Prospects for measuring the W boson mass with LHCb

Precision electroweak tests are a powerful probe of physics beyond the Standard Model, but the sensitivity is limited by the precision with which the W boson mass has been measured. The Parton Distribution Function (PDF) uncertainties are a potential limitation for measurements of the W mass with LHC data. It has recently been suggested that a new measurement of the W boson mass by LHCb would complement measurements by ATLAS and CMS. While the measurement of the W mass by LHCb would also be susceptible to uncertainties in the PDFs, 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 report on a new study on the mechanism driving the PDF uncertainty in the LHCb measurement of the W mass, and propose an approach which should reduce this uncertainty by roughly a factor of two using LHCb Run 2 data.