-
D. Abbaneo,
G. Abbiendi,
M. Abbrescia,
S. Abdullin,
A. Abdulsalam,
B.S. Acharya,
D. Acosta,
J.G. Acosta,
A. Adair,
W. Adam, [......],
M.H. Zoeller,
O. Zorba,
P. Zotto,
W. Zou,
G. Zumerle,
M. Zupan,
A. Zuranski,
R. Zuyeuski,
M. Zvada,
P. Zych
[show abstract]
[hide abstract]
ABSTRACT: The Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and
has been the subject of numerous searches at accelerators around the world. Its discovery would verify the existence of a
complex scalar field thought to give mass to three of the carriers of the electroweak force—the W+, W–, and Z0 bosons—as well as to the fundamental quarks and leptons. The CMS Collaboration has observed, with a statistical significance
of five standard deviations, a new particle produced in proton-proton collisions at the Large Hadron Collider at CERN. The
evidence is strongest in the diphoton and four-lepton (electrons and/or muons) final states, which provide the best mass resolution
in the CMS detector. The probability of the observed signal being due to a random fluctuation of the background is about 1
in 3 × 106. The new particle is a boson with spin not equal to 1 and has a mass of about 1.25 giga–electron volts. Although its measured
properties are, within the uncertainties of the present data, consistent with those expected of the Higgs boson, more data
are needed to elucidate the precise nature of the new particle.
Science 12/2012; 338(6114):1569-1575. · 31.20 Impact Factor
-
The CDF Collaboration,
T. Aaltonen,
J. Adelman,
B. Álvarez González,
S. Amerio,
D. Amidei,
A. Anastassov,
J. Antos,
G. Apollinari,
A. Apresyan, [......],
Y. C. Yang,
K. Yorita,
T. Yoshida,
G. B. Yu,
I. Yu,
S. S. Yu,
J. C. Yun,
A. Zanetti,
X. Zhang,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDFII
detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates
are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor
production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in
which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDFII detector,
trigger, and event reconstruction.
European Physical Journal C 04/2012; 68(1):109-118. · 3.63 Impact Factor
-
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
[show abstract]
[hide abstract]
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
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan,
M Friedl, [......],
C Lazaridis,
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: A search for a Higgs boson in the four-lepton decay channel H→ZZ, with each Z boson decaying to an electron or muon pair, is reported. The search covers Higgs boson mass hypotheses in the range of 110<m(H)<600 GeV. The analysis uses data corresponding to an integrated luminosity of 4.7 fb(-1) recorded by the CMS detector in pp collisions at √s=7 TeV from the LHC. Seventy-two events are observed with four-lepton invariant mass m(4ℓ)>100 GeV (with 13 below 160 GeV), while 67.1±6.0 (9.5±1.3) events are expected from background. The four-lepton mass distribution is consistent with the expectation of standard model background production of ZZ pairs. Upper limits at 95% confidence level exclude the standard model Higgs boson in the ranges of 134-158 GeV, 180-305 GeV, and 340-465 GeV. Small excesses of events are observed around masses of 119, 126, and 320 GeV, making the observed limits weaker than expected in the absence of a signal.
Physical Review Letters 03/2012; 108(11):111804. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t{1}) decaying to a b quark and a chargino χ{1}{±} with a subsequent χ{1}{±} decay into a neutralino χ{1}{0}, lepton ℓ, and neutrino ν. Using a data sample corresponding to 2.7 fb{-1} of integrated luminosity of pp collisions at sqrt[s]=1.96 TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and t{1}t{1} signal. We find no evidence for t{1}t{1} production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B(χ{1}{±}→χ{1}{0}ℓ{±}ν).
Physical Review Letters 06/2010; 104(25):251801. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: The cross section for jets from b quarks produced with a W boson has been measured in pp collision data from 1.9 fb(-1) of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74+/-0.27(stat)+/-0.42(syst) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.
Physical Review Letters 04/2010; 104(13):131801. · 7.37 Impact Factor
-
T. Aaltonen,
J. Adelman,
T. Akimoto,
B. Álvarez González,
S. Amerio,
D. Amidei,
A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari, [......],
T. Yoshida,
G. B. Yu,
I. Yu,
S. S. Yu,
J. C. Yun,
L. Zanello,
A. Zanetti,
X. Zhang,
Y. Zheng,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present three measurements of the top-quark mass in the lepton plus jets channel with approximately 1.9 fb-1 of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of b-tagged jets to determine a top-quark mass of 166.9-8.5+9.5(stat)±2.9(syst) GeV/c2, and another the transverse momentum of electrons and muons from W-boson decays to determine a top-quark mass of 173.5-8.9+8.8(stat)±3.8(syst) GeV/c2. These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of 170.7±6.3(stat)±2.6(syst) GeV/c2.
Phys. Rev. D. 02/2010; 81(3).
