well as the longitudinal-to-transverse rho^0 electroproduction cross section ratio as a function of Q^2. A small but statistically significant deviation from the hypothesis of s-channel helicity conservation is observed. An indication is seen of a contribution of unnatural-parity-exchange amplitudes; these amplitudes are naturally generated with a quark-exchange mechanism.

41 pages, 20 figures, 16 table; revised version corrects small typos, text clarified on 6 pages, two references added and new data added to figure 20

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Cited by in corpus (21)

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• A phenomenological study of helicity amplitudes of high energy exclusive leptoproduction of the rho meson
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• The pion pole in hard exclusive vector-meson leptoproduction
• Exclusive rho-0 electroproduction on transversely polarized protons
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• Ratios of Helicity Amplitudes for Exclusive rho-0 Electroproduction
• Prospects for quarkonium studies at the high-luminosity LHC
• Status of DVMP, DVCS and GPDs
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• Exclusive $\omega$ meson muoproduction on transversely polarised protons
• Exploring Baryon Resonances with Transition Generalized Parton Distributions: Status and Perspectives
• Contribution of exclusive diffractive processes to the measured azimuthal asymmetries in SIDIS
• Twist-3 contribution to deeply virtual electroproduction of pions
• Anomalous quark-gluon chromomagnetic interaction and high energy $\rho$-meson electroproduction
• Hard exclusive processes: theoretical status
• Generelized Parton Distributions in light meson production
• DVCS at HERMES
• Spin effects in hard exclusive electroproduction of mesons
• Amplitudes ratios in ${\rho }^0$ leptoproductions and GPDs