Speaker
Description
We present a search for the electroweak production of two Z bosons in association with two jets at a center-of-mass energy of 13 TeV. The analysis focuses on the decay channel with two charged leptons (electrons or muons) and two neutrinos, which features a relatively large branching fraction but also suffers from sizable backgrounds and incomplete event reconstruction due to the presence of neutrinos.To enhance the separation between the electroweak signal and the dominant backgrounds, a machine-learning based graph neural network discriminator is employed, together with multiple dedicated control regions to constrain background contributions. In particular, a fully data-driven estimation of the Drell–Yan background plays a crucial role in the analysis. The expected (observed) significance in the 2ℓ2ν channel is 2.8 (3.1) standard deviations. When combined with the VBS ZZ 4ℓ channel, the expected (observed) significance becomes 4.5 (5.0) standard deviations, thereby we claim observation of the last electroweak production of vector diboson processes in CMS experiment. In addition, we measure the fiducial cross section and set limits on dimension-8 EFT operators.
