-
J.A. Aguilar,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar,
M. Ardid,
A.C. Assis Jesus,
T. Astraatmadja, [......],
G. Vannoni,
M. Vecchi,
P. Vernin,
G. Wijnker,
J. Wilms,
E. de Wolf,
H. Yepes,
D. Zaborov,
J.D. Zornoza,
J. Zúñiga
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2012; · 1.21 Impact Factor
-
S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
J. Nielsen,
Y.B. Pan,
J.H. von Wimmersperg-Toeller,
W. Wiedenmann,
J. Wu,
Sau Lan Wu,
X. Wu,
G. Zobernig,
G. Dissertori,
The ALEPH Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A search for Higgs bosons produced in association with a fermion pair, and decaying to WW, is performed with the data collected
by the ALEPH detector at centre-of-mass energies ranging from 191 to 209GeV. The data correspond to an integrated luminosity
of 453.2pb-1. Thirteen exclusive selections are developed according to the different final state topologies. No statistically significant
evidence for a Higgs boson decaying into a WW pair has been found. An upper limit is derived, as a function of the Higgs boson
mass, on the product of the e+e-→Hff̄ cross section and the H→WW branching ratio. The data on the search for H→WW are combined with previously published ALEPH
results on the search for H→γγ, to significantly extend the limits on the mass of a fermiophobic Higgs boson.
European Physical Journal C 04/2012; 49(2):439-455. · 3.63 Impact Factor
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S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
J. Nielsen,
Y.B. Pan,
J.H. von Wimmersperg-Toeller,
W. Wiedenmann,
J. Wu,
S.L. Wu,
X. Wu,
G. Zobernig,
G. Dissertori,
The ALEPH Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Hadronic Z decays into three jets are used to test QCD models of colour reconnection (CR). A sensitive quantity is the rate
of gluon jets with a gap in the particle rapidity distribution and zero jet charge. Gluon jets are identified by either energy-ordering
or by tagging two b-jets. The rates predicted by two string-based tunable CR models, one implemented in JETSET (the GAL model),
the other in ARIADNE, are too high and disfavoured by the data, whereas the rates from the corresponding non-CR standard versions
of these generators are too low. The data can be described by the GAL model assuming a small value for the R0 parameter in the range 0.01-0.02.
European Physical Journal C 04/2012; 48(3):685-698. · 3.63 Impact Factor
-
S. Schael,
R. Barate,
R. Brunelière,
I. De Bonis,
D. Decamp,
C. Goy,
S. Jézéquel,
J.-P. Lees,
F. Martin,
E. Merle, [......],
G.W. Wilson,
J.A. Wilson,
T.R. Wyatt,
S. Yamashita,
D. Zer-Zion,
L. Zivkovic,
S. Heinemeyer,
A. Pilaftsis,
G. Weiglein,
The LEP Working Group for Higgs Boson Searches
[show abstract]
[hide abstract]
ABSTRACT: The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by
the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined
for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no
significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper
bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number
of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large
exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses
of neutral Higgs bosons.
European Physical Journal C 04/2012; 47(3):547-587. · 3.63 Impact Factor
-
V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
M Aoki, [......],
H Yin,
K Yip,
S W Youn,
T Zhao,
T G Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the W boson mass using data corresponding to 4.3 fb(-1) of integrated luminosity collected with the D0 detector during Run II at the Fermilab Tevatron pp collider. With a sample of 1,677,394 W → eν candidate events, we measure M(W) = 80.367 ± 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1 fb(-1) of integrated luminosity, to yield M(W) = 80.375 ± 0.023 GeV.
Physical Review Letters 04/2012; 108(15):151804. · 7.37 Impact Factor
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S. Adrián-Martínez,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar,
M. Ardid,
A.C. Assis Jesus,
T. Astraatmadja, [......],
M. Vecchi,
P. Vernin,
S. Wagner,
G. Wijnker,
J. Wilms,
E. de Wolf,
H. Yepes,
D. Zaborov,
J.D. Zornoza,
J. Zúñiga
Astroparticle Physics 04/2012; · 3.22 Impact Factor
-
V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
M Aoki, [......],
Z Ye,
H Yin,
K Yip,
S W Youn,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by the D0 detector at a pp center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R(-1)>260 GeV in a minimal UED model.
