-
CDF Collaboration,
T. Aaltonen,
S. Amerio,
D. Amidei, A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari,
J. A. Appel,
T. Arisawa, [......],
K. Yi,
J. Yoh,
K. Yorita,
T. Yoshida,
G. B. Yu,
I. Yu,
A. M. Zanetti,
Y. Zeng,
C. Zhou,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report on a measurement of the top-quark electric charge in ttbar events
in which one W boson originating from the top-quark pair decays into leptons
and the other into hadrons. The event sample was collected by the CDF II
detector in sqrt(s)=1.96 TeV proton-antiproton collisions and corresponds to
5.6 fb^(-1). We find the data to be consistent with the standard model and
exclude the existence of an exotic quark with -4/3 electric charge and mass of
the conventional top quark at the 99% confidence level.
04/2013;
-
T Aaltonen,
S Amerio,
D Amidei, A Anastassov,
A Annovi,
J Antos,
G Apollinari,
J A Appel,
T Arisawa,
A Artikov, [......],
K Yi,
J Yoh,
K Yorita,
T Yoshida,
G B Yu,
I Yu,
A M Zanetti,
Y Zeng,
C Zhou,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: This Letter reports a measurement of the cross section for producing pairs of central prompt isolated photons in proton-antiproton collisions at a total energy sqrt[s]=1.96 TeV using data corresponding to 9.5 fb^{-1} integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured differential cross section is compared to three calculations derived from the theory of strong interactions. These include a prediction based on a leading order matrix element calculation merged with a parton shower model, a next-to-leading order calculation, and a next-to-next-to-leading order calculation. The first and last calculations reproduce most aspects of the data, thus showing the importance of higher-order contributions for understanding the theory of strong interaction and improving measurements of the Higgs boson and searches for new phenomena in diphoton final states.
Physical Review Letters 03/2013; 110(10):101801. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
R Loveless,
A Mohapatra,
M U Mozer,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb^{-1}, collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2±0.6(stat)±0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.
Physical Review Letters 02/2013; 110(8):081803. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a τ lepton and a b quark. The search is based on a data sample of pp collisions at sqrt[s]=7 TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8 fb^{-1}. The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a τ lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, τ lepton, and b quark, λ_{333}^{'} are obtained. These results are the most stringent for these scenarios to date.
Physical Review Letters 02/2013; 110(8):081801. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
C Lazaridis,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at sqrt[s]=7 TeV, using a data sample of Υ(nS)→μ^{+}μ^{-} decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb^{-1}. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λ_{ϑ}, λ_{φ}, and λ_{ϑφ}, as well as the frame-invariant quantity λ[over ˜], are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.
Physical Review Letters 02/2013; 110(8):081802. · 7.37 Impact Factor
-
D. Abbaneo,
G. Abbiendi,
M. Abbrescia,
S. Abdullin,
A. Abdulsalam,
B.S. Acharya,
D. Acosta,
J.G. Acosta,
A. Adair,
W. Adam, [......],
G. Bagliesi,
Y. Bai,
D. Bailleux,
P. Baillon,
R. Bainbridge,
H. Bakhshiansohi,
M.N. Bakirci,
J.A. Bakken,
M. Balazs,
B. Baldin
-
D. Abbaneo,
G. Abbiendi,
M. Abbrescia,
S. Abdullin,
A. Abdulsalam,
B.S. Acharya,
D. Acosta,
J.G. Acosta,
A. Adair,
W. Adam, [......],
G. Bagliesi,
Y. Bai,
D. Bailleux,
P. Baillon,
R. Bainbridge,
H. Bakhshiansohi,
M.N. Bakirci,
J.A. Bakken,
M. Balazs,
B. Baldin
-
CDF Collaboration,
T. Aaltonen,
S. Amerio,
D. Amidei, A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari,
J. A. Appel,
T. Arisawa, [......],
K. Yi,
J. Yoh,
K. Yorita,
T. Yoshida,
G. B. Yu,
I. Yu,
A. M. Zanetti,
Y. Zeng,
C. Zhou,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present an updated search for the Higgs boson produced in association with
a vector boson in the final state with missing transverse energy and two jets.
We use the full CDF data set corresponding to an integrated luminosity of 9.45
fb${}^{-1}$ at a proton-antiproton center-of-mass energy of $\sqrt{s}=1.96$
TeV. New to this analysis is the inclusion of a $b$-jet identification
algorithm specifically optimized for $H\to b\bar{b}$ searches. Across the Higgs
boson mass range $90 \le m_H \le 150$ GeV$/c^2$, the expected 95% credibility
level upper limits on the $V H$ production cross section times the $H\to
b\bar{b}$ branching fraction are improved by an average of 14% relative to the
previous analysis. At a Higgs boson mass of 125 GeV$/c^2$, the observed
(expected) limit is 3.06 (3.33) times the standard model prediction,
corresponding to one of the most sensitive searches to date in this final
state.