-
T Aaltonen,
J Adelman,
T Akimoto,
M G Albrow,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos, [......],
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
I Zaw,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: A combined mass and particle identification fit is used to make the first observation of the decay B(s)(0) --> D(s)(+/-)K(-/+) and measure the branching fraction of B(s)(0) --> D(s)(+/-)K(-/+) relative to B(s)(0) --> D(s)(+)pi(-). This analysis uses 1.2 fb(-1) integrated luminosity of pp collisions at square root(s) = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron collider. We observe a B(s)(0) --> D(s)(+/-)K(-/+) signal with a statistical significance of 8.1 sigma and measure B(B(s)(0) --> D(s)(+/-)K(-/+) /B(B(s)(0) --> D(s)(+)pi(-) 0.097+/-0.018(stat) +/- 0.009(syst).
Physical Review Letters 11/2009; 103(19):191802. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using 1.8 fb(-1) of integrated luminosity of pp collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of tanbeta versus m(A) (the ratio of the vacuum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).
Physical Review Letters 11/2009; 103(20):201801. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
M G Albrow,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos, [......],
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
I Zaw,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for the standard-model Higgs boson in pp collisions at square root(s) = 1.96 TeV using an integrated luminosity of 2.0 fb(-1). We look for production of the Higgs boson decaying to a pair of bottom quarks in association with a vector boson V (W or Z) decaying to quarks, resulting in a four-jet final state. Two of the jets are required to have secondary vertices consistent with B-hadron decays. We set the first 95% confidence level upper limit on the VH production cross section with V(--> qq/qq')H(--> bb) decay for Higgs boson masses of 100-150 GeV/c2 using data from run II at the Fermilab Tevatron. For m(H) = 120 GeV/c2, we exclude cross sections larger than 38 times the standard-model prediction.
Physical Review Letters 11/2009; 103(22):221801. · 7.37 Impact Factor
-
T. Aaltonen,
J. Adelman,
T. Akimoto,
B. Álvarez González,
S. Amerio,
D. Amidei,
A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari, [......],
T. Yoshida,
G. B. Yu,
I. Yu,
S. S. Yu,
J. C. Yun,
L. Zanello,
A. Zanetti,
X. Zhang,
Y. Zheng,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of the bottom, doubly-strange baryon Ωb- through the decay chain Ωb-→J/ψΩ-, where J/ψ→μ+μ-, Ω-→ΛK-, and Λ→pπ-, using 4.2 fb-1 of data from pp̅ collisions at √s=1.96 TeV, and recorded with the Collider Detector at Fermilab. A signal is observed whose probability of arising from a background fluctuation is 4.0×10-8, or 5.5 Gaussian standard deviations. The Ωb- mass is measured to be 6054.4±6.8(stat)±0.9(syst) MeV/c2. The lifetime of the Ωb- baryon is measured to be 1.13-0.40+0.53(stat)±0.02(syst) ps. In addition, for the Ξb- baryon we measure a mass of 5790.9±2.6(stat)±0.8(syst) MeV/c2 and a lifetime of 1.56-0.25+0.27(stat)±0.02(syst) ps. Under the assumption that the Ξb- and Ωb- are produced with similar kinematic distributions to the Λb0 baryon, we find σ(Ξb-)B(Ξb-→J/ψΞ-)/σ(Λb0)B(Λb0→J/ψΛ)=0.167-0.025+0.037(stat)±0.012(syst) and σ(Ωb-)B(Ωb-→J/ψΩ-)/σ(Λb0)B(Λb0→J/ψΛ)=0.045-0.012+0.017(stat)± 0.004(syst) for baryons produced with transverse momentum in the range of 6–20 GeV/c.
Phys. Rev. D. 10/2009; 80(7).
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present an analysis of the mass of the X(3872) reconstructed via its decay to J/psi pi(+)pi(-) using 2.4 fb(-1) of integrated luminosity from pp collisions at square root(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The possible existence of two nearby mass states is investigated. Within the limits of our experimental resolution the data are consistent with a single state, and having no evidence for two states we set upper limits on the mass difference between two hypothetical states for different assumed ratios of contributions to the observed peak. For equal contributions, the 95% confidence level upper limit on the mass difference is 3.6 MeV/c(2). Under the single-state model the X(3872) mass is measured to be 3871.61+/-0.16(stat)+/-0.19(syst) MeV/c(2), which is the most precise determination to date.
Physical Review Letters 10/2009; 103(15):152001. · 7.37 Impact Factor
-
T. Aaltonen,
J. Adelman,
T. Akimoto,
B. Álvarez González,
S. Amerio,
D. Amidei,
A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari, [......],
T. Yoshida,
G. B. Yu,
I. Yu,
S. S. Yu,
J. C. Yun,
L. Zanello,
A. Zanetti,
X. Zhang,
Y. Zheng,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present a signature-based search for the anomalous production of events containing a photon, two jets, of which at least one is identified as originating from a b quark, and missing transverse energy (E̸T). The search uses data corresponding to 2.0 fb-1 of integrated luminosity from pp̅ collisions at a center-of-mass energy of √s=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. From 6.697 47×106 events with a photon candidate with transverse energy ET>25 GeV, we find 617 events with E̸T>25 GeV and two or more jets with ET>15 GeV, at least one identified as originating from a b quark, versus an expectation of 607±113 events. Increasing the requirement on E̸T to 50 GeV, we find 28 events versus an expectation of 30±11 events. We find no indications of non-standard-model phenomena.
