Pascalutsa-Vanderhaeghen light-by-light sumrule from photon-photon collisions

Abstract

Light-by-light scattering sumrules based on general field theory principles relate cross-sections with different helicities. In this paper the simplest sumrule is tested for the $I=0$ and $2$ channels for "real" photon-photon collisions. Important contributions come from the long-lived pseudoscalar mesons and from di-meson intermediate states. The latest Amplitude Analysis of $\gamma \gamma \to \pi \pi ,\overline{K}K$ allows this contribution to be evaluated. However, we find that other multi-meson contributions up to 2.5 GeV are required to satisfy the sumrules. While data on three and four pion cross-sections exist, there is no information about their isospin and helicity decomposition. Nevertheless, we show the measured cross-sections are sufficiently large to ensure the sumrules for the helicity differences are likely fulfilled.

13 pages, 1 figure

References in corpus (8)

• Comprehensive Amplitude Analysis of $\gamma \gamma \to {\pi }^{+}{\pi }^{-},{\pi }^0{\pi }^0$ and $\overline{K}K$ below 1.5 GeV
• High statistics study of f_0(980) resonance in gamma gamma --> pi^+ pi^- production
• High-statistics measurement of neutral-pion pair production in two-photon collisions
• High-statistics measurement of neutral-pion pair production in two-photon collisions
• Two photon couplings of the lightest isoscalars from BELLE data
• High-statistics study of neutral-pion pair production in two-photon collisions
• Sum rules for light-by-light scattering
• Measurement of neutral pion pair production in two-photon collisions