Status and accuracy of the Monte Carlo generators for luminosity measurements

TL;DR

This paper reviews the current status and precision of Monte Carlo generators used for luminosity measurements at flavour factories, highlighting their accuracy, validation efforts, and potential for further improvements.

Contribution

It provides a comprehensive assessment of the accuracy of Monte Carlo generators for luminosity, including validation against higher-order QED corrections and discussion of future improvements.

Findings

Current generators achieve about 0.1% accuracy.

Validation against NNLO QED corrections confirms robustness.

Further improvements are possible with recent advances.

Abstract

The status and accuracy of the precision Monte Carlo generators used for luminosity measurements at flavour factories is reviewed. It is shown that, thanks to a considerable, long-term effort in tuned comparisons between the predictions of independent programs, as well as in the validation of the generators against the presently available calculations of the next-to-next-to-leading order QED corrections to Bhabha scattering, the theoretical accuracy reached by the most precise tools is of about one per mille. This error estimate is valid for realistic experimental cuts, appears to be quite robust and is already sufficient for very accurate luminosity measurements. However, recent progress and possible advances to further improve it are also discussed.