BabaYaga@NLO at present and future $e^+e^-$ colliders. Celebrating 25 years of BabaYaga

TL;DR

This work surveys the BabaYaga@NLO framework, a QED parton shower matched to fixed-order calculations, designed to deliver high-precision radiative corrections for e+e- colliders across low and high energies. By employing a Monte Carlo solution to the DGLAP equations and an NLOPS matching scheme, BabaYaga@NLO achieves sub-per-mille to sub-percent accuracy for key luminosity processes and exclusive hadronic channels, with applications at flavour factories and plans for future machines like FCC-ee. The paper discusses the theoretical formulation, accuracy assessments, and phenomenological results, including luminosity calibrations, the pion form factor, and potential NP effects in luminosity observables, highlighting current achievements and future developments such as NNLO QED corrections and extended radiative channels. These developments are pivotal for precision SM tests and for constraining hadronic contributions to aμ, as collider luminosities and cross sections reach unprecedented levels of accuracy. The work thus provides a comprehensive blueprint for next-generation QED radiative-correction tools with broad relevance to collider phenomenology and SM precision measurements.

Abstract

Precise QED radiative corrections for low- and high-energy electron-positron colliders are essential for accurate simulations of luminosity processes and precision tests of the Standard Model. We review the historical formulation and the recent developments of the BabaYaga@NLO event generator, which implements a QED Parton Shower matched with fixed-order calculations. We discuss the theoretical formulation of the code, as well as the assessment of its theoretical accuracy. Applications at low- and high-energy $e^+e^-$ colliders are presented, including latest result, together with the perspectives for future improvements, in view of the demanding precision requirements of future machines at the intensity frontier.