Precision measurement of the W boson mass with the CMS Experiment in pp collisions at √s = 13 TeV

Abstract

The mass of the W boson, mW, is an important fundamental constant of nature, which is also potentially sensitive to a plethora of physics beyond the Standard Model. In this thesis, we discuss the precision measurement of mW with the CMS detector at the LHC in proton-proton collisions at √s = 13 TeV. The phenomenology of W bosons produced in pp collisions, the CMS detector characteristics, and other relevant factors are examined to justify the overall strategy to measure mW from the muon transverse momentum and pseudorapidity spectrum [formula] in the W → µν channel with a part of the 2016 data corresponding to an integrated luminosity of 16.8 fb⁻¹. Dedicated studies aiming to reduce systematic uncertainties related to the muon transverse momentum calibration, the muon reconstruction and background rejection efficiencies, and the modeling of the W boson production and decay kinematics are presented. A profiled maximum-likelihood fit of MC templates to observed data incorporating over 4,000 nuisance parameters is employed to extract the central value and the total uncertainty on m_W. The result of this measurement is m_W = 80, 360.2 ± 2.4 (stat.) ± 9.6 (syst.) MeV,= 80, 360.2 ± 9.9 MeV, which is consistent with the standard model prediction m(SM/W) = 80, 354.5 ± 5.7 MeV.