Studies of the energy dependence of diboson polarization fractions and the Radiation Amplitude Zero effect in WZ production with the ATLAS detector

Abstract

This Letter presents the first study of the energy-dependence of diboson polarization fractions in $WZ\to \ell \nu {\ell }^{\prime }{\ell }^{\prime }(\ell ,{\ell }^{\prime }=e,\mu )$ production. The data set used corresponds to an integrated luminosity of 140 fb${}^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector. Two fiducial regions with an enhanced presence of events featuring two longitudinally-polarized bosons are defined. A non-zero fraction of events with two longitudinally-polarized bosons is measured with an observed significance of 5.2 standard deviations in the region with $100<p_T^Z\le 200$ GeV and 1.6 standard deviations in the region with $p_T^Z>200$ GeV, where $p_T^Z$ is the transverse momentum of the $Z$ boson. This Letter also reports the first study of the Radiation Amplitude Zero effect. Events with two transversely-polarized bosons are analyzed for the $\Delta Y({\ell }_{W}Z)$ and $\Delta Y(WZ)$ distributions defined respectively as the rapidity difference between the lepton from the $W$ boson decay and the $Z$ boson and the rapidity difference between the $W$ boson and the $Z$ boson. Significant suppression of events near zero is observed in both distributions. Unfolded $\Delta Y({\ell }_{W}Z)$ and $\Delta Y(WZ)$ distributions are also measured and compared to theoretical predictions.

arXiv commentComment: 34 pages in total, author list starting page 17, 4 figures, 2 tables, published in Phys. Rev. Lett. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2020-01/. Version three fixes one typo in the abstract

References in corpus (51)

• A Brief Introduction to PYTHIA 8.1
• Parton distributions with LHC data
• The ATLAS Simulation Infrastructure
• PDF4LHC recommendations for LHC Run II
• An update on vector boson pair production at hadron colliders
• Event Generation with Sherpa 2.2
• Performance of the ATLAS Trigger System in 2015
• Vector boson pair production at the LHC
• Performance of pile-up mitigation techniques for jets in $pp$ collisions at $\sqrt{s}=8$ TeV using the ATLAS detector
• Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data
• ATLAS $b$-jet identification performance and efficiency measurement with $t\bar{t}$ events in $pp$ collisions at $\sqrt{s}=13$ TeV
• Jet reconstruction and performance using particle flow with the ATLAS Detector
• Performance of electron and photon triggers in ATLAS during LHC Run 2
• Muon reconstruction and identification efficiency in ATLAS using the full Run 2 $pp$ collision data set at $\sqrt{s}=13$ TeV
• Correcting the Colour-Dipole Cascade Model with Fixed Order Matrix Elements
• Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Jet energy scale and resolution measured in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Electron reconstruction and identification in the ATLAS experiment using the 2015 and 2016 LHC proton-proton collision data at $\sqrt{s}$ = 13 TeV
• $W^{\pm }Z$ production at the LHC: fiducial cross sections and distributions in NNLO QCD
• Vector Boson Pair Production in Hadronic Collisions at Order ${\alpha }_s$: Lepton Correlations and Anomalous Couplings
• ZZ production at the LHC: fiducial cross sections and distributions in NNLO QCD
• $W^{\pm }Z$ production at hadron colliders in NNLO QCD
• Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector
• Vector-boson pair production at the LHC to $\mathcal{O}({\alpha }^3)$ accuracy
• NLO QCD corrections to tri-boson production
• Electron and photon energy calibration with the ATLAS detector using 2015-2016 LHC proton-proton collision data
• Measurement of $W^{\pm }Z$ production cross sections and gauge boson polarisation in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Electroweak Precision Tests in High-Energy Diboson Processes
• Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for supersymmetry at sqrt(s)=8 TeV in final states with jets and two same-sign leptons or three leptons with the ATLAS detector
• Observation of electroweak production of a same-sign $W$ boson pair in association with two jets in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• NNLO QCD+NLO EW with MATRIX+OpenLoops: precise predictions for vector-boson pair production
• Measurement of the W gamma and Z gamma inclusive cross sections in pp collisions at sqrt(s) = 7 TeV and limits on anomalous triple gauge boson couplings
• Identification and rejection of pile-up jets at high pseudorapidity with the ATLAS detector
• Automated Predictions from Polarized Matrix Elements
• On improving NLO merging for $t\bar{t}W$ production
• First study of the radiation-amplitude zero in Wgamma production and limits on anomalous WWgamma couplings at sqrt(s)=1.96 TeV
• $WZ$ Production at Hadron Colliders: Effects of Non-Standard $WWZ$ Couplings and QCD Corrections
• NLO QCD predictions for doubly-polarized WZ production at the LHC
• Amplitude Zeros in $W^{\pm }Z$ Production
• Observation of the associated production of a top quark and a $Z$ boson in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Precision Measurement with Diboson at the LHC
• Fiducial polarization observables in hadronic WZ production: A next-to-leading order QCD+EW study
• Evidence for the production of three massive vector bosons with the ATLAS detector
• Next-to-leading-order electroweak corrections to the production of three charged leptons plus missing energy at the LHC
• Precision Diboson Observables for the LHC
• Observation of gauge boson joint-polarisation states in $W^{\pm }Z$ production from $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Measurement of W${}^{\pm }\gamma$ differential cross sections in proton-proton collisions at $\sqrt{s}$ = 13 TeV and effective field theory constraints
• The Radiation Valley and Exotic Resonances in $W\gamma$ Production at the LHC
• Evidence of pair production of longitudinally polarised vector bosons and study of CP properties in $ZZ\to 4\ell$ events with the ATLAS detector at $\sqrt{s}=13$ TeV
• Electroweak Restoration at the LHC and Beyond: The $Vh$ Channel