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

• Published in: The European physical journal. C, Particles and fields Vol. 25; no. 2; pp. 287 - 289
• Main Author: MM Block G Pancheri
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01-09-2002
• Subjects: Cross-sections; Elastic scattering; Forward scattering; Scattering amplitude
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1007/s10052-002-1019-6

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].