A closer look at the beam-beam processes at ILC and CLIC

TL;DR

This paper investigates the impact of strong electromagnetic fields during bunch collisions at ILC and CLIC colliders, focusing on how these fields influence higher order processes and transition rates, which are crucial for precision physics.

Contribution

It introduces a method to calculate the effect of strong bunch fields on transition rates using exact wavefunctions and Furry interaction, revealing significant variations near threshold energies.

Findings

Strong bunch fields significantly affect transition rates.

A multiplicative factor to coupling constants was derived.

Variations are especially notable near threshold energies.

Abstract

The strength of the electromagnetic fields in the bunch collision at a linear collider will have a significant effect, yielding large numbers of beamstrahlung photons and associated coherent pair production. These effects are limited in the proposed ILC beam parameters which limit the strength of the bunch field to $\Upsilon_{\text{ave}}=0.27$. The CLIC 3 Tev design by comparison has a $\Upsilon_{\text{ave}}=3.34$ yielding huge number of coherent pairs. In terms of the precision physics programs of these proposed colliders there is an imperative to investigate the effect of the strong bunch fields on higher order processes. From the exact wavefunctions used in the calculation of transition rates within the Furry interaction picture, and using appropriate simplifications, a multiplicative factor to the coupling constants was obtained. This indicates a significant variation to the transition rate near threshold energies. Further studies are in progress to calculate the exact effect on expected observables.