-
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
-
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
-
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, [......],
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
-
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: A search is performed in pp collisions at sqrt[s]=7 TeV for exotic particles decaying via WZ to final states with electrons and muons. The data sample corresponds to an integrated luminosity of approximately 5 fb^{-1}. No significant excess is observed in the data above the expected standard model background. Upper bounds at 95% confidence level are set on the production cross section of the W^{'} boson described by the sequential standard model and on the W^{'} WZ coupling. W^{'} bosons with masses below 1143 GeV are excluded. Limits are also set in the context of low-scale technicolor models, under a range of assumptions concerning the model parameters.
Physical Review Letters 10/2012; 109(14):141801. · 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, [......],
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
-
[show abstract]
[hide abstract]
ABSTRACT: Purpose: Evaluate the dosimetric impact