# Electroweak corrections to $e^+e^-\to\gamma\gamma$ as a luminosity process at FCC-ee

## TL;DR

This paper evaluates the electroweak corrections to the process $e^+e^- o \gamma\gamma$ for luminosity measurement at FCC-ee, analyzing higher-order effects and uncertainties to improve theoretical precision.

## Contribution

It provides a detailed phenomenological analysis of electroweak and QED corrections, including higher-order effects, for the luminosity process at future electron-positron colliders.

## Key findings

- Electroweak corrections significantly affect the process at FCC-ee energies.
- Higher-order photon radiation and loop corrections impact theoretical accuracy.
- Uncertainties from hadronic vacuum polarization are estimated.

## Abstract

We consider large-angle two photon production in $e^+ e^-$ annihilation as a possible process to monitor the luminosity of a future $e^+ e^-$ circular collider (FCC-ee). We review and assess the status of the theoretical accuracy by performing a detailed phenomenological study of next-to-leading order electroweak corrections and leading logarithmic QED contributions due to multiple photon radiation. We also estimate the impact of photonic and fermion-loop corrections at next-to-next-to-leading order and the uncertainty induced by the hadronic contribution to the vacuum polarization. Possible perspectives to address the target theoretical accuracy are briefly discussed.