Polarization Asymmetries in Gamma E Collisions and Triple Gauge Boson Couplings Revisited

Polarization Asymmetries in Gamma E Collisions and Triple Gauge Boson Couplings Revisited

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Published: 2004

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The capability of the NLC run in the[gamma]e collision mode to probe the CP-conserving[gamma]WW and[gamma]ZZ anomalous couplings through the use of the polarization asymmetry is reviewed. When combined with other measurements, very strong constraints on both varieties of anomalous couplings can be obtained. We show that these bounds are complementary to those that can be extracted from data taken at the LHC.


Measurement of the Z[gamma] Production Cross Section in Pp Collisions at 8 TeV and Search for Anomalous Triple Gauge Boson Couplings

Measurement of the Z[gamma] Production Cross Section in Pp Collisions at 8 TeV and Search for Anomalous Triple Gauge Boson Couplings

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Published: 2015

Total Pages: 39

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The cross section for the production of Z[gamma] in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb-1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. Furthermore, the differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. These observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. As a result, limits on anomalous triple gauge couplings of ZZ[gamma] and Z[gamma][gamma] are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.


A Search for WW$\gamma$ and WZ$\gamma$ Triboson Production and Anomalous Quartic Gauge Couplings at $\sqrt{s}$

A Search for WW$\gamma$ and WZ$\gamma$ Triboson Production and Anomalous Quartic Gauge Couplings at $\sqrt{s}$

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Published: 2016

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An analysis probing for the standard model production of three electroweak vector bosons, WV$\gamma$ with V = W or Z gauge boson, is presented. The W boson decays leptonically to an electron or muon, or their respective antiparticle, paired with the appropriate neutrino. The second boson V decays hadronically into two jets, and additionally a photon is required in the event. The data analyzed correspond to an integrated luminosity of 19.6~fb$^{-1}$ and 2.3~fb$^{-1}$ from proton-proton collisions at $\sqrt{s}$ = 8~TeV and 13~TeV, respectively, collected in 2012 and 2015 by the CMS detector at the Large Hadron Collider. The event selection criteria used in these analyses yields 322 and 46 observed events in data in 2012 and 2015, respectively, while the estimated background yield from theoretical predictions is 342.1~$\pm$~22.2 and 54.3~$\pm$~17.7. These observations are consistent with the standard model next-to-leading order QCD predictions. Given the limitation in statistics to measure the cross section for this production process, an upper limit of 3.4 times the standard model predictions is made at a 95\% confidence level for WV$\gamma$ with photon $p_{T}$ greater than 30~GeV and absolute pseudorapidity less than 1.44. Physics beyond the standard model, such as anomalous couplings between the gauge bosons at the quartic vertex, may lead to enhancement in the number of WV$\gamma$ events produced within high energy collisions. Such enhancements can be observed in kinematic distributions, particularly in the higher energy regions. No evidence of anomalous WW$\gamma\gamma$ and WWZ$\gamma$ quartic gauge boson couplings is found, while 95\% confidence level upper limits are obtained for various couplings.