Photon-photon scattering at the photon linear collider

Abstract

Photon-photon scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to W boson loops are presented. It is shown that photon-photon scattering should be easily observable at PLC and separation of the W loop contribution (which dominates at high energies) will be possible at e + e − c.m. energy of 500 GeV or higher.

Light-by-light scattering with intact protons at the LHC: from standard model to new physics

“…[28] and for vector bosons in ref. [6]. Next-to-leading order corrections from QED and QCD are found to be negligible in [37].…”

“…These loops have been computed in refs. [6,[26][27][28]. We collect explicit expressions in appendix A.…”

“…In this appendix we collect for completeness the expressions for the on-shell four-photon amplitudes generated from heavy spin-1/2 and spin-1 states [6,28]. We also compute various kinematical limits.…”

“…(3.11) and we have defined the shorthand (z) ≡ log(−1/4z) = − log(−4z − i ). The vector-loop induced amplitudes on the other hand show a logarithmic divergence [6,45].…”

“…One should notice that, at the LHC, typical di-photon energies are JHEP02(2015)165 much larger than the masses of these particles. However, while the fermion loop amplitudes approach constants at high energies, the W loop amplitude grows logarithmically [6]. It is therefore the main SM contribution to light-by-light scattering at the LHC whereas it is rarely included in the background simulations.…”