ZZ Production Cross Section Research Articles

Measurements of the mathrm {p}mathrm {p}rightarrow mathrm{Z}mathrm{Z} production cross section and the mathrm{Z}rightarrow 4ell branching fraction, and constraints on anomalous triple gauge couplings at sqrt{s} = 13,text {TeV}

Four-lepton production in proton-proton collisions, mathrm {p}mathrm {p}rightarrow (mathrm{Z}/ gamma ^*)(mathrm{Z}/gamma ^*) rightarrow 4ell , where ell = mathrm {e} or mu , is studied at a center-of-mass energy of 13,text {TeV} with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9,text {fb}^{-1}. The ZZ production cross section, sigma (mathrm {p}mathrm {p}rightarrow mathrm{Z}mathrm{Z}) = 17.2 pm 0.5,text {(stat)} pm 0.7,text {(syst)} pm 0.4,text {(theo)} pm 0.4,text {(lumi)} text { pb} , measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60< m_{ell ^+ell ^-} < 120,text {GeV} , is consistent with standard model predictions. Differential cross sections are measured and are well described by the theoretical predictions. The Z boson branching fraction to four leptons is measured to be mathcal {B}(mathrm{Z}rightarrow 4ell ) = 4.83 _{-0.22}^{+0.23} (stat)_{-0.29}^{+0.32} (syst) pm 0.08 (theo) pm 0.12 (lumi) times 10^{-6} for events with a four-lepton invariant mass in the range 80< m_{4ell } < 100,text {GeV} and a dilepton mass m_{ell ell } > 4,text {GeV} for all opposite-sign, same-flavor lepton pairs. The results agree with standard model predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZgamma couplings at 95% confidence level: -0.0012<f_4^mathrm{Z}<0.0010, -0.0010<f_5^mathrm{Z}<0.0013, -0.0012<f_4^{gamma }<0.0013, -0.0012<f_5^{gamma }< 0.0013.

Measurement of the ZZ production cross section in proton-proton collisions at sqrt{s}=8 TeV using the ZZ \u2192 \u2113\u2212\u2113+\u2113\u2032\u2212\u2113\u2032+ and ZZto {ell}^{-}{ell}^{+}nu overline{nu} decay channels with the ATLAS detector

A measurement of the ZZ production cross section in the ℓ−ℓ+ℓ′ −ℓ′ + and {ell}^{-}{ell}^{+}nu overline{nu} channels (ℓ = e, μ) in proton-proton collisions at sqrt{s}=8 TeV at the Large Hadron Collider at CERN, using data corresponding to an integrated luminosity of 20.3 fb−1 collected by the ATLAS experiment in 2012 is presented. The fiducial cross sections for ZZ → ℓ−ℓ+ℓ′ −ℓ′ + and ZZto {ell}^{-}{ell}^{+}nu overline{nu} are measured in selected phase-space regions. The total cross section for ZZ events produced with both Z bosons in the mass range 66 to 116 GeV is measured from the combination of the two channels to be 7.3 ± 0.4(stat) ± 0.3(syst)− 0.1− 0.2(lumi) pb, which is consistent with the Standard Model prediction of 6. 6− 0.6+ 0.7 pb. The differential cross sections in bins of various kinematic variables are presented. The differential event yield as a function of the transverse momentum of the leading Z boson is used to set limits on anomalous neutral triple gauge boson couplings in ZZ production.

Measurement of the ZZ production cross section and Z →ℓ+ℓ−ℓ′+ℓ′− branching fraction in pp collisions at s=13 TeV

Four-lepton production in proton–proton collisions, pp→(Z/γ^*)(Z/γ^*)→l^+l^−l^(′+)l^(′−), where l,l′=e or μ, is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.6 fb^(−1). The ZZ production cross section, σ(pp → ZZ = 14.6^(+1.9)_(-1.8) (stat)^(+0.5)_(-0.3) (syst) ± 0.2(theo)± 0.4(lumi)pb, is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60 4 GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.

