Measurements of p(e, e

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Measurements of p(e, ep )n in the ?(1232) and
higher resonances for Q24.9GeV2

• October 12, 2005 _at_ Tallahassee, FL

• Physics Motivation
• Kinematics
• Experiments Analysis Process
• Results
• Cross Section Asymmetry
• Structure functions Photocoupling Amplitude
• Summary

• N 2005 Meeting Kijun Park

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• Physics Motivation

• ?

History of Roper Resonance

• Roper signature has been clearly seen in
• pN and ?N reactions.
• The unresolved low mass of P11(1440)

• Close, Capstick, Simula CQM
• ? N2 radially excited state
• Cano-Gonzalez A system consisting of a hard
  quark core vector meson cloud
• Li-Burkert A hybrid states with q3G
• P11(1440) is a pentaquark state ?

• ?

Various Q2 dependences for transition
form-factors are predicted by different models.
Photocoupling Amplitude
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Single pion Electroproduction

• Kinematics

Kinematic variable

• Unpol. Xsection w/ one-photon exchange approx.

• s-channel

• t-channel

• Study of Resonance to understand Nucleon
  Structure
• Most Studies for N?(1232) and NN(1535) using
  pp0, p? channels
• States with I1/2 couple more to the np than pp0
• Cross Section Asymmetry gives us information on
  resonances in excited states

• Asymmetry

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• E1-6 Data Kinematic Coverage

• Experimental Data

• E1-6 Data (Oct.2001-Jan.2002)
• 5.754GeV polarized e- LH2
• 7M np trigger after MMx cut

WGeV 1.1 1.8 0.02(35)
Q2GeV2 1.72 4.92 Variable(7)
CSCM -1.0 1.0 0.2(10)
PHICM 0. 360.O 15O(24)

• Kinematic
• Bins
• 58,800

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• Cross section vs. PHICM , W

• Cross section as function of f
• _at_ W1.23GeV, CSCM 0.1, Different Q2 bins

• Cross section as function of W
• _at_ CSCM 0.1 , 0.3
• f 67.5 o, 142.5o
• Different Q2 bins

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• Asymmetry vs. PHICM

W1.23GeV, Q22.05GeV2
W1.40GeV, Q22.05GeV2
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• Structure Function

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• Structure Function

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• Structure Function

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• Structure Function

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• Photo-coupling Amp.

Light-front calculation
Quark Models

• preliminary

q3G hybrid state
p-2p analysis
p electro- production IM, DR
?electro-, photo- production IM, DR
RPP estimation
GWU (VPI) pion photoproduction
This Work
Relativistic Quark Model
Non-relativistic Quark Model
Bonn, DESY, NINA, Jlab(?)
re-analyze the old data MAINZ
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• Photo-coupling Amp.

• preliminary

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• Summary

• Differential Cross Section has been measured
  first time completely over all angular range in
  1.1 lt W lt 1.8GeV at high 1.7 lt Q2 lt 4.9GeV2
• Electron Beam Asymmetry has been measured in same
  kinematic region.
• Measurement of Cross Section and Asymmetry have
  been compared to recent physics models such as
  MAIDs, Sato-Lee, DMT etc.
• sTeLsL , sTT , sLT , sLT / Structure Functions
  have been extracted.
• The Cross Section and Beam Spin Asymmetry are
  fitted to extract the Transition Form Factors and
  compared with present predictions.