Radiative Corrections to the Electron Compton Scattering Cross Section

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Radiative Corrections to the Electron Compton
Scattering Cross Section

• Liping Gan
• University of North Carolina Wilmington
• June 23, 2006

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Single Compton Scattering
Cross section is first calculated by Klein and
Nishina in 1929
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Virtual-Photon Radiative Correction

• Calculated by Brown and Feynman in 1952
• Contribution to the measurement result is
  independent of experimental setup.

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Double Compton scattering with one soft photon
Contributions to the measurement is independent
of the experimental setup and analysis
procedures.
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Double Compton scatteringwith one hard photon

• Contributions to the measurement depend on the
  experimental setup and analysis procedures. There
  are two cases in our experiment
• Case (a), Unsymmetrical photon pair with an
  undetected photons energy within the HYCAL
  energy resolution.
• Case (b), Both scattering photons have relatively
  large energies, however, they hit on the HYCAL
  with a small opening angle which are
  misidentified as a single cluster by HYCAL.

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Calculation based on the Work of Meister and
Yennie

• Keep up to logarithmic order.
• Consider external current only.
• Exclude the case (b) in the double Compton
  contribution.
• Estimated error is at 2.

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Work in Process

• Using high-energy approximations, and neglect
  terms of the order of 1/E?.
• Complete calculation which includes both case (a)
  and (b) in double Compton scattering
• The result will be available within a week.
• Error bars should be lt1

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Summary

• Current experimental values are in good agreement
  with the theoretic prediction.
• Further improvement on the theoretic calculation
  at lt1 level will provide us a excellent probe to
  understand the systematic errors for the p0 data
  analysis.
• This result is the first precision measurement on
  Compton scattering at a few GeV energy range.