Corrigendum to “Measurement of the pp → ZZ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at s=8TeV” [Phys. Lett. B 740 (2015) 250

Corrigendum to “Measurement of the pp → ZZ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>8</mml:mn><mml:mspace width="0.25em"/><mml:mtext>TeV</mml:mtext></mml:math>” [Phys. Lett. B 740 (2015) 250

Production of vector bosons and jets at CMS

The production cross section of highly boosted vector bosons (V = W, Z) recoiling against jets is studied, with CMS data, differentially as function of the transverse momentum and angular correlations of the final state particles. The mechanism of production of heavy-flavoured mesons, containing b or c quarks, in association with vector bosons, W or Z, in the Standard Model is only partially understood. The study of events with one or two well-identified and isolated leptons accompanied by b-jets or b-mesons is therefore crucial to refine the theoretical calculations in perturbative QCD, as well as validate associated Monte Carlo techniques. A measurement of the WZ and ZZ production cross sections in proton-proton collisions at 8 TeV in final states where one Z boson decays to b-tagged jets, while the other gauge boson, either W or Z, is detected through its leptonic decay is also presented.

Measurement of theZZProduction Cross Section inppCollisions ats=13 TeVwith the ATLAS Detector

The ZZ production cross section in proton-proton collisions at 13 TeV center-of-mass energy is measured using 3.2 fb−1 of data recorded with the ATLAS detector at the Large Hadron Collider. The considered Z boson candidates decay to an electron or muon pair of mass 66–116 GeV. The cross section is measured in a fiducial phase space reflecting the detector acceptance. It is also extrapolated to a total phase space for Z bosons in the same mass range and of all decay modes, giving 16.7−2.0+2.2(stat)+0.9−0.7(syst)+1.0−0.7(lumi) pb. The results agree with standard model predictions.Received 17 December 2015DOI:https://doi.org/10.1103/PhysRevLett.116.101801This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.© 2016 CERN, for the ATLASPhysics Subject Headings (PhySH)Research AreasElectroweak interactionParticle productionW & Z bosonsTechniquesHadron collidersMulti-purpose particle detectorsParticles & Fields

Measurements of the [Formula: see text][Formula: see text] production cross sections in the [Formula: see text] channel in proton-proton collisions at [Formula: see text] and [Formula: see text] and combined constraints on triple gauge couplings.

Measurements of the mathrm{Z}mathrm{Z} production cross sections in proton–proton collisions at center-of-mass energies of 7 and 8~mathrm{TeV} are presented. Candidate events for the leptonic decay mode mathrm{Z}mathrm{Z}rightarrow 2mathrm{l} 2nu , where mathrm{l} denotes an electron or a muon, are reconstructed and selected from data corresponding to an integrated luminosity of 5.1 (19.6),text {fb}^text {-1} at 7 (8)~mathrm{TeV} collected with the CMS experiment. The measured cross sections, sigma (mathrm {p}mathrm {p}rightarrow mathrm{Z}mathrm{Z}) = 5.1_{-1.4}^{+1.5},text {(stat)} ,_{-1.1}^{+1.4},text {(syst)} pm 0.1,text {(lumi)} text {~pb} at 7~mathrm{TeV}, and 7.2_{-0.8}^{+0.8},text {(stat)} ,_{-1.5}^{+1.9},text {(syst)} ,pm , 0.2,text {(lumi)} text {~pb} at 8~mathrm{TeV}, are in good agreement with the standard model predictions with next-to-leading-order accuracy. The selected data are analyzed to search for anomalous triple gauge couplings involving the mathrm{Z}mathrm{Z} final state. In the absence of any deviation from the standard model predictions, limits are set on the relevant parameters. These limits are then combined with the previously published CMS results for mathrm{Z}mathrm{Z} in 4mathrm{l} final states, yielding the most stringent constraints on the anomalous couplings.

