L Sartori

Publications (545)1083 Total impact

• Article: Measurement of the Mass Difference Between Top and Anti-top Quarks at CDF

  T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We present a measurement of the mass difference between top ($t$) and anti-top ($\bar{t}$) quarks using $t\bar{t}$ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb$^{-1}$. We estimate event-by-event the mass difference to construct templates for top-quark signal events and background events. The resulting mass difference distribution of data compared to signal and background templates using a likelihood fit yields $\Delta M_{top} = {M}_{t} - {M}_{\bar{t}} = -1.95 $pm$ 1.11 (stat) $pm$ 0.59 (syst)$ and is in agreement with the standard model prediction of no mass difference.
  10/2012;
• Article: Search for the Higgs boson in the all-hadronic final state using the full CDF data set

  CDF Collaboration, T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: This paper reports the result of a search for the standard model Higgs boson in events containing four reconstructed jets associated with quarks. For masses below 135GeV/c2, Higgs boson decays to bottom-antibottom quark pairs are dominant and result primarily in two hadronic jets. An additional two jets can be produced in the hadronic decay of a W or Z boson produced in association with the Higgs boson, or from the incoming quarks that produced the Higgs boson through the vector-boson fusion process. The search is performed using a sample of \sqrt{s} = 1.96 TeV proton-antiproton collisions corresponding to an integrated luminosity of 9.45 fb-1 recorded by the CDF II detector. The data are in agreement with the background model and 95% credibility level upper limits on Higgs boson production are set as a function of the Higgs boson mass. The median expected (observed) limit for a 125GeV/c2 Higgs boson is 11.0 (9.0) times the predicted standard model rate.
  08/2012;
• Article: Precision Top-Quark Mass Measurements at CDF

  T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We present a precision measurement of the top-quark mass using the full sample of Tevatron $\sqrt{s}=1.96$ TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 $fb^{-1}$. Using a sample of $t\bar{t}$ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the $W$ boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, $\mtop = 172.85 $\pm$ 0.71 (stat) $\pm$ 0.85 (syst) GeV/c^{2}.$
  07/2012;
• Article: An inclusive search for the Higgs boson in the four-lepton final state at CDF

  T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: An inclusive search for the standard model Higgs boson using the four-lepton final state in proton-antiproton collisions produced by the Tevatron at sqrt(s) = 1.96 TeV is conducted. The data are recorded by the CDF II detector and correspond to an integrated luminosity of 9.7 /fb. Three distinct Higgs decay modes, namely ZZ, WW, and tau-tau, are simultaneously probed. Nine potential signal events are selected and found to be consistent with the background expectation. We set a 95% credibility limit on the production cross section times the branching ratio and subsequent decay to the four lepton final state for hypothetical Higgs boson masses between 120 GeV/c^2 and 300 GeV/c^2.
  07/2012;
• Article: Production of Λ0, Λ̅ 0, Ξ±, and Ω± hyperons in pp̅ collisions at √s=1.96 TeV

  T. Aaltonen, B. Álvarez González, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We report a set of measurements of inclusive invariant pT differential cross sections of Λ0, Λ̅ 0, Ξ±, and Ω± hyperons reconstructed in the central region with pseudorapidity |η|<1 and pT up to 10 GeV/c. Events are collected with a minimum-bias trigger in pp̅ collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As pT increases, the slopes of the differential cross sections of the three particles are similar, which could indicate a universality of the particle production in pT. The invariant differential cross sections are also presented for different charged-particle multiplicity intervals.
  Phys. Rev. D. 07/2012; 86(1).
• Article: Production of Λ0, Λ̅0, Ξ±, and Ω± hyperons in pp̅ collisions at √s=1.96 TeV

  T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
  Phys. Rev. D. 07/2012; 86(1):012002.
• Article: Search for a low-mass standard model Higgs boson in the ττ decay channel in pp collisions at sqrt[s]=1.96  TeV.

