› › Measurement Of The Zz Production Cross Section And Z U2192 L Lu2013l L U2013 Branching Fraction In Pp Collisions At

Measurement of the ZZ Production Cross Section and Z {u2192} L+l{u2013}l'+l'{u2013} Branching Fraction in Pp Collisions at

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Page : 24 pages

File Size : 23,99 MB

Release : 2016

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Here, four-lepton production in proton–proton collisions, pp→(Z/?*)(Z/?*)→l+l–l'+l'–,where l,l'=e or ?, 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, ?(pp → ZZ)=14.6–1.8+1.9(stat)–0.3+0.5(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 60msublsup+/suplsup–/sup/sub,ml'sup+/supl'sup–/sup120 GeV60mlsup+/suplsup–/sup,ml'sup+/supl'sup–/sup120 GeV. The Z boson branching fraction to four leptons is measured to be B(Z→lsup+/suplsup–/supl'sup+/supl'sup–/sup)=4.9sub–0.7/subsup+0.8/sup (stat)sub–0.2/subsup+0.3/sup (syst)–0.1+0.2(theo)±0.1(lumi)×10sup–6/sup for the four-lepton invariant mass in the range 80mlsup+/suplsup–/supl'sup+/supl'sup–/sup100 GeV80mlsup+/suplsup–/supl'sup+/supl'sup–/sup



Measurement of the $ZZ$ Production Cross Section and $Z \to \ell^+ \ell^- \ell^{\prime +} \ell^{\prime -}$ Branching Fraction in $pp$ Collisions at $\sqrt{s}

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File Size : 37,53 MB

Release : 2016

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Four-lepton production in proton-proton collisions, pp to (Z/gamma*)(Z/gamma*) to l+l-l'+l'-, where $l, l' = e or mu, 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 inverse femtobarns. The ZZ production cross section, sigma(pp to 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 m[l+l-], m[l'+l'-]



Measurement of the ZZ Production Cross Section in Pp{u00AF} Collisions at S

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File Size : 20,88 MB

Release : 2011

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The authors present a new measurement of the production cross section ?(pp = ZZ) at a center-of-mass energy √s = 1.96 TeV, obtained from the analysis of the four charged lepton final state l+l-l+̀l-̀(l, l ̀= e or ?). They observe ten candidate events with an expected background of 0.37 ± 0.13 events. The measured cross section ?(pp =ZZ) = 1.26-0.37+0.47 (stat) ± 0.14 (syst) pb is in agreement with NLO QCD predictions. This result is combined with a previous result from the ZZ = l+l- ?? channel resulting in a combined cross section of ?(pp = ZZ) = 1.40-0.37-0.43 (stat) ±0.14 (syst) pb.



Measurement of the Inclusive W and Z Production Cross Sections in Pp Collisions at $ \sqrt {s}

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File Size : 27,48 MB

Release : 2011

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A measurement of inclusive W and Z production cross sections in pp collisions at sqrt(s)=7 TeV is presented. The electron and muon decay channels are analyzed in a data sample collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 inverse picobarns. The measured inclusive cross sections are sigma(pp-> WX) B(W-> l nu) = 10.30 +/- 0.02 (stat.) +/- 0.10 (syst.) +/- 0.10 (th.) +/- 0.41 (lumi.) nb and sigma(pp -> ZX) B(Z-> l+̂l-̂) = 0.974 +/- 0.007 (stat.) +/- 0.007 (syst.) +/- 0.018 (th.) +/- 0.039 (lumi.) nb, limited to the dilepton invariant mass range 60 to 120 GeV. The luminosity-independent cross section ratios are [sigma(pp->WX) B(W-> l nu)]/[sigma(pp-> ZX) B(Z->l+̂l-̂)] = 10.54 +/- 0.07 (stat.) +/- 0.08 (syst.) +/- 0.16 (th.) and [sigma(pp->W+̂X) B(W+̂ -> l+̂nu)] / [sigma(pp->W-̂ X) B(W-̂ -> l-̂ nu)] = 1.421 +/- 0.006 (stat.) +/- 0.014 (syst.) +/- 0.029 (th.). The measured values agree with next-to-next-to-leading order QCD cross section calculations based on recent parton distribution functions.



