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N/A

Spokesperson
Abstract
The ep->e'pρ0 reaction has been measured, using the 5.754 GeV electron beam of Jefferson Lab and the CLAS detector. This represents the largest ever set of data for this reaction in the valence region. Integrated and differential cross sections are presented. The W, Q2 and t dependences of the cross section are compared to theoretical calculations based on t-channel meson-exchange Regge theory on the one hand and on quark handbag diagrams related to Generalized Parton Distributions (GPDs) on the other hand. The Regge approach can describe at the ~30% level most of the features of the present data while the two GPD calculations that are presented in this article which succesfully reproduce the high energy data strongly underestimate the present data. The question is then raised whether this discrepancy originates from an incomplete or inexact way of modelling the GPDs or the associated hard scattering amplitude or whether the GPD formalism is simply inapplicable in this region due to higher-twists contributions, incalculable at present.
Publication
  1. S.A.Morrow, M.Guidal, M.Garcon, J.M.Laget, E.S.Smith, and CLAS Collaboration Exclusive ρ0 electroproduction on the proton at CLAS // Eur.Phys.J.A39,5-31(2009)
Quantities
σ   σL   σT   σTT   σTL   dσ/dt   dσL/dt   dσT/dt   Rρ   dσ/dφ   r0004   r1-104   r111   b   σT + εσL   dσ/dcos(θHSπ+)

