Observation of the production of three massive gauge bosons at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports the first observation of the combined production of three massive gauge bosons (VVV) in proton-proton collisions at 13 TeV, confirming the Standard Model predictions with high significance.

Contribution

It provides the first observation of the combined VVV production at the LHC, measuring cross sections and significances for individual and combined triboson processes.

Findings

Combined VVV production observed with 5.7 sigma significance.

Measured cross section is consistent with the Standard Model.

Significances for WWW and WWZ are 3.3 and 3.4 sigma, respectively.

Abstract

The first observation is reported of the combined production of three massive gauge bosons (VVV with V = W,Z) in proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is based on a data sample recorded by the CMS experiment at the CERN LHC corresponding to an integrated luminosity of 137 fb$^{-1}$. The searches for individual WWW, WWZ, WZZ, and ZZZ production are performed in final states with three, four, five, and six leptons (electrons or muons), or with two same-sign leptons plus one or two jets. The observed (expected) significance of the combined VVV production signal is 5.7 (5.9) standard deviations and the corresponding measured cross section relative to the standard model prediction is 1.02 $^{+0.26}_{-0.23}$. The significances of the individual WWW and WWZ production are 3.3 and 3.4 standard deviations, respectively. Measured production cross sections for the individual triboson processes are also reported.