  T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: We report on a search for the standard model Higgs boson decaying into pairs of τ leptons in pp collisions produced by the Tevatron at sqrt[s]=1.96  TeV. The analyzed data sample was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0  fb(-1). The search is performed in the final state with one τ decaying leptonically and the second one identified through its semihadronic decay. Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the ττ final state is set for hypothetical Higgs boson masses between 100 and 150  GeV/c2. For a Higgs boson of 120  GeV/c2 the observed (expected) limit is 14.6 (15.3) the predicted value.
  Physical Review Letters 05/2012; 108(18):181804. · 7.37 Impact Factor
• Article: Improved determination of the sample composition of dimuon events produced in collisions at TeV

  The CDF Collaboration, T. Aaltonen, B. ÁlvarezGonzález, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We use a new method to estimate with 5% accuracy the contribution of pion and kaon in-flight-decays to the dimuon data set acquired with the CDF detector. Based on this improved estimate, we show that the total number and the properties of the collected dimuon events are not yet accounted for by ordinary sources of dimuons which also include the contributions, as measured in the data, of heavy flavor, ϒ, and Drell–Yan production in addition to muons mimicked by hadronic punchthrough. The number of unaccounted events corresponds to (12.8±3.2)% of the b[`(b)]b\bar{b} production. We find that (23±6)% of the unaccounted events contain additional muon candidates. For comparison, this fraction is (6.9±0.4)% for events due to b[`(b)]b\bar{b} production.
  European Physical Journal C 05/2012; 71(8):1-14. · 3.63 Impact Factor
• Source

  Available from: Manuel Mussini

  Article: Search for narrow resonances lighter than ϒ mesons

  CDF Collaboration, T. Aaltonen, J. Adelman, T. Akimoto, B. Álvarez González, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, [......], T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, L. Zanello, A. Zanetti, X. Zhang, Y. Zheng, S. Zucchelli
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  ABSTRACT: We report a search for narrow resonances, produced in p[`(p)]p\bar{p} collisions at Ös=1.96\sqrt{s}=1.96 TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0GeV/c 2. The data, collected with the CDFII detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630pb−1. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the ϒ(1S) meson.
  European Physical Journal C 04/2012; 62(2):319-326. · 3.63 Impact Factor
• Article: Measurements of the angular distributions in the decays B→K(*)μ(+)μ(-) at CDF.

  T Aaltonen, B Alvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: We report an indirect search for nonstandard model physics using the flavor-changing neutral current decays B→K(*)μ(+)μ(-). We reconstruct the decays and measure their angular distributions, as a function of q(2)=M(μμ)(2)c(2), where M(μμ) is the dimuon mass, in pp¯ collisions at √s=1.96 TeV using a data sample corresponding to an integrated luminosity of 6.8 fb(-1). The transverse polarization asymmetry A(T)(2) and the time-reversal-odd charge-and-parity asymmetry A(im) are measured for the first time, together with the K* longitudinal polarization fraction F(L) and the muon forward-backward asymmetry A(FB) for the decays B(0)→K(*0)μ(+)μ(-) and B(+)→K(*+)μ(+)μ(-). The B→K*μ(+)μ(-) forward-backward asymmetry in the most sensitive kinematic regime, 1≤q(2)<6 GeV(2)/c(2), is measured to be A(FB)=0.29(-0.23)(+0.20)(stat)±0.07(syst), the most precise result to date. No deviations from the standard model predictions are observed.
  Physical Review Letters 02/2012; 108(8):081807. · 7.37 Impact Factor
• Article: Search for the rare radiative decay W→πγ in pp̅ collisions at √s=1.96 TeV

