Evidence for WW production from double-parton interactions in proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports the first evidence for WW production from double-parton scattering in proton-proton collisions at 13 TeV, using CMS data and advanced analysis techniques to identify a rare process.

Contribution

It provides the first experimental evidence for WW production via double-parton scattering at the LHC, with a measured cross section and significance.

Findings

Evidence for WW production from double-parton scattering with 3.9 sigma significance.

Measured inclusive cross section of 1.41 ± 0.28 pb.

Use of multivariate classifiers to distinguish signal from background.

Abstract

A search for WW 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 TeV. The analyzed data set corresponds to an integrated luminosity of 77.4 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 WW production via double-parton scattering, with a significance of 3.9 standard deviations. The measured inclusive cross section is 1.41 $\pm$ 0.28 (stat) $\pm$ 0.28 (syst) pb.