Unparticle effects in photon-photon scattering

TL;DR

This paper investigates how unparticles can induce tree-level photon-photon scattering, potentially leading to observable effects that surpass standard model predictions, due to unique phase interference and larger cross sections.

Contribution

It introduces a novel mechanism for photon-photon scattering via unparticles, highlighting the impact of CP-conserving phases and demonstrating potential for significantly enhanced cross sections.

Findings

Unparticle exchange can produce larger cross sections than the standard model.

Interference effects due to the unparticle phase significantly affect the scattering cross section.

The phase xp(-i d_ \u00a0") influences the interference patterns in scattering.

Abstract

Elastic photon-photon scattering can only occur via loop diagrams in the standard model and is naturally suppressed. Unparticle can induce tree-level photon-photon scattering through the operator F_{\mu\nu} F^{\mu\nu} O_\U for spin-0 unparticle or F_{\mu\alpha} F^{\alpha}_{\nu} O^{\mu\nu}_\U for spin-2 unparticle. Due to the peculiar CP-conserving phase \exp(-i d_\U \pi) associated with the s-channel unparticle propagator, its interference effects with the t- and u-channels on the total cross section and the angular distribution are found to be some significance. In addition, we show that the cross sections via unparticle exchange can be substantially larger than the standard model contribution.