  T. Aaltonen, B. Álvarez González, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We present a search for the rare radiative decay W±→π±γ using data corresponding to an integrated luminosity of 4.3 fb-1 of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF experiment at Fermilab. As no statistically significant signal is observed, we set a 95%-confidence-level upper limit on the relative branching fraction Γ(W±→π±γ)/Γ(W±→e±ν) at 6.4×10-5, a factor of 10 improvement over the previous limit.
  Phys. Rev. D. 02/2012; 85(3).
• Article: Search for heavy metastable particles decaying to jet pairs in pp̅ collisions at √s=1.96 TeV

  T. Aaltonen, B. Álvarez González, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: A search is performed for heavy metastable particles that decay into jet pairs with a macroscopic lifetime (cτ∼1 cm) in pp̅ collisions at √s=1.96 TeV using data from the CDF II detector at Fermilab corresponding to an integrated luminosity of 3.2 fb-1. To estimate the standard model background, a data-driven approach is used. Probability-density functions are constructed to model secondary vertices from known processes. No statistically significant excess is observed above the background. Limits on the production cross section in a hidden valley benchmark phenomenology are set for various Higgs boson masses as well as metastable particle masses and lifetimes.
  Phys. Rev. D. 01/2012; 85(1).
• Source

  Available from: Manuel Mussini

  Article: Search for a low mass Standard Model Higgs boson in the tau-tau decay channel in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV

  CDF Collaboration, T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: We report on a search for the standard model Higgs boson decaying into pairs of tau leptons in $p\bar{p}$ collisions produced by the Tevatron at $\sqrt{s}$ = 1.96 TeV. The analyzed data sample was recorded by the CDFII detector and corresponds to an integrated luminosity of 6.0 fb$^{-1}$. The search is performed in the final state with one tau decaying leptonically and the second one identified through its semi-hadronic decay.Since no significant excess is observed, a 95% credibility level upper limit on the production cross section times branching ratio to the tau-tau final state is set for hypothetical Higgs boson masses between 100 and 150 GeV/$c^2$. For a Higgs boson of 120 GeV/$c^2$ the observed (expected) limit is 14.6 (15.3) the predicted value.
  01/2012;
• Source

  Available from: Manuel Mussini

  Article: Search for a Higgs boson in the diphoton final state in pp collisions at sqrt[s]=1.96  TeV.

  T Aaltonen, B Alvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 7.0  fb{-1} of integrated luminosity from pp collisions at sqrt[s]=1.96  TeV collected by the CDF experiment. No evidence of such a resonance is observed, and upper limits are set on the cross section times branching ratio of the resonant state as a function of Higgs boson mass. The limits are interpreted in the context of the standard model and one fermiophobic benchmark model where the data exclude fermiophobic Higgs bosons with masses below 114  GeV/c{2} at a 95% Bayesian credibility level.
  Physical Review Letters 01/2012; 108(1):011801. · 7.37 Impact Factor
• Article: Search for WZ+ZZ production with missing transverse energy+jets with b enhancement at √s=1.96 TeV

  T. Aaltonen, B. Álvarez González, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: Diboson production (WW+WZ+ZZ) has been observed at the Tevatron in hadronic decay modes dominated by the WW process. This paper describes the measurement of the cross section of WZ and ZZ events in final states with large E̸T and using b-jet identification as a tool to suppress WW contributions. Because of the limited energy resolution, we cannot distinguish between partially hadronic decays of WZ and ZZ, and we measure the sum of these processes. The number of signal events is extracted using a simultaneous fit to the invariant mass distribution of the two jets for events with two b-jet candidates and events with fewer than two b-jet candidates. We measure a cross section σ(pp̅ →WZ,ZZ)=5.8-3.0+3.6 pb, in agreement with the standard model.
  Phys. Rev. D. 01/2012; 85(1).
• Article: Measurement of the B(s)0 lifetime in fully and partially reconstructed B(s)0→D(s)(-)(ϕπ(-))X decays in p¯p collisions at √s=1.96 TeV.

