# Towards a W boson mass measurement with LHCb

## TL;DR

This paper discusses the potential of LHCb to measure the W boson mass at the LHC, highlighting its unique forward rapidity measurements and proposing methods to reduce PDF uncertainties for improved precision.

## Contribution

It introduces a new approach to significantly reduce PDF uncertainties in W mass measurements using LHCb Run 2 data, complementing existing ATLAS and CMS results.

## Key findings

- LHCb can contribute to W mass measurements at forward rapidities.
- A new method could halve the PDF uncertainty in LHCb's W mass measurement.
- Combining LHCb results with ATLAS and CMS can improve overall W mass precision.

## Abstract

LHCb provides unique opportunities to study $W$ and $Z$ boson production at forward rapidities at the LHC. It has recently been suggested that a measurement of the $W$ boson mass by LHCb would complement measurements by ATLAS and CMS. All measurements of the $W$ mass at hadron colliders are subject to PDF uncertainties, but there would be a partial cancellation of the overall PDF uncertainty when the LHCb result is included in an average with measurements by ATLAS and CMS. Here we review measurements of $W$ and $Z$ boson production by LHCb, and report on a new study of the PDF uncertainty on the LHCb measurement of the $W$ mass. The latter study includes the proposal of a new approach that should reduce the PDF uncertainty by roughly a factor of two with LHCb Run 2 data.