Forward elastic scattering of light on light, $\gamma+\gamma\rightarrow\gamma+\gamma$

M.M. Block; G. Pancheri

doi:doi:10.1007/s10052-002-1019-6

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2024 Impact factor 4.8

Particles and Fields

Eur. Phys. J. C 25, 287-289 (2002)
DOI: 10.1007/s10052-002-01019-6

Forward elastic scattering of light on light, $\gamma+\gamma\rightarrow\gamma+\gamma$

M.M. Block¹ and G. Pancheri²

¹ Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
² INFN-Laboratori Nazionali di Frascati, 00044 Frascati, Italy

(Received: 18 June 2002 / Published online: 9 August 2002 )

Abstract
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 $5\ {\rm GeV}\le \sqrt s\le 130$ GeV, assuming a cross section that rises asymptotically as $\ln^2 s$ . 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 $\rho_{\gamma p}$ [CITE], the $\rho$ value for Compton scattering. Within errors, we find that the three $\rho$ -values in the c.m.s. energy region $5\ {\rm GeV}\le \sqrt s\le 130$ GeV are the same, as predicted by a factorization theorem of Block and Kaidalov [CITE].