Towards the W-boson mass measurement with the CMS experiment

The precision measurement of the mass of the W boson ($m_W$) represents an extraordinary tool to test the internal consistency of the Standard Model and probe the existence of new physics. At the LHC, one of the main uncertainties on the $m_W$ measurement arises from PDFs, which determine the production kinematics of the W. The PDF uncertainty can be reduced through the measurement of the helicity and rapidity of W bosons ($h_W$/$Y_W$) produced at the LHC. The measurement of $h_W$/$Y_W$ is carried out using $W\to \ell\nu$ events, and exploits the correlation between the helicity of the W boson and the joint distribution of the charged lepton pseudorapidity and transverse momentum ($\eta$-$p_T$). The distribution of $h_W$/$Y_W$ is measured through a fit to the observed $\eta$-$p_T$ distribution in data with several simulated signal templates, obtained in different bins of $h_W$/$Y_W$, and background templates. In this talk, the measurement of $h_W$/$Y_W$ with the CMS detector is presented, and the prospects in view of the measurement of $m_W$ with CMS data are also discussed.