# Extra lepton pair emission corrections to Drell-Yan processes in PHOTOS and SANC

## TL;DR

This paper evaluates the accuracy of PHOTOS and SANC algorithms in simulating lepton pair emissions in Z boson decays, crucial for precise LHC measurements, and discusses their systematic errors and future improvements.

## Contribution

It provides a comparative analysis of PHOTOS and SANC algorithms for lepton pair emission corrections in Drell-Yan processes, with numerical results relevant for LHC precision measurements.

## Key findings

- Pair emissions can be neglected at 0.3% precision level.
- Current algorithms are sufficient for 0.1-0.2% precision.
- Further work needed for 0.1% accuracy.

## Abstract

In the paper we present results for final state emissions of lepton pairs in decays of heavy intermediate states such as Z boson. Short presentations of PHOTOS and SANC algorithms and physics assumptions are given. Numerical distributions of relevance for LHC observables are shown. They are used in discussions of systematic errors in the predictions of pair emissions as implemented in the two programs. Suggestions for the future works are given. Present results confirm, that for the precision of 0.3% level, in simulation of final state the pair emissions can be avoided. For the precision of 0.1-0.2%, the results obtained with the presented programs should be enough. To cross precision tag of 0.1%, the further work is however required.