Publication: Evidence for $\text {W}\text {W}$ production from double-parton interactions in proton–proton collisions at $\sqrt{s} = 13 \,\text {TeV} $

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A search for $\text {W}\text {W}$ production from double-parton scattering processes using same-charge electron-muon and dimuon events is reported, based on proton-proton collision data collected at a center-of-mass energy of $13\,\text {TeV} $. The analyzed data set corresponds to an integrated luminosity of $77.4{\,\text {fb}^{-1}} $, collected using the CMS detector at the LHC in 2016 and 2017. Multivariate classifiers are used to discriminate between the signal and the dominant background processes. A maximum likelihood fit is performed to extract the signal cross section. This leads to the first evidence for $\text {W}\text {W}$ production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is $1.41\pm 0.28\,\text {(stat)} \pm 0.28\,\text {(syst)} \,\text {pb} $.