Measurements of the Higgs boson mass and width at CMS

The Higgs boson mass ($m_H$) and its total decay width ($\Gamma_H$) are key parameters that define the properties of the scalar sector of the Standard Model (SM). Their precise determination, in the diphoton ($H\to\gamma\gamma$) and the four-lepton ($H\to ZZ^*\to4\ell$) channels, is essential both to test the self-consistency of the SM and to constrain possible contributions from physics beyond the SM. The most recent combination of these channels yields a mass of $m_H=125.38\pm0.14~\mathrm{GeV}$. The Higgs boson width is measured combining on-shell and off-shell $ZZ$ production, obtaining a value of $\Gamma_H = 3.0^{+2.0}_{-1.5}~\mathrm{MeV}$, consistent with the SM expectation of $4.1~\mathrm{MeV}$. The scenario of no off-shell Higgs boson production is excluded at a confidence level corresponding to 3.8 standard deviations.