-
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,
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: The azimuthal anisotropy of charged particles in Pb-Pb collisions at sqrt[s_{NN}]=2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (p_{T}) range up to approximately 60 GeV/c. The data cover both the low-p_{T} region associated with hydrodynamic flow phenomena and the high-p_{T} region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v_{2}) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v_{2} values are found to first increase with p_{T}, reaching a maximum around p_{T}=3 GeV/c, and then to gradually decrease to almost zero, with the decline persisting up to at least p_{T}=40 GeV/c over the full centrality range measured.
Physical Review Letters 07/2012; 109(2):022301. · 7.37 Impact Factor
-
S. CMS Collaboration 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 neutral Higgs bosons decaying to tau pairs at a
center-of-mass energy of 7 TeV is performed using a dataset
corresponding to an integrated luminosity of 4.6 fb-1
recorded by the CMS experiment at the LHC. The search is sensitive to
both the standard model Higgs boson and to the neutral Higgs bosons
predicted by the minimal supersymmetric extension of the standard model
(MSSM). No excess of events is observed in the tau-pair invariant-mass
spectrum. For a standard model Higgs boson in the mass range of
110-145 GeV upper limits at 95% confidence level (CL) on the
production cross section are determined. We exclude a Higgs boson with
mH=115 GeV with a production cross section 3.2 times of
that predicted by the standard model. In the MSSM, upper limits on the
neutral Higgs boson production cross section times branching fraction to
tau pairs, as a function of the pseudoscalar Higgs boson mass,
mA, sets stringent new bounds in the parameter space,
excluding at 95% CL values of tan β as low as 7.1 at
mA=160 GeV in the mhmax benchmark scenario.
Physics Letters B 05/2012; 713:68-90. · 3.95 Impact Factor
-
The CMS Collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A measurement of the t[`(t)]\mathrm{t{\bar{t}}} production cross section in proton-proton collisions at a centre-of-mass energy of 7TeV has been performed at the LHC with
the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36pb−1 and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three
or more hadronic jets. The kinematic properties of the events are used to separate the t[`(t)]\mathrm{t{\bar{t}}} signal from W+jets and QCD multijet background events. The measured cross section is 173+39-32(stat. + syst.)173^{+39}_{-32}~(\mathrm{stat}. + \mathrm{syst}.)pb, consistent with standard model expectations.
European Physical Journal C 05/2012; 71(9):1-27. · 3.63 Impact Factor
-
The CMS Collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse
momentum, using a data sample corresponding to an integrated luminosity of 36 pb−1 collected in proton-proton collisions at Ös = 7 \sqrt {s} = 7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which
are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the
standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected
particle and one or two jets.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(8):1-46. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The first measurement of inclusive Z → τ
+
τ
− production in pp collisions at the LHC is presented, in the final states μ + hadrons, e + hadrons, e + μ, and μ + μ. The data sample corresponds to an integrated luminosity of 36 pb−1 collected with the CMS detector. The measured cross section is σ (pp → ZX) × B (Z → τ
+
τ
−) = 1.00 ± 0.05(stat.) ± 0.08(syst.) ± 0.04(lumi.)nb, which is in good agreement with the next-to-next-to-leading order QCD prediction and improves on previous measurements
in the Z → e+e− and μ
+
μ
− channels. The reconstruction efficiency for hadronic τ decays is determined with a precision of 7%.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(8):1-32. · 5.83 Impact Factor
-
The CMS Collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A measurement of the underlying activity in events with a jet of transverse momentum in the several GeV region is performed
in proton-proton collisions at Ös = 0.9 \sqrt {s} = 0.9 and 7 TeV, using data collected by the CMS experiment at the LHC. The production of charged particles with pseudorapidity
|η| < 2 and transverse momentum p
T
