Forward elastic scattering of light on light, \(\gamma+\gamma\rightarrow\gamma+\gamma\)

  • M.M. Block G. Pancheri
Theoretical Physics


The forward elastic scattering of light on light, i.e., the reaction \(\gamma+\gamma\rightarrow\gamma+\gamma\) in the forward direction, is analyzed utilizing real analytic amplitudes. We calculate \(\rho_{\gamma \gamma}\), the ratio of the real to the imaginary portion of the forward scattering amplitude, by fitting the total \(\gamma \gamma\) cross section data in the high energy region 5 GeV \(\le \sqrt s\le 130\) GeV, assuming a cross section that rises asymptotically as ln2 s. We then compare \(\rho_{\gamma \gamma} to \rho_{nn}\), the ratio of the even portions of the pp and \(\bar pp\) forward scattering amplitudes, as well as to \(\rho_{\gamma p}\) [1], the \(\rho\) value for Compton scattering. Within errors, we find that the three \(\rho\)-values in the c.m.s. energy region 5 GeV\(\le \sqrt s\le\) 130 GeV are the same, as predicted by a factorization theorem of Block and Kaidalov [2].


Energy Region Total Cross Section Elastic Scattering Cross Section Data Forward Direction 
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Copyright information

© Springer-Verlag Berlin Heidelberg / Società Italiana di Fisica 2002

Authors and Affiliations

  • M.M. Block G. Pancheri
    • 1
  1. 1.Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA US

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