Higgs boson mass measurement using $H\to ZZ\to 4\mathrm{\ell }$ decays at CMS

A summary of the methods used to make a precision measurement of the Higgs boson mass is presented. The final mass value for the Higgs boson is measured to be $m_{\mathrm{H}}=125.26\pm 0.21\mathrm{G}\mathrm{e}\mathrm{V}$. This analysis considers the $\mathrm{H}\to \mathrm{Z}\mathrm{Z}\to 4\mathrm{\ell }$ channel ($\ell = e, \mu$), using proton-proton collision data collected in 2016 corresponding to an integrated luminosity of $35.9{\mathrm{f}\mathrm{b}}^{-1}$ at $\sqrt{s}=13$ TeV by the CMS experiment at the LHC. A mass constraint is imposed on the invariant mass of the two leptons coming from the mostly on-shell Z boson to refit the lepton momenta and, hence, improve the measurement of the Higgs boson mass, per-event. The mass of the Higgs boson is extracted using a three-dimensional likelihood fit, which uses three observables per-event: (1) the refitted four-lepton invariant mass ($m_{4\mathrm{\ell }}^{\mathrm{\prime }}$), (2) the refitted four-lepton mass uncertainty (${\mathcal{D}}_{\mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s}}^{\mathrm{\prime }}$), and (3) a matrix element-based kinematic discriminant (${\mathcal{D}}_{\mathrm{b}\mathrm{k}\mathrm{g}}^{\mathrm{k}\mathrm{i}\mathrm{n}}$).