Phys. Rev. D. 09/2009; 80(5).
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb(-1) of integrated luminosity of pp collision data taken at square root s = 1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 and 150 GeV/c(2). Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c(2).
Physical Review Letters 09/2009; 103(10):101802. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report on the first direct search for charged Higgs bosons decaying into cs in tt events produced by pp collisions at square root s = 1.96 TeV. The search uses a data sample corresponding to an integrated luminosity of 2.2 fb(-1) collected by the CDF II detector at Fermilab and looks for a resonance in the invariant mass distribution of two jets in the lepton + jets sample of tt candidates. We observe no evidence of charged Higgs bosons in top quark decays. Hence, 95% upper limits on the top quark decay branching ratio are placed at B(t --> H(+)b)< 0.1 to 0.3 for charged Higgs boson masses of 60 to 150 GeV/c(2) assuming B(H(+) --> cs)=1.0. The upper limits on B(t --> H(+)b) are also used as model-independent limits on the decay branching ratio of top quarks to generic scalar charged bosons beyond the standard model.
Physical Review Letters 09/2009; 103(10):101803. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of single top-quark production using 3.2 fb(-1) of pp[over ] collision data with sqrt[s]=1.96 TeV collected by the Collider Detector at Fermilab. The significance of the observed data is 5.0 standard deviations, and the expected sensitivity for standard model production and decay is in excess of 5.9 standard deviations. Assuming m(t) = 175 GeV/c(2), we measure a cross section of 2.3(-0.5);(+0.6)(stat + syst) pb, extract the CKM matrix-element value |V(tb)| = 0.91 + or - 0.11(stat + syst) + or - 0.07(theory), and set the limit |V(tb)| > 0.71 at the 95% C.L.
Physical Review Letters 08/2009; 103(9):092002. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: A search for a narrow diphoton mass resonance is presented based on data from 3.0 fb;{-1} of integrated luminosity from pp[over ] collisions at sqrt[s] = 1.96 TeV collected by the CDF experiment. No evidence of a resonance in the diphoton mass spectrum is observed, and upper limits are set on the cross section times branching fraction of the resonant state as a function of Higgs boson mass. The resulting limits exclude Higgs bosons with masses below 106 GeV/c;{2} at a 95% Bayesian credibility level for one fermiophobic benchmark model.
Physical Review Letters 08/2009; 103(6):061803. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present the first observation in hadronic collisions of the electroweak production of vector boson pairs (VV, V = W, Z) where one boson decays to a dijet final state. The data correspond to 3.5 fb(-1) of integrated luminosity of pp[over ] collisions at sqrt[s] = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We observe 1516 + or - 239(stat) + or - 144(syst) diboson candidate events and measure a cross section sigma(pp[over ]-->VV + X) of 18.0 + or - 2.8(stat) + or - 2.4(syst) + or -1.1(lumi) pb, in agreement with the expectations of the standard model.
Physical Review Letters 08/2009; 103(9):091803. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We performed a signature-based search for long-lived charged massive particles produced in 1.0 fb-1 of pp[over ] collisions at sqrt[s]=1.96 TeV, collected with the CDF II detector using a high transverse-momentum (pT) muon trigger. The search used time of flight to isolate slowly moving, high-pT particles. One event passed our selection cuts with an expected background of 1.9+/-0.2 events. We set an upper bound on the production cross section and, interpreting this result within the context of a stable scalar top-quark model, set a lower limit on the particle mass of 249 GeV/c2 at 95% C.L.
Physical Review Letters 08/2009; 103(2):021802. · 7.37 Impact Factor
-
T Aaltonen,
J Adelman,
T Akimoto,
B Alvarez González,
S Amerio,
D Amidei,
A Anastassov,
A Annovi,
J Antos,
G Apollinari, [......],
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
L Zanello,
A Zanetti,
X Zhang,
Y Zheng,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We search for new charmless decays of neutral b hadrons to pairs of charged hadrons, using 1 fb(-1) of data collected by the CDF II detector at the Fermilab Tevatron. We report the first observation of the Bs0-->K-pi+ decay and measure B(Bs0-->K-pi+)=(5.0+/-0.7(stat)+/-0.8(syst))x10(-6). We also report the first observation of charmless b-baryon decays, and measure B(Lambdab0-->ppi-)=(3.5+/-0.6(stat)+/-0.9(syst))x10(-6) and B(Lambdab0-->pK-)=(5.6+/-0.8(stat)+/-1.5(syst))x10(-6). No evidence is found for other modes, and we set the limit B(Bs0-->pi+pi;-)<1.2x10(-6) at 90% C.L.
Physical Review Letters 07/2009; 103(3):031801. · 7.37 Impact Factor