Measurement of the [formula omitted] production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at [formula omitted

A measurement of the inclusive ZZ production cross section and constraints on anomalous triple gauge couplings in proton–proton collisions at s=8 TeV are presented. The analysis is based on a data sample, corresponding to an integrated luminosity of 19.6 fb−1, collected with the CMS experiment at the LHC. The measurements are performed in the leptonic decay modes ZZ→ℓℓℓ′ℓ′, where ℓ=e,μ and ℓ′=e,μ,τ. The measured total cross section σ(pp→ZZ)=7.7±0.5 (stat)−0.4+0.5 (syst)±0.4(theo)±0.2 (lumi) pb, for both Z bosons produced in the mass range 60<mZ<120 GeV, is consistent with standard model predictions. Differential cross sections are measured and well described by the theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZγ couplings at the 95% confidence level: −0.004<f4Z<0.004, −0.004<f5Z<0.004, −0.005<f4γ<0.005, and −0.005<f5γ<0.005.

Measurement of WZ and ZZ production in pp collisions at [Formula: see text] in final states with b-tagged jets.

Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at sqrt{s} = 8 ,text {TeV} in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either mathrm {W}rightarrow mathrm {e}nu , mathrm {mu }nu or mathrm {Z}rightarrow mathrm {e}^+mathrm {e}^-, mathrm {mu ^+}mathrm {mu ^-}, or {nu }overline{nu }). The results are based on data corresponding to an integrated luminosity of 18.9 fb^{-1} collected with the CMS detector at the Large Hadron Collider. The measured cross sections, sigma (mathrm {p}mathrm {p}rightarrow mathrm {W}mathrm {Z}) = 30.7 pm 9.3,text {(stat.)} pm 7.1,text {(syst.)} pm 4.1,text {(th.)} pm 1.0,text {(lum.)} ,text {pb} and sigma (mathrm {p}mathrm {p}rightarrow mathrm {Z}mathrm {Z}) = 6.5 pm 1.7,text {(stat.)} pm 1.0,text {(syst.)} pm 0.9,text {(th.)} pm 0.2,text {(lum.)} ,text {pb} , are consistent with next-to-leading order quantum chromodynamics calculations.

Search for a dijet resonance in events with jets and missing transverse energy inpp¯collisions ats=1.96 TeV

We report on a search for a dijet resonance in events with only two or three jets and large imbalance in the total event transverse momentum. This search is sensitive to the possible production of a new particle in association with a $W$ or $Z$ boson, where the boson decays leptonically with one or more neutrinos in the final state. We use the full data set collected by the CDF II detector at the Tevatron collider at a proton-antiproton center-of-mass energy of 1.96 TeV. These data correspond to an integrated luminosity of 9.1 fb$^{-1}$. We study the invariant mass distribution of the two jets with highest transverse energy. We find good agreement between data and standard model background expectations and measure the combined cross section for WW, WZ, and ZZ production to be $13.8^{+3.0}_{-2.7}$ pb. No significant anomalies are observed in the mass spectrum and 95% credibility level upper limits are set on the production rates of a potential new particle in association with a $W$ or $Z$ boson.

Search forZH→ℓ+ℓ−bb¯production in9.7 fb−1ofpp¯collisions with the D0 detector

We present a search for the standard model (SM) Higgs boson produced in association with a Z boson in 9.7 fb-1 of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt{s} = 1.96 TeV. Selected events contain one reconstructed Z -> e+e- or Z -> mu+mu- candidate and at least two jets, including at least one jet likely to contain a b quark. To validate the search procedure, we also measure the cross section for ZZ production, and find that it is consistent with the SM expectation. We set upper limits at the 95% C.L. on the product of the ZH production cross section and branching ratio B(H -> bbbar) for Higgs boson masses 90

Measurement of the [formula omitted] and ZZ production cross sections in pp collisions at [formula omitted

