Abstract
Evidence is presented for the electroweak (EW) production of two jets (jj) in association with two Z bosons and constraints on anomalous quartic gauge couplings are set. The analysis is based on a data sample of proton-proton collisions at s=13TeV collected with the CMS detector in 2016–2018, and corresponding to an integrated luminosity of 137fb−1. The search is performed in the fully leptonic final state ZZ→ℓℓℓ′ℓ′, where ℓ,ℓ′=e,μ. The EW production of two jets in association with two Z bosons is measured with an observed (expected) significance of 4.0 (3.5) standard deviations. The cross sections for the EW production are measured in three fiducial volumes and the result is σEW(pp→ZZjj→ℓℓℓ′ℓ′jj)=0.33−0.10+0.11(stat)−0.03+0.04(syst)fb in the most inclusive volume, in agreement with the standard model prediction of 0.275±0.021fb. Measurements of total cross sections for jj production in association with two Z bosons are also reported. Limits on anomalous quartic gauge couplings are derived in terms of the effective field theory operators T0, T1, T2, T8, and T9.
Highlights
In the standard model (SM), the electroweak (EW) vector bosons, like the other fundamental particles, acquire their masses through the coupling to the Brout-Englert-Higgs field
The photon remains massless, with only two degrees of polarization, whereas the W and Z bosons acquire an additional degree of freedom, as a consequence of the electroweak symmetry breaking (EWSB) [1,2]
The scattering of massive vector bosons is at the heart of the EWSB mechanism and its study can lead to significant insight into the origin of particle masses
Summary
In the standard model (SM), the electroweak (EW) vector bosons, like the other fundamental particles, acquire their masses through the coupling to the Brout-Englert-Higgs field. The decay of the vector bosons into fermions defines the final signature of the VBS-like event. Kinematic requirements on the dijet system are used to define fiducial regions enriched in VBS-like events and where QCDinduced backgrounds are suppressed. Both the ATLAS and CMS Collaborations have performed searches for the scattering of massive vector bosons, using data from proton-proton (pp) collisions at the center-of-mass energy of 13 TeV. Results were reported on the measurement of the EW diboson production (WW, WZ, ZZ) in association with a highmass dijet system in semileptonic final states [8], with an observed significance of 2.7 standard deviations. The selected jj events are used to constrain anomalous quartic gauge couplings (aQGC) described in the effective field theory approach [17] by the operators T0, T1, and T2, as well as the neutral-current operators T8 and T9 [18]
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