Measurement of W± and Z-boson Production Cross Sections in Pp Collisions at [mml]

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Page : 21 pages

File Size : 12,15 MB

Release : 2016

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Measurements of the W± → l±[nu] and Z → l+l- production cross sections (where l± = e±, [mu]± ) in proton-proton collisions at √s = 13 TeV are presented using data recorded by the ATLAS experiment at the Large Hadron Collider, corresponding to a total integrated luminosity of 81 pb-1. The total inclusive W±-boson production cross sections times the single-lepton-flavour branching ratios are [sigma]Wtot+ =11.83 ± 0.02 (stat)±0.32 (sys)±0.25 (lumi) nb and [sigma]W-tot=8.79±0.02 (stat)±0.24 (sys)±0.18 (lumi) nb for W+ and W- , respectively.



Measurement of WZ and ZZ Production in Pp Collisions at $\sqrt{s}

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Page : 22 pages

File Size : 25,63 MB

Release : 2014

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Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at $\sqrt{s}$ = 8 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 $W \to e\nu, \mu\nu$ or $Z \to e^+ e^-, \mu^+ \mu^-$, or $\nu\bar{\nu})$. The results are based on data corresponding to an integrated luminosity of 18.9 inverse-femtobarns collected with the CMS detector at the Large Hadron Collider. The measured cross sections, $\sigma(pp \to WZ)$ = 30.7 $\pm$ 9.3 (stat.) $\pm$ 7.1 (syst.) $\pm$ 4.1 (th.) $\pm$ 1.0 (lum.) pb and $\sigma(pp \to ZZ)$ = 6.5 $\pm$ 1.7 (stat.) $\pm$ 1.0 (syst.) $\pm$ 0.9 (th.) $\pm$ 0.2 (lum.) pb, are consistent with next-to-leading order quantum chromodynamics calculations.





Measurement of the $ZZ$ Production Cross Section in $pp$ Collisions at $\sqrt{s}$

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File Size : 11,84 MB

Release : 2016

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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+2.2–2.0(stat)+0.9–0.7(syst)+1.0–0.7(lumi) pb. Lastly, the results agree with standard model predictions.



Measurement of the $ZZ$ Production Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}

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File Size : 37,64 MB

Release : 2011

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The authors present a new measurement of the production cross section [sigma](pp̄ = ZZ) at a center-of-mass energy √s = 1.96 TeV, obtained from the analysis of the four charged lepton final state l+l-l`+l`- (l, l` = e or [mu]). They observe ten candidate events with an expected background of 0.37 ± 0.13 events. The measured cross section [sigma](pp̄ =ZZ) = 1.26-0.37+0.47 (stat) ± 0.14 (syst) pb is in agreement with NLO QCD predictions. This result is combined with a previous result from the ZZ = l+l- [nu][̄nu] channel resulting in a combined cross section of [sigma](pp̄ = ZZ) = 1.40-0.37+0.43 (stat) ±0.14 (syst) pb.



A Measurement of the $WZ$ and $ZZ$ Production Cross Sections Using Leptonic Final States in 8.6 Fb${̂-1}$ of $p\bar{p}$ Collisions

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File Size : 32,45 MB

Release : 2012

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We study the processes p{bar p} → WZ → l?ll− and p{bar p} → ZZ → l+l−?{bar {nu}}, where l = e or?. Using 8.6 fb−1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider, we measure the WZ production cross section to be 4.50{sub -0.66}{sup +0.63} pb which is consistent with, but slightly above a prediction of the standard model. The ZZ cross section is measured to be 1.64 ± 0.46 pb, in agreement with a prediction of the standard model. Combination with an earlier analysis of the ZZ → l+l−l+l− channel yields a ZZ cross section of 1.44{sub -0.34}{sup +0.35} pb.