> 0.5GeV/c is studied in the azimuthal region transverse to that of the leading set of charged particles forming a track-jet. A significant
growth of the average multiplicity and scalar-p
T
sum of the particles in the transverse region is observed with increasing p
T
of the leading track-jet, followed by a much slower rise above a few GeV/c. For track-jet p
T
larger than a few GeV/c, the activity in the transverse region is approximately doubled with a centre-of-mass energy increase
from 0.9 to 7 TeV. Predictions of several QCD-inspired models as implemented in pythia are compared to the data.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(9):1-31. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search is performed for an excess of events, over the standard model expectations, with a photon, a lepton, and large missing
transverse energy in pp collisions at Ös = 7 \sqrt {s} = 7 TeV. Such events are expected in many new physics models, in particular a supersymmetric theory that is broken via a gauge-mediated
mechanism, when the lightest charged and neutral gauginos are mass degenerate. The data sample used in this search corresponds
to an integrated luminosity of 35 pb-1 collected with the CMS detector at the LHC. No evidence of such an excess above the standard model backgrounds, dominated
by W production, is found. The results are presented as 95% confidence level upper limits on the cross section for a benchmark
gauge-mediated scenario, and are then converted into exclusion limits on the squark, gluino, and wino masses.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(6):1-28. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for narrow resonances at high mass in the dimuon and dielectron channels has been performed by the CMS experiment
at the CERN LHC, using pp collision data recorded at Ös = 7 \sqrt {s} = 7 TeV. The event samples correspond to integrated luminosities of 40 pb−1 in the dimuon channel and 35 pb−1 in the dielectron channel. Heavy dilepton resonances are predicted in theoretical models with extra gauge bosons (Z′) or
as Kaluza-Klein graviton excitations (GKK) in the Randall-Sundrum model. Upper limits on the inclusive cross section of Z′(GKK) → ℓ
+
ℓ
− relative to Z → ℓ
+
ℓ
− are presented. These limits exclude at 95% confidence level a Z′ with standard-model-like couplings below 1140GeV, the superstring-inspired
Z
ψ
′ below 887 GeV, and, for values of the coupling parameter
k /
[`(M)] \textPl {{k} \left/ {{{{\overline M }_{\text{Pl}}}}} \right.} of 0.05 (0.1), Kaluza-Klein gravitons below 855 (1079) GeV.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(5):1-35. · 5.83 Impact Factor
-
The CMS Collaboration,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan,
M. Friedl, [......],
D. Lomidze,
R. Loveless,
A. Mohapatra,
W. Parker,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The production of J/ψ mesons is studied in pp collisions at Ös = 7\sqrt{s} = 7TeV with the CMS experiment at the LHC. The measurement is based on a dimuon sample corresponding to an integrated luminosity
of 314nb−1. The J/ψ differential cross section is determined, as a function of the J/ψ transverse momentum, in three rapidity ranges. Afit to the decay length distribution is used to separate the prompt from
the non-prompt (b hadron toJ/ψ) component. Integrated over J/ψ transverse momentum from6.5 to 30GeV/c and over rapidity in the range |y|<2.4, the measured cross sections, times the dimuon decay branching fraction, are 70.9±2.1(stat.)±3.0(syst.)±7.8(luminosity)nb
for prompt J/ψ mesons assuming unpolarized production and 26.0±1.4(stat.)±1.6(syst.)±2.9(luminosity)nb for J/ψ mesons from b-hadron decays.
European Physical Journal C 04/2012; 71(3):1-26. · 3.63 Impact Factor
-
The CMS collaboration,
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,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: Bose-Einstein correlations between identical particles are measured in samples of proton-proton collisions at 0.9 and 7 TeV
centre-of-mass energies, recorded by the CMS experiment at the LHC. The signal is observed in the form of an enhancement of
number of pairs of same-sign charged particles with small relative momentum. The dependence of this enhancement on kinematic
and topological features of the event is studied. Anticorrelations between same-sign charged particles are observed in the
region of relative momenta higher than those in the signal region.
KeywordHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(5):1-29. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
I. Ojalvo,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A measurement of inclusive W and Z production cross sections in pp collisions at Ös = 7 \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 pb−1. The measured inclusive cross sections are σ(pp → WX) ×
B( \textW ® ln ) \mathcal{B}\left( {{\text{W}} \to \ell \nu } \right) = 10.31 ± 0.02 (stat.) ± 0.09 (syst.) ± 0.10 (th.) ± 0.41 (lumi.) nb and σ(pp → ZX) ×
B( \textZ ® l+ l- ) \mathcal{B}\left( {{\text{Z}} \to {\ell^{+} }{\ell^{-} }} \right) = 0.974 ± 0.007 (stat.) ± 0.007 (syst.) ± 0.018 (th.) ± 0.039 (lumi.) nb, limited to the dilepton invariant mass range 60 to 120GeV. The luminosity-independent cross section ratios
are (σ(pp → WX) ×
B( \textW ® ln ) \mathcal{B}\left( {{\text{W}} \to \ell \nu } \right) /(σ(pp → ZX) ×
B( \textZ ® l+ l- ) \mathcal{B}\left( {{\text{Z}} \to {\ell^{+} }{\ell^{-} }} \right) = 10.54 ± 0.07 (stat.) ± 0.08 (syst.) ± 0.16 (th.) and (σ(pp → W+
X) ×
B( \textW + ® l+ n ) \mathcal{B}\left( {{{\text{W}}^{ + }} \to {\ell^{+} }\nu } \right) /(σ(pp → W−
X) ×
B( \textW- ® l- [`(n)] ) \mathcal{B}\left( {{{\text{W}}^{-} } \to {\ell^{-} }\bar{\nu }} \right) = 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.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(10):1-76. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The results of searches for new physics in events with two same-sign isolated leptons, hadronic jets, and missing transverse
energy in the final state are presented. The searches use an integrated luminosity of 35 pb−1 of pp collision data at a centre-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. The observed numbers
of events agree with the standard model predictions, and no evidence for new physics is found. To facilitate the interpretation
of our data in a broader range of new physics scenarios, information on our event selection, detector response, and efficiencies
is provided.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(6):1-47. · 5.83 Impact Factor
-
The CMS collaboration,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan,
M. Friedl, [......],
D. Lomidze,
R. Loveless,
A. Mohapatra,
W. Parker,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton
collisions at centre-of-mass energies of Ös = 0.9 \sqrt {s} = 0.9 , 2.36, and 7 TeV, in five pseudorapidity ranges from |η| < 0.5 to |η| < 2.4. The data were collected with the minimum-bias trigger of the CMS experiment during the LHC commissioning runs in 2009 and
the 7 TeV run in 2010. The multiplicity distribution at
Ös = 0.9\textTeV \sqrt {s} = 0.9\;{\text{TeV}} is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with Ös \sqrt {s} is underestimated by most event generators. The average transverse momentum as a function of the multiplicity is also presented.
The measurement of higher-order moments of the multiplicity distribution confirms the violation of Koba-Nielsen-Olesen scaling
that has been observed at lower energies.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(1):1-38. · 5.83 Impact Factor
-
CMS collaboration,
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,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at
centre-of-mass energies of 0.9 and 7 TeV. The
\textK\textS0 {\text{K}}_{\text{S}}^0 , Λ, and Ξ− particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as
functions of rapidity and transverse momentum, p
T. The results are compared to other experiments and to predictions of the Pythia Monte Carlo program. The p
T distributions are found to differ substantially from the Pythia results and the production rates exceed the predictions by up to a factor of three.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(5):1-40. · 5.83 Impact Factor
-
CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for large extra spatial dimensions via virtual-graviton exchange in the diphoton channel has been carried out with
the CMS detector at the LHC. No excess of events above the standard model expectations is found using a data sample collected
in proton-proton collisions at Ös = 7 \sqrt {s} = 7 TeV and corresponding to an integrated luminosity of 36 pb−
1. New lower limits on the effective Planck scale in the range of 1.6–2.3TeV at the 95% confidence level are set, providing
the most restrictive bounds to date on models with more than two large extra dimensions.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(5):1-28. · 5.83 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
C. Lazaridis,
J. Leonard,
R. Loveless,
A. Mohapatra,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search is presented for physics beyond the standard model (SM) in final states with opposite-sign isolated lepton pairs
accompanied by hadronic jets and missing transverse energy. The search is performed using LHC data recorded with the CMS detector,
corresponding to an integrated luminosity of 34 pb−1. No evidence for an event yield beyond SM expectations is found. An upper limit on the non-SM contribution to the signal
region is deduced from the results. This limit is interpreted in the context of the constrained minimal supersymmetric model.