The W+W− and ZZ production cross sections are measured in proton–proton collisions at s=8 TeV with the CMS experiment at the LHC in data samples corresponding to an integrated luminosity of up to 5.3 fb−1. The measurements are performed in the leptonic decay modes W+W−→ℓ′νℓ″ν and ZZ→2ℓ2ℓ′, where ℓ=e,μ and ℓ′(ℓ″)=e,μ,τ. The measured cross sections σ(pp→W+W−)=69.9±2.8(stat.)±5.6(syst.)±3.1(lum.) pb and σ(pp→ZZ)=8.4±1.0(stat.)±0.7(syst.)±0.4(lum.) pb, for both Z bosons produced in the mass region 60<mZ<120 GeV, are consistent with standard model predictions. These are the first measurements of the diboson production cross sections at s=8 TeV.

Measurement of ZZ production in pp collisions at $ \sqrt{s}=7 $ TeV and limits on anomalous ZZZ and ZZγ couplings with the ATLAS detector

AbstractA measurement of theZZproduction cross section in proton-proton collisions at$ \sqrt{s}=7 $TeV using data recorded by the ATLAS experiment at the Large Hadron Collider is presented. In a data sample corresponding to an integrated luminosity of 4.6 fb−1collected in 2011, events are selected that are consistent either with twoZbosons decaying to electrons or muons or with oneZboson decaying to electrons or muons and a secondZboson decaying to neutrinos. TheZZ(*)→ℓ+ℓ−ℓ′+ℓ′−and$ ZZ\to {\ell^{+}}{\ell^{-}}\nu \overline{\nu} $cross sections are measured in restricted phase-space regions. These results are then used to derive the total cross section forZZevents produced with bothZbosons in the mass range 66 to 116 GeV,$ \sigma_{ZZ}^{\mathrm{tot}} = 6.7 \pm 0.7\;\,\left( {\mathrm{stat}.} \right)\;\;_{-0.3}^{+0.4}\;\,\left( {\mathrm{syst}.} \right) \pm 0.3\;\,\left( {\mathrm{lumi}.} \right) $pb, which is consistent with the Standard Model prediction of$ 5.89_{-0.18}^{+0.22 } $pb calculated at next-to-leading order in QCD. The normalized differential cross sections in bins of various kinematic variables are presented. Finally, the differential event yield as a function of the transverse momentum of the leadingZboson is used to set limits on anomalous neutral triple gauge boson couplings inZZproduction.

Measurement of the ZZ production cross section and search for anomalous couplings in 2ℓ2ℓ′ final states in pp collisions at $ \sqrt{s}=7 $ TeV

Abstract A measurement is presented of the ZZ production cross section in the ZZ → 2ℓ2ℓ′ decay mode with ℓ = e, μ and ℓ′ = e, μ, τ in proton-proton collisions at $ \sqrt{s}=7 $ TeV with the CMS experiment at the LHC. Results are based on data corresponding to an integrated luminosity of 5.0 fb−1. The measured cross section $ \sigma \left( {\mathrm{pp}\to \mathrm{ZZ}} \right)=6.24_{-0.80}^{+0.86}\left( {\mathrm{stat}.} \right)_{-0.32}^{+0.41}\left( {\mathrm{syst}.} \right)\pm 0.14\left( {\mathrm{lumi}.} \right)\mathrm{pb} $ is consistent with the standard model predictions. The following limits on ZZZ and ZZγ anomalous trilinear gauge couplings are set at 95% confidence level: $ -0.011&lt;f_4^{\mathrm{Z}}&lt;0.012,-0.012&lt;f_5^{\mathrm{Z}}&lt;0.012,-0.013&lt;f_4^{\upgamma}&lt;0.015 $ , and $ -0.014&lt;f_5^{\upgamma}&lt;0.014 $ .