01/2013;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Evidence is presented for the associated production of a single top quark and W boson in pp collisions at sqrt[s]=7 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 4.9 fb^{-1}. The measurement is performed using events with two leptons and a jet originated from a b quark. A multivariate analysis based on kinematic properties is utilized to separate the tt[over ¯] background from the signal. The observed signal has a significance of 4.0σ and corresponds to a cross section of 16_{-4}^{+5} pb, in agreement with the standard model expectation of 15.6±0.4_{-1.2}^{+1.0} pb.
Physical Review Letters 01/2013; 110(2):022003. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
C Lazaridis,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a search for heavy, right-handed muon neutrinos, N_{μ}, and right-handed W_{R} bosons, which arise in the left-right symmetric extensions of the standard model. The analysis is based on a 5.0 fb^{-1} sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected by the CMS detector at the Large Hadron Collider. No evidence is observed for an excess of events over the standard model expectation. For models with exact left-right symmetry, heavy right-handed neutrinos are excluded at 95% confidence level for a range of neutrino masses below the W_{R} mass, dependent on the value of M_{W_{R}}. The excluded region in the two-dimensional (M_{W_{R}}, M_{N_{μ}}) mass plane extends to M_{W_{R}}=2.5 TeV.
Physical Review Letters 12/2012; 109(26):261802. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: We report an investigation of the invariant mass spectrum of the two jets with highest transverse momentum in pp→W+2-jet and W+3-jet events to look for resonant enhancement. The data sample corresponds to an integrated luminosity of 5.0 fb^{-1} collected with the CMS detector at sqrt[s]=7 TeV. We find no evidence for the anomalous structure reported by the CDF Collaboration, and establish an upper limit of 5.0 pb at 95% confidence level on the production cross section for a generic Gaussian signal with mass near 150 GeV. Additionally, we exclude two theoretical models that predict a CDF-like dijet resonance near 150 GeV.
Physical Review Letters 12/2012; 109(25):251801. · 7.37 Impact Factor
-
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
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: The suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 μb^{-1} and 230 nb^{-1}, respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76 TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression of the Υ(nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, R_{AA}, is measured as a function of the collision centrality. Integrated over centrality, the R_{AA} values are 0.56±0.08(stat)±0.07(syst), 0.12±0.04(stat)±0.02(syst), and lower than 0.10 (at 95% confidence level), for the Υ(1S), Υ(2S), and Υ(3S) states, respectively. The results demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies.
Physical Review Letters 11/2012; 109(22):222301. · 7.37 Impact Factor
-
T Aaltonen,
B Alvarez González,
S Amerio,
D Amidei, A Anastassov,
A Annovi,
J Antos,
G Apollinari,
J A Appel,
T Arisawa, [......],
K Yorita,
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
A Zanetti,
Y Zeng,
C Zhou,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present the first direct measurement of the top-quark mass using tt[over ¯] events decaying in the hadronic τ+jets decay channel. Using data corresponding to an integrated luminosity of 2.2 fb^{-1} collected by the CDF II detector in pp[over ¯] collisions at sqrt[s]=1.96 TeV at the Fermilab Tevatron, we measure the tt[over ¯] cross section, σ_{tt[over ¯]}, and the top-quark mass, M_{top}. We extract M_{top} from a likelihood based on per-event probabilities calculated with leading-order signal and background matrix elements. We measure σ_{tt[over ¯]}=8.8±3.3(stat)±2.2(syst) pb and M_{top}=172.7±9.3(stat)±3.7(syst) GeV/c^{2}.
Physical Review Letters 11/2012; 109(19):192001. · 7.37 Impact Factor
-
CDF Collaboration,
T. Aaltonen,
S. Amerio,
D. Amidei, A. Anastassov,
A. Annovi,
J. Antos,
G. Apollinari,
J. A. Appel,
T. Arisawa, [......],
K. Yi,
J. Yoh,
K. Yorita,
T. Yoshida,
G. B. Yu,
I. Yu,
A. M. Zanetti,
Y. Zeng,
C. Zhou,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We present new measurements of the inclusive forward-backward ttbar
production asymmetry, AFB, and its dependence on several properties of the
ttbar system. The measurements are performed with the full Tevatron data set
recorded with the CDF II detector during ppbar collisions at sqrt(s) = 1.96
TeV, corresponding to an integrated luminosity of 9.4 fb^(-1). We measure the
asymmetry using the rapidity difference Delta-y=y_(t)-y_(tbar). Parton-level
results are derived, yielding an inclusive asymmetry of 0.164+/-0.047 (stat +
syst). We observe a linear dependence of AFB on the top-quark pair mass
M(ttbar) and the rapidity difference |Delta-y| at detector and parton levels.
Assuming the standard model, the probabilities to observe the measured values
or larger for the detector-level dependencies are 7.4*10^(-3) and 2.2*10^(-3)
for M(ttbar) and |Delta-y| respectively. Lastly, we study the dependence of the
asymmetry on the transverse momentum of the ttbar system at the detector level.
These results are consistent with previous lower-precision measurements and
provide additional quantification of the functional dependencies of the
asymmetry.
11/2012;
-
T Aaltonen,
B Alvarez González,
S Amerio,
D Amidei, A Anastassov,
A Annovi,
J Antos,
G Apollinari,
J A Appel,
T Arisawa, [......],
K Yorita,
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
A Zanetti,
Y Zeng,
C Zhou,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: A search is presented for the standard model Higgs boson produced in association with top quarks using the full Run II proton-antiproton collision data set, corresponding to 9.45 fb^{-1}, collected by the Collider Detector at Fermilab. No significant excess over the expected background is observed, and 95% credibility-level upper bounds are placed on the cross section σ(tt[over ¯]H→lepton+missing transverse energy+jets). For a Higgs boson mass of 125 GeV/c^{2}, we expect to set a limit of 12.6 and observe a limit of 20.5 times the standard model rate. This represents the most sensitive search for a standard model Higgs boson in this channel to date.
Physical Review Letters 11/2012; 109(18):181802. · 7.37 Impact Factor
-
T Aaltonen,
B Alvarez González,
S Amerio,
D Amidei, A Anastassov,
A Annovi,
J Antos,
G Apollinari,
J A Appel,
T Arisawa, [......],
K Yorita,
T Yoshida,
G B Yu,
I Yu,
S S Yu,
J C Yun,
A Zanetti,
Y Zeng,
C Zhou,
S Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report a measurement of the bottom-strange meson mixing phase β_{s} using the time evolution of B_{s}^{0}→J/ψ(→μ^{+}μ^{-})ϕ(→K^{+}K^{-}) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt[s]=1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb^{-1} of integrated luminosity. We report confidence regions in the two-dimensional space of β_{s} and the B_{s}^{0} decay-width difference ΔΓ_{s} and measure β_{s}∈[-π/2,-1.51]∪[-0.06,0.30]∪[1.26,π/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of β_{s}, we also determine ΔΓ_{s}=0.068±0.026(stat)±0.009(syst) ps^{-1} and the mean B_{s}^{0} lifetime τ_{s}=1.528±0.019(stat)±0.009(syst) ps, which are consistent and competitive with determinations by other experiments.
Physical Review Letters 10/2012; 109(17):171802. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan,
M Friedl, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: A search for physics beyond the standard model is performed in events with at least three jets and large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of sqrt[s]=7 TeV. No significant excess of events above the expected backgrounds is observed in 4.98 fb^{-1} of data collected with the CMS detector at the Large Hadron Collider. The results are presented in the context of the constrained minimal supersymmetric extension of the standard model and more generically for simplified models. For the simplified models of gluino-gluino and squark-squark production, gluino masses below 1.0 TeV and squark masses below 0.76 TeV are excluded in case the lightest supersymmetric particle mass is below 200 GeV. These results significantly extend previous searches.
Physical Review Letters 10/2012; 109(17):171803. · 7.37 Impact Factor
-
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
[show abstract]
[hide abstract]
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;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan,
M Friedl, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: The transverse energy (E_{T}) in Pb-Pb collisions at 2.76 TeV nucleon-nucleon center-of-mass energy (sqrt[s_{NN}]) has been measured over a broad range of pseudorapidity (η) and collision centrality by using the CMS detector at the LHC. The transverse energy density per unit pseudorapidity (dE_{T}/dη) increases faster with collision energy than the charged particle multiplicity. This implies that the mean energy per particle is increasing with collision energy. At all pseudorapidities, the transverse energy per participating nucleon increases with the centrality of the collision. The ratio of transverse energy per unit pseudorapidity in peripheral to central collisions varies significantly as the pseudorapidity increases from η=0 to |η|=5.0. For the 5% most central collisions, the energy density per unit volume is estimated to be about 14 GeV/fm^{3} at a time of 1 fm/c after the collision. This is about 100 times larger than normal nuclear matter density and a factor of 2.6 times higher than the energy density reported at sqrt[s_{NN}]=200 GeV at the Relativistic Heavy Ion Collider.
Physical Review Letters 10/2012; 109(15):152303. · 7.37 Impact Factor
