A measurement of the $W^{+}{W}^{-}$ boson pair production cross section in proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ is presented. The data used in this study are collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of $35.9{\mathrm{fb}}^{-1}$. The $W^{+}{W}^{-}$ candidate events are selected by requiring two oppositely charged leptons (electrons or muons). Two methods for reducing background contributions are employed. In the first one, a sequence of requirements on kinematic quantities is applied allowing a measurement of the total production cross section, $117.6\pm 6.8\mathrm{pb}$, which agrees well with the theoretical prediction. Fiducial cross sections are also reported for events with zero or one jet, and the change in the zero-jet fiducial cross section with the jet transverse momentum threshold is measured. Normalized differential cross sections are reported within the fiducial region. A second method for suppressing background contributions employs two random forest classifiers. The analysis based on this method includes a measurement of the total production cross section and also a measurement of the normalized jet multiplicity distribution in $W^{+}{W}^{-}$ events. Finally, a dilepton invariant mass distribution is used to probe for physics beyond the standard model in the context of an effective field theory, and constraints on the presence of dimension-6 operators are derived.

• Received 31 August 2020
• Accepted 28 September 2020

DOI:https://doi.org/10.1103/PhysRevD.102.092001

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© 2020 CERN, for the CMS Collaboration