Search for the Standard Model Higgs Boson inZH→ℓ+ℓ−bb¯Production with the D0 Detector in9.7 fb−1ofpp¯Collisions ats=1.96 TeV

We present a search for the standard model (SM) Higgs boson produced in association with a Z boson in 9.7 fb-1 of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt(s) = 1.96 TeV. Selected events contain one reconstructed Z-> e+e- or Z-> mu+mu- candidate and at least two jets, including at least one jet identified as likely to contain a b quark. To validate the search procedure, we also measure the cross section for ZZ production in the same final state. It is found to be consistent with its SM prediction. We set upper limits on the ZH production cross section times branching ratio for H->bbbar at the 95% C.L. for Higgs boson masses 90 < M_H < 150 GeV. The observed (expected) limit for M_H = 125 GeV is 7.1 (5.1) times the SM cross section.

Search for the standard model Higgs boson in the [formula omitted] channel in 9.5 fb−1 of [formula omitted] collisions at [formula omitted

We present a search for the standard model Higgs boson in 9.5 fb−1 of pp¯ collisions at s=1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered contains a pair of b jets and is characterized by an imbalance in transverse energy, as expected from pp¯→ZH→νν¯bb¯ production. The search is also sensitive to the WH→ℓνbb¯ channel when the charged lepton is not identified. The data are found to be in good agreement with the expected background. For a Higgs boson mass of 125 GeV, we set a limit at the 95% C.L. on the cross section σ(pp¯→[Z/W]H), assuming standard model branching fractions, that is a factor of 4.3 times larger than the theoretical standard model value, while the expected factor is 3.9. The search is also used to measure a combined WZ and ZZ production cross section that is a factor of 0.94±0.31(stat)±0.34(syst) times the standard model prediction of 4.4 pb, with an observed significance of 2.0 standard deviations.

Measurement ofZZProduction in Leptonic Final States atsof 1.96 TeV at CDF

In this Letter, we present a precise measurement of the total ZZ production cross section in pp collisions at sqrt[s]=1.96 TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of approximately 6 fb(-1). The result is obtained by combining separate measurements in the four-charged (ℓℓℓ' ℓ') and two-charged-lepton and two-neutral-lepton (ℓℓνν) decay modes of the Z boson pair. The combined measured cross section for pp → ZZ is 1.64(-0.38)(+0.44) pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.

Measurement of theZZProduction Cross Section and Limits on Anomalous Neutral Triple Gauge Couplings in Proton-Proton Collisions ats=7 TeVwith the ATLAS Detector

A measurement of the ZZ production cross section in proton-proton collisions at sqrt(s) = 7 TeV using data recorded by the ATLAS experiment at the LHC is presented. In a data sample corresponding to an integrated luminosity of 1.02 fb^-1 collected in 2011, 12 events containing two Z boson candidates decaying to electrons and/or muons are observed. The expected background contribution is 0.3 +/- 0.3 (stat) ^{+0.4}_{-0.3} (syst.) events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 GeV to 116 GeV is sigma_{ZZ to ll ll}^{fid} = 19^{+6}_{-5} (stat.) +/- 1 (syst.) +/- 1 (lumi.) fb. This result is then used to derive the total cross section for on-shell ZZ production, sigma_{ZZ}^{tot}= 8.5^{+2.7}_{-2.3} (stat.)^{+0.4}_{-0.3} (syst.) +/- 0.3 (lumi.) pb, which is consistent with the Standard Model expectation of 6.5^{+0.3}_{-0.2} pb calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived.

Measurement of Z-pair production in e+e−collisions and constraints on anomalous neutral gauge couplings

The ZZ production cross section is measured from a data sample corresponding to a total integrated luminosity of 452 pb−1, collected by the ALEPH experiment at LEP at centre-of-mass energies from 192 to 209 GeV. Individual cross sections, extracted at six centre-of-mass energies, are found to be in agreement with Standard Model calculations. The results are used to set limits on anomalous neutral gauge couplings.

Diboson physics at CDF

This article presents the most recent results of the diboson production properties, using up to ∫ Ldt = 1.9 fb-1 of data taken with the CDF Run II detector, at Tevatron. We summarize measurements of the Wγ, Zγ, WW, WZ and ZZ production cross sections in leptonic channels. A search for the combined WW and WZ production in lepton-neutrino plus dijet final states is also presented.