  T Aaltonen, B Alvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: We present a measurement of the B(s)(0) lifetime in fully and partially reconstructed B(s)(0)→D(s)(-)(ϕπ(-))X decays in 1.3  fb(-1) collected in pp ¯ collisions at √s=1.96 TeV by the CDF II detector at the Fermilab Tevatron. We measure τ(B(s)(0))=1.518±0.041(stat)±0.027(syst)  ps. The ratio of this result and the world average B(0) lifetime yields τ(B(s)(0))/τ(B(0))=0.99±0.03, which is in agreement with recent theoretical predictions.
  Physical Review Letters 12/2011; 107(27):272001. · 7.37 Impact Factor
• Article: Measurement of polarization and search for CP violation in B(s)0→φφ decays.

  T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: We present the first measurement of polarization and CP-violating asymmetries in a B(s)(0) decay into two light vector mesons, B(s)(0)→φφ, and an improved determination of its branching ratio using 295 decays reconstructed in a data sample corresponding to 2.9 fb(-1) of integrated luminosity collected by the CDF experiment at the Fermilab Tevatron collider. The fraction of longitudinal polarization is determined to be f(L)=0.348±0.041(stat)±0.021(syst), and the branching ratio B(B(s)(0)→φφ)=[2.32±0.18(stat)±0.82(syst)]×10(-5). Asymmetries of decay angle distributions sensitive to CP violation are measured to be A(u)=-0.007±0.064(stat)±0.018(syst) and A(v)=-0.120±0.064(stat)±0.016(syst).
  Physical Review Letters 12/2011; 107(26):261802. · 7.37 Impact Factor
• Article: Search for a heavy toplike quark in pp collisions at √s=1.96 TeV.

  T Aaltonen, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, G Apollinari, J A Appel, A Apresyan, [......], J Yoh, K Yorita, T Yoshida, G B Yu, I Yu, S S Yu, J C Yun, A Zanetti, Y Zeng, S Zucchelli
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  ABSTRACT: We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in pp collisions at √s=1.96 TeV. We perform parallel searches for t'→Wb and t'→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t' quark mass, we set upper limits on the t't' production cross section and exclude a standard model fourth-generation t' quark decaying to Wb (Wq) with mass below 358 (340) GeV/c(2) at 95% C.L.
  Physical Review Letters 12/2011; 107(26):261801. · 7.37 Impact Factor
• Source

  Available from: Manuel Mussini

  Article: Search for Standard Model Higgs Boson Production in Association with a W Boson Using a Matrix Element Technique at CDF in p-bar{p} Collisions at sqrt{s} = 1.96 TeV

  CDF Collaboration, T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: This paper presents a search for standard model Higgs boson production in association with a $W$ boson using events recorded by the CDF experiment in a dataset corresponding to an integrated luminosity of 5.6 fb-1. The search is performed using a matrix element technique in which the signal and background hypotheses are used to create a powerful discriminator. The discriminant output distributions for signal and background are fit to the observed events using a binned likelihood approach to search for the Higgs boson signal. We find no evidence for a Higgs boson, and 95% confidence level (C.L.) upper limits are set on the Higgs boson production rate. The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between 100 and 150 GeV. The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.
  12/2011;
• Source

  Available from: Manuel Mussini

  Article: Measurement of ZZ production in leptonic final states at {\surd}s of 1.96 TeV at CDF

  T. Aaltonen, B. Alvarez Gonzalez, S. Amerio, D. Amidei, A. Anastassov, A. Annovi, J. Antos, G. Apollinari, J. A. Appel, A. Apresyan, [......], J. Yoh, K. Yorita, T. Yoshida, G. B. Yu, I. Yu, S. S. Yu, J. C. Yun, A. Zanetti, Y. Zeng, S. Zucchelli
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  ABSTRACT: In this paper we present a precise measurement of the total ZZ production cross section in pp collisions at {\surd}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 (llvv) decay modes of the Z. The combined measured cross section for pp {\to} ZZ is 1.64^(+0.44)_(-0.38) pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.
  12/2011;