Prospects for the measurement of the W-boson transverse momentum with a low pileup data sample at $\sqrt{s} = 13$ TeV with the ATLAS detector

The imperfect knowledge of the $W$-boson transverse momentum ($p_T^W$) distribution is likely to be the limiting factor for future measurements of the $W$-boson mass at the Large Hadron Collider. This note discusses the prospects for a precise measurement of the $W$-boson transverse momentum distribution using data collected with a low number of additional inelastic proton-proton collisions in the same bunch crossing. Such a sample provides $W$-boson events produced in a clean environment with an improved resolution of the momentum of the system of particles recoiling against the $W$-boson, which is used to measure $p_T^W$. Approximately 300 pb$^{-1}$ of integrated luminosity collected at $\sqrt{s} = 13$ TeV would provide the potential for measuring the inclusive distribution of $p_T^W$ with a relative uncertainty of about 1% in the low-$p_T^W$ range. This would open prospects for a significant improvement on the measurement of the $W$-boson mass with the ATLAS detector.