Additional information is provided to allow testing the exclusion of specific models of physics beyond the SM.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(6):1-33. · 5.83 Impact Factor
-
The CMS Collaboration,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan,
M. Friedl, [......],
J. Leonard,
D. Lomidze,
R. Loveless,
A. Mohapatra,
G. Polese,
D. Reeder,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A measurement of the underlying activity in scattering processes with p
T
scale in the GeV region is performed in proton–proton collisions at Ös = 0.9\sqrt{s} = 0.9TeV, using data collected by the CMS experiment at the LHC. Charged particle production is studied with reference to the
direction of a leading object, either a charged particle or a set of charged particles forming a jet. Predictions of several
QCD-inspired models as implemented in PYTHIA are compared, after full detector simulation, to the data. The models generally
predict too little production of charged particles with pseudorapidity |η|<2, p
T
>0.5 GeV/c, and azimuthal direction transverse to that of the leading object.
European Physical Journal C 04/2012; 70(3):555-572. · 3.63 Impact Factor
-
The CMS collaboration,
S. Chatrchyan,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan, [......],
J. Leonard,
R. Loveless,
A. Mohapatra,
F. Palmonari,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for groups of collimated muons is performed using a data sample collected by the CMS experiment at the LHC, at a
centre-of-mass energy of 7TeV, and corresponding to an integrated luminosity of 35 pb−1. The analysis searches for production of new low-mass states decaying into pairs of muons and is designed to achieve high
sensitivity to a broad range of models predicting leptonic jet signatures. With no excess observed over the background expectation,
upper limits on the production cross section times branching fraction times acceptance areset, ranging from 0.1 to 0.5 pb
at the 95% CL depending on event topology. In addition, the results are interpreted in several benchmark models in the context
of supersymmetry with a new light dark sector exploring previously inaccessible parameter space.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(7):1-34. · 5.83 Impact Factor
-
The CMS collaboration,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
C. Fabjan,
M. Friedl, [......],
D. Lomidze,
R. Loveless,
A. Mohapatra,
W. Parker,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: Measurements of inclusive W and Z boson production cross sections in pp collisions at Ös = 7 \sqrt {s} = 7 TeV are presented, based on 2.9 pb−1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are
combined to give
s( \textpp ® \textWX ) B( \textW ® ln ) = 9.95±0.07( \textstat. )±0.28( \textsyst. )±1.09 \sigma \left( {{\text{pp}} \to {\text{W}}X} \right) \times \mathcal{B}\left( {{\text{W}} \to \ell \nu } \right) = 9.95\pm 0.07\left( {{\text{stat}}{.}} \right)\pm 0.28\left( {{\text{syst}}{.}} \right)\pm 1.09 (lumi.) nb and
s( \textpp ® \textZX ) B( Z ® l+ l- ) = 0.931±0.026( \textstat. )±0.023( \textsyst. )±0.102 \sigma \left( {{\text{pp}} \to {\text{Z}}X} \right) \times \mathcal{B}\left( {Z \to {\ell^{+} }{\ell^{-} }} \right) = 0.931\pm 0.026\left( {{\text{stat}}{.}} \right)\pm 0.023\left( {{\text{syst}}{.}} \right)\pm 0.102 (lumi.) nb, where ℓ stands for either e or μ. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions,
are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty
of less than 4%, are also reported.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(1):1-40. · 5.83 Impact Factor
