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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
E46M201 dσL/dt e p ρ0 p 4.307 4.307 None None
E46M202 dσL/dt e p ρ0 p 3.85 3.85 None None
E46M203 dσL/dt e p ρ0 p 4.35 4.35 None None
E46M204 dσL/dt e p ρ0 p 4.352 4.352 None None
E46M205 dσL/dt e p ρ0 p 4.85 4.85 None None
E46M206 dσL/dt e p ρ0 p 5.353 5.353 None None
E46M207 σL e p ρ0 p 1.725 5.353 None None
E46M208 σL e p ρ0 p 1.725 1.725 None None
E46M209 σL e p ρ0 p 1.752 2.32 None None
E46M210 σL e p ρ0 p 1.785 2.639 None None
E46M211 σL e p ρ0 p 2.05 3.295 None None
E46M212 σL e p ρ0 p 2.35 3.35 None None
E46M213 σL e p ρ0 p 2.95 3.85 None None
E46M214 σL e p ρ0 p 3.85 4.35 None None
E46M215 σL e p ρ0 p 4.352 4.85 None None
E46M216 σL e p ρ0 p 5.353 5.353 None None
E46M217 σT e p ρ0 p 1.725 5.353 1.88157 2.76629
E46M218 σT e p ρ0 p 1.6 1.9 2.2114 2.76629
E46M219 σT e p ρ0 p 1.9 2.2 2.09055 2.63458
E46M220 σT e p ρ0 p 2.2 2.5 1.99874 2.70454
E46M221 σT e p ρ0 p 2.5 2.8 2.09586 2.58305
E46M222 σT e p ρ0 p 2.8 3.1 1.98752 2.42957
E46M223 σT e p ρ0 p 3.1 3.6 2.08964 2.51033
E46M224 σT e p ρ0 p 3.6 4.1 2.00745 2.21065
E46M225 σT e p ρ0 p 4.1 4.6 1.91371 2.10688
E46M226 σT e p ρ0 p 4.6 5.1 1.99516 1.99516
E46M227 σT e p ρ0 p 5.1 5.6 1.88157 1.88157
E46M228 dσT/dt e p ρ0 p 1.725 1.725 None None
E46M229 dσT/dt e p ρ0 p 1.752 1.752 None None
E46M230 dσT/dt e p ρ0 p 2.042 2.042 None None
E46M231 dσT/dt e p ρ0 p 2.32 2.32 None None
E46M232 dσT/dt e p ρ0 p 1.785 1.785 None None
E46M233 dσT/dt e p ρ0 p 2.05 2.05 None None
E46M234 dσT/dt e p ρ0 p 2.35 2.35 None None
E46M235 dσT/dt e p ρ0 p 2.639 2.639 None None
E46M236 dσT/dt e p ρ0 p 2.05 2.05 None None
E46M237 dσT/dt e p ρ0 p 2.35 2.35 None None
E46M238 dσT/dt e p ρ0 p 2.65 2.65 None None
E46M239 dσT/dt e p ρ0 p 2.95 2.95 None None
E46M240 dσT/dt e p ρ0 p 3.295 3.295 None None
E46M241 dσT/dt e p ρ0 p 2.35 2.35 None None
E46M242 dσT/dt e p ρ0 p 2.65 2.65 None None
E46M243 dσT/dt e p ρ0 p 2.95 2.95 None None
E46M244 dσT/dt e p ρ0 p 3.35 3.35 None None
E46M245 dσT/dt e p ρ0 p 3.807 3.807 None None
E46M246 dσT/dt e p ρ0 p 2.95 2.95 None None
E46M247 dσT/dt e p ρ0 p 3.35 3.35 None None
E46M248 dσT/dt e p ρ0 p 3.85 3.85 None None
E46M249 dσT/dt e p ρ0 p 4.307 4.307 None None
E46M250 dσT/dt e p ρ0 p 3.85 3.85 None None
E46M251 dσT/dt e p ρ0 p 4.35 4.35 None None
E46M252 dσT/dt e p ρ0 p 4.352 4.352 None None
E46M253 dσT/dt e p ρ0 p 4.85 4.85 None None
E46M254 dσT/dt e p ρ0 p 5.353 5.353 None None
Created in SINP MSU, CLAS Collaboration