# Effect of emission of extra lepton pair for precise measurement of W-boson mass

## TL;DR

This paper investigates the impact of additional lepton pair emissions in Z and W boson decays, providing a semi-analytical calculation and a Monte Carlo program that agree within 5%, aiding precise W-boson mass measurements.

## Contribution

It introduces a semi-analytical method and a Monte Carlo program for modeling lepton pair emissions in heavy boson decays, enhancing precision in W-boson mass measurements.

## Key findings

- Semi-analytical calculation matches PHOTOS MC within 5%.
- Lepton pair emissions significantly affect W-boson mass measurements.
- Future work suggestions are provided.

## Abstract

In the paper we present results for final state emissions of lepton pairs in decays of heavy intermediate states principally of Z boson, but of some importance for the W decays as well. The presented semi-analytical calculation and PHOTOS MC program are in numerical agreement to better than $5\%$ of pair effects. Suggestions for the future works are given.