Physical Review Letters 03/2012; 108(13):131802. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
J Alimena,
G Alkhazov,
A Alton,
G Alverson, [......],
H Yin,
K Yip,
S W Youn,
J Yu,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for charged massive long-lived particles (CMLLPs), based on 5.2 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp collider. We search for events in which one or more particles are reconstructed as muons but have speed and ionization energy loss (dE/dx) inconsistent with muons produced in beam collisions. CMLLPs are predicted in several theories of physics beyond the standard model. We exclude pair-produced long-lived gauginolike charginos below 267 GeV and Higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar top quarks with mass below 285 GeV.
Physical Review Letters 03/2012; 108(12):121802. · 7.37 Impact Factor
-
M. Ageron,
J.A. Aguilar,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar,
M. Ardid,
A.C. Assis Jesus, [......],
G. Vannoni,
M. Vecchi,
P. Vernin,
G. Wijnker,
J. Wilms,
E. de Wolf,
H. Yepes,
D. Zaborov,
J.D. Zornoza,
J. Zúñiga
Astroparticle Physics 03/2012; · 3.22 Impact Factor
-
V. M. Abazov,
B. Abbott,
B. S. Acharya,
M. Adams,
T. Adams,
G. D. Alexeev,
G. Alkhazov,
A. Alton,
G. Alverson,
G. A. Alves, [......],
H. Yin,
K. Yip,
S. W. Youn,
J. Yu,
T. Zhao,
B. Zhou,
J. Zhu,
M. Zielinski,
D. Zieminska,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of pp̅ →Zγ→ℓ+ℓ-γ (ℓ=e, μ) production with a data sample corresponding to an integrated luminosity of 6.2 fb-1 collected by the D0 detector at the Fermilab Tevatron pp̅ Collider. The results of the electron and muon channels are combined, and we measure the total production cross section and the differential cross section dσ/dpTγ, where pTγ is the momentum of the photon in the plane transverse to the beam line. The results obtained are consistent with the standard model predictions from next-to-leading order calculations. We use the transverse momentum spectrum of the photon to place limits on anomalous ZZγ and Zγγ couplings.
Phys. Rev. D. 02/2012; 85(5).
-
The CDF,
Collaborations: T. Aaltonen,
V. M. Abazov,
B. Abbott,
B. S. Acharya,
M. Adams,
T. Adams,
G. D. Alexeev,
G. Alkhazov,
A. Alton, [......],
J. C. Yun,
A. Zanetti,
Y. Zeng,
T. Zhao,
B. Zhou,
J. Zhu,
M. Zielinski,
D. Zieminska,
L. Zivkovic,
S. Zucchelli
[show abstract]
[hide abstract]
ABSTRACT: We report the combination of recent measurements of the helicity of the W
boson from top quark decay by the CDF and D0 collaborations, based on data
samples corresponding to integrated luminosities of 2.7 - 5.4 fb^-1 of ppbar
collisions collected during Run II of the Fermilab Tevatron Collider. Combining
measurements that simultaneously determine the fractions of W bosons with
longitudinal (f0) and right-handed (f+) helicities, we find f0 = 0.722 \pm
0.081 [\pm 0.062 (stat.) \pm 0.052 (syst.)] and f+ = -0.033 \pm 0.046 [\pm
0.034 (stat.) \pm 0.031 (syst.)]. Combining measurements where one of the
helicity fractions is fixed to the value expected in the standard model, we
find f0 = 0.682 \pm 0.057 [\pm 0.035 (stat.) \pm 0.046 (syst.)] and f+ =
-0.015\pm0.035 [\pm 0.018 (stat.) \pm 0.030 (syst.)]. The results are
consistent with standard model expectations.
02/2012;
-
V. M. Abazov,
B. Abbott,
B. S. Acharya,
M. Adams,
T. Adams,
G. D. Alexeev,
G. Alkhazov,
A. Alton,
G. Alverson,
G. A. Alves, [......],
K. Yip,
S. W. Youn,
J. Yu,
S. Zelitch,
T. Zhao,
B. Zhou,
J. Zhu,
M. Zielinski,
D. Zieminska,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We report an updated measurement of the CP-violating phase, ϕsJ/ψϕ, and the decay-width difference for the two mass eigenstates, ΔΓs, from the flavor-tagged decay Bs0→J/ψϕ. The data sample corresponds to an integrated luminosity of 8.0 fb-1 accumulated with the D0 detector using pp̅ collisions at √s=1.96 TeV produced at the Fermilab Tevatron collider. The 68% Bayesian credibility intervals, including systematic uncertainties, are ΔΓs=0.163-0.064+0.065 ps-1 and ϕsJ/ψϕ=-0.55-0.36+0.38. The p-value for the Standard Model point is 29.8%.
Phys. Rev. D. 02/2012; 85(3).
-
S. Adrián-Martínez,
M. Ageron,
J. A. Aguilar,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar,
M. Ardid, [......],
M. Vecchi,
P. Vernin,
S. Wagner,
G. Wijnker,
J. Wilms,
E. de Wolf,
H. Yepes,
D. Zaborov,
J. D. Zornoza,
J. Zúñiga
[show abstract]
[hide abstract]
ABSTRACT: The ANTARES neutrino telescope, located 40km off the coast of Toulon in the
Mediterranean Sea at a mooring depth of about 2475m, consists of twelve
detection lines equipped typically with 25 storeys. Every storey carries three
optical modules that detect Cherenkov light induced by charged secondary
particles (typically muons) coming from neutrino interactions. As these lines
are flexible structures fixed to the sea bed and held taut by a buoy, sea
currents cause the lines to move and the storeys to rotate. The knowledge of
the position of the optical modules with a precision better than 10cm is
essential for a good reconstruction of particle tracks. In this paper the
ANTARES positioning system is described. It consists of an acoustic positioning
system, for distance triangulation, and a compass-tiltmeter system, for the
measurement of the orientation and inclination of the storeys. Necessary
corrections are discussed and the results of the detector alignment procedure
are described.
02/2012;
-
Collaboration,
V. M. Abazov,
B. Abbott,
B. S. Acharya,
M. Adams,
T. Adams,
G. D. Alexeev,
G. Alkhazov,
A. Alton,
G. Alverson, [......],
Z. Ye,
H. Yin,
K. Yip,
S. W. Youn,
T. Zhao,
B. Zhou,
J. Zhu,
M. Zielinski,
D. Zieminska,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for the pair production of scalar top quarks
($\tilde{t}_{1}$), the lightest supersymmetric partners of the top quarks, in
$p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using data
corresponding to an integrated luminosity of {7.3 $fb^{-1}$} collected with the
\dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is
assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino
($\tilde{\nu}$). We investigate final states arising from $\tilde{t}_{1}
\bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu}$ and
$\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu}
\tilde{\nu}$. With no significant excess of events observed above the
background expected from the standard model, we set exclusion limits on this
production process in the ($m_{\tilde{t}_{1}}$,$m_{\tilde{\nu}}$) plane.
02/2012;
-
S. Adrián-Martínez,
J.A. Aguilar,
I. Al Samarai,
A. Albert,
M. André,
M. Anghinolfi,
G. Anton,
S. Anvar,
M. Ardid,
A.C. Assis Jesus, [......],
M. Vecchi,
P. Vernin,
S. Wagner,
G. Wijnker,
J. Wilms,
E. de Wolf,
H. Yepes,
D. Zaborov,
J.D. Zornoza,
J. Zúñiga
Astroparticle Physics 02/2012; · 3.22 Impact Factor
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J. Aguilar,
P. Ambalathankandy,
T. Fiutowski,
M. Idzik,
Sz. Kulis,
D. Przyborowski,
K. Swientek,
A. Bamberger,
M. Köhli,
M. Lupberger, [......],
D. Haas,
M. Pohl,
R. Diener,
P. Fischer,
I. Peric,
A. Kaukher,
O. Schäfer,
H. Schröder,
R. Wurth,
A. F. Zarnecki
[show abstract]
[hide abstract]
ABSTRACT: The EUDET-project was launched to create an infrastructure for developing and
testing new and advanced detector technologies to be used at a future linear
collider. The aim was to make possible experimentation and analysis of data for
institutes, which otherwise could not be realized due to lack of resources. The
infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.
01/2012;
-
V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
H Yin,
K Yip,
S W Youn,
J Yu,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the ratio of events with correlated t and t ̅t spins to the total number of t ̅t events. This ratio f is evaluated using a matrix-element-based approach in 729 t ̅t candidate events with a single lepton ℓ (electron or muon) and at least four jets. The analyzed p ̅p collisions data correspond to an integrated luminosity of 5.3 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider operating at a center-of-mass energy √s=1.96 TeV. Combining this result with a recent measurement of f in dileptonic final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in t ̅t events with a significance of more than 3 standard deviations.
Physical Review Letters 01/2012; 108(3):032004. · 7.37 Impact Factor
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V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a search for pair production of doubly charged Higgs bosons in the processes qq¯→H(++)H(--) decaying through H(±±)→τ(±)τ(±),μ(±)τ(±),μ(±)μ(±). The search is performed in pp¯ collisions at a center-of-mass energy of √s = 1.96 TeV using an integrated luminosity of up to 7.0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C.L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(±±) branching fractions. Models predicting different H(±±) decays are investigated. Assuming B(H(±±)→τ(±)τ(±))=1 yields an observed (expected) lower limit on the mass of a left-handed H(L)(±±) boson of 128 (116) GeV and assuming B(H(±±)→μ(±)τ(±))=1 the corresponding limits are 144 (149) GeV. In a model with B(H(±±)→τ(±)τ(±))=B(H(±±)→μ(±)τ(±))=B(H(±±)→μ(±)μ(±))=1/3, we obtain M(H(L)(±±))>130 (138) GeV.
Physical Review Letters 01/2012; 108(2):021801. · 7.37 Impact Factor
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V. M. Abazov,
B. Abbott,
B. S. Acharya,
M. Adams,
T. Adams,
G. D. Alexeev,
G. Alkhazov,
A. Alton,
G. Alverson,
G. A. Alves, [......],
K. Yip,
S. W. Youn,
J. Yu,
S. Zelitch,
T. Zhao,
B. Zhou,
J. Zhu,
M. Zielinski,
D. Zieminska,
L. Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of forward-backward asymmetry in top quark-antiquark production in proton-antiproton collisions in the final state containing a lepton and at least four jets. Using a data set corresponding to an integrated luminosity of 5.4 fb-1, collected by the D0 experiment at the Fermilab Tevatron Collider, we measure the tt̅ forward-backward asymmetry to be (9.2±3.7)% at the reconstruction level. When corrected for detector acceptance and resolution, the asymmetry is found to be (19.6±6.5)%. We also measure a corrected asymmetry based on the lepton from a top quark decay, found to be (15.2±4.0)%. The results are compared to predictions based on the next-to-leading-order QCD generator mc@nlo. The sensitivity of the measured and predicted asymmetries to the modeling of gluon radiation is discussed.
Phys. Rev. D. 12/2011; 84(11).
-
V M Abazov,
B Abbott,
B S Acharya,
M Adams,
T Adams,
G D Alexeev,
G Alkhazov,
A Alton,
G Alverson,
G A Alves, [......],
K Yip,
S W Youn,
J Yu,
S Zelitch,
T Zhao,
B Zhou,
J Zhu,
M Zielinski,
D Zieminska,
L Zivkovic
[show abstract]
[hide abstract]
ABSTRACT: We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W(→lν) + γ production in eγ and μγ final states. Using data corresponding to an integrated luminosity of 4.2 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp → Wγ + X → lνγ + X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WWγ couplings for data from hadron colliders: -0.4<Δκ(γ)<0.4 and -0.08<λ(γ)<0.07 at the 95% C.L.
Physical Review Letters 12/2011; 107(24):241803. · 7.37 Impact Factor