Measurements

ID Quantity Beam Target Final state Q2min,
GeV2 		Q2max,
GeV2 		Wmin,
GeV 		Wmax,
GeV
E46M1 σ e p ρ0 p 1.725 5.353 1.88157 2.76629
E46M2 σ e p ρ0 p 1.6 1.9 2.2114 2.76629
E46M3 σ e p ρ0 p 1.9 2.2 2.09055 2.63458
E46M4 σ e p ρ0 p 2.2 2.5 1.99874 2.70454
E46M5 σ e p ρ0 p 2.5 2.8 2.09586 2.58305
E46M6 σ e p ρ0 p 2.8 3.1 1.98752 2.42957
E46M7 σ e p ρ0 p 3.1 3.6 2.08964 2.51033
E46M8 σ e p ρ0 p 3.6 4.1 2.00745 2.40925
E46M9 σ e p ρ0 p 4.1 4.6 1.91371 2.30032
E46M10 σ e p ρ0 p 4.6 5.1 1.99516 1.99516
E46M11 σ e p ρ0 p 5.1 5.6 1.88157 1.88157
E46M12 σ e p ρ0 p 2.35 5.353 1.8 2.0
E46M13 σ e p ρ0 p 2.05 4.35 2.0 2.2
E46M14 σ e p ρ0 p 1.785 4.307 2.2 2.4
E46M15 σ e p ρ0 p 1.752 3.807 2.4 2.6
E46M16 σ e p ρ0 p 1.725 2.32 2.6 2.8
E46M17 dσ/dt e p ρ0 p 1.725 1.725 None None
E46M18 dσ/dt e p ρ0 p 1.752 1.752 None None
E46M19 dσ/dt e p ρ0 p 2.042 2.042 None None
E46M20 dσ/dt e p ρ0 p 2.32 2.32 None None
E46M21 dσ/dt e p ρ0 p 1.785 1.785 None None
E46M22 dσ/dt e p ρ0 p 2.05 2.05 None None
E46M23 dσ/dt e p ρ0 p 2.35 2.35 None None
E46M24 dσ/dt e p ρ0 p 2.639 2.639 None None
E46M25 dσ/dt e p ρ0 p 2.05 2.05 None None
E46M26 dσ/dt e p ρ0 p 2.35 2.35 None None
E46M27 dσ/dt e p ρ0 p 2.65 2.65 None None
E46M28 dσ/dt e p ρ0 p 2.95 2.95 None None
E46M29 dσ/dt e p ρ0 p 3.295 3.295 None None
E46M30 dσ/dt e p ρ0 p 2.35 2.35 None None
E46M31 dσ/dt e p ρ0 p 2.65 2.65 None None
E46M32 dσ/dt e p ρ0 p 2.95 2.95 None None
E46M33 dσ/dt e p ρ0 p 3.35 3.35 None None
E46M34 dσ/dt e p ρ0 p 3.807 3.807 None None
E46M35 dσ/dt e p ρ0 p 2.95 2.95 None None
E46M36 dσ/dt e p ρ0 p 3.35 3.35 None None
E46M37 dσ/dt e p ρ0 p 3.85 3.85 None None
E46M38 dσ/dt e p ρ0 p 4.307 4.307 None None
E46M39 dσ/dt e p ρ0 p 3.85 3.85 None None
E46M40 dσ/dt e p ρ0 p 4.35 4.35 None None
E46M41 dσ/dt e p ρ0 p 4.352 4.352 None None
E46M42 dσ/dt e p ρ0 p 4.85 4.85 None None
E46M43 dσ/dt e p ρ0 p 5.353 5.353 None None
E46M44 b e p ρ0 p 1.6 5.6 1.881573 2.766294
E46M45 dσ/dφ e p ρ0 p 1.725 1.725 None None
E46M46 dσ/dφ e p ρ0 p 1.752 1.752 None None
E46M47 dσ/dφ e p ρ0 p 2.042 2.042 None None
E46M48 dσ/dφ e p ρ0 p 2.32 2.32 None None
E46M49 dσ/dφ e p ρ0 p 1.785 1.785 None None
E46M50 dσ/dφ e p ρ0 p 2.05 2.05 None None
E46M51 dσ/dφ e p ρ0 p 2.35 2.35 None None
E46M52 dσ/dφ e p ρ0 p 2.639 2.639 None None
E46M53 dσ/dφ e p ρ0 p 2.05 2.05 None None
E46M54 dσ/dφ e p ρ0 p 2.35 2.35 None None
E46M55 dσ/dφ e p ρ0 p 2.65 2.65 None None
E46M56 dσ/dφ e p ρ0 p 2.95 2.95 None None
E46M57 dσ/dφ e p ρ0 p 3.295 3.295 None None
E46M58 dσ/dφ e p ρ0 p 2.35 2.35 None None
E46M59 dσ/dφ e p ρ0 p 2.65 2.65 None None
E46M60 dσ/dφ e p ρ0 p 2.95 2.95 None None
E46M61 dσ/dφ e p ρ0 p 3.35 3.35 None None
E46M62 dσ/dφ e p ρ0 p 3.807 3.807 None None
E46M63 dσ/dφ e p ρ0 p 2.95 2.95 None None
E46M64 dσ/dφ e p ρ0 p 3.35 3.35 None None
E46M65 dσ/dφ e p ρ0 p 3.85 3.85 None None
E46M66 dσ/dφ e p ρ0 p 4.307 4.307 None None
E46M67 dσ/dφ e p ρ0 p 3.85 3.85 None None
E46M68 dσ/dφ e p ρ0 p 4.35 4.35 None None
E46M69 dσ/dφ e p ρ0 p 4.352 4.352 None None
E46M70 dσ/dφ e p ρ0 p 4.85 4.85 None None
E46M71 dσ/dφ e p ρ0 p 5.353 5.353 None None
E46M72 σT + εσL e p ρ0 p 1.725 5.353 None None
E46M73 σT + εσL e p ρ0 p 1.725 1.725 None None
E46M74 σT + εσL e p ρ0 p 1.752 2.32 None None
E46M75 σT + εσL e p ρ0 p 1.785 2.639 None None
E46M76 σT + εσL e p ρ0 p 2.05 3.295 None None
E46M77 σT + εσL e p ρ0 p 2.35 3.807 None None
E46M78 σT + εσL e p ρ0 p 2.95 4.307 None None
E46M79 σT + εσL e p ρ0 p 3.85 4.35 None None
E46M80 σT + εσL e p ρ0 p 4.352 4.85 None None
E46M81 σT + εσL e p ρ0 p 5.353 5.353 None None
E46M82 σTT e p ρ0 p 1.725 5.353 None None
E46M83 σTT e p ρ0 p 1.725 1.725 None None
E46M84 σTT e p ρ0 p 1.752 2.32 None None
E46M85 σTT e p ρ0 p 1.785 2.639 None None
E46M86 σTT e p ρ0 p 2.05 3.295 None None
E46M87 σTT e p ρ0 p 2.35 3.807 None None
E46M88 σTT e p ρ0 p 2.95 4.307 None None
E46M89 σTT e p ρ0 p 3.85 4.35 None None
E46M90 σTT e p ρ0 p 4.352 4.85 None None
E46M91 σTT e p ρ0 p 5.353 5.353 None None
E46M92 σTL e p ρ0 p 1.725 5.353 None None
E46M93 σTL e p ρ0 p 1.725 1.725 None None
E46M94 σTL e p ρ0 p 1.752 2.32 None None
E46M95 σTL e p ρ0 p 1.785 2.639 None None
E46M96 σTL e p ρ0 p 2.05 3.295 None None
E46M97 σTL e p ρ0 p 2.35 3.807 None None
E46M98 σTL e p ρ0 p 2.95 4.307 None None
E46M99 σTL e p ρ0 p 3.85 4.35 None None
E46M100 σTL e p ρ0 p 4.352 4.85 None None
Created in SINP MSU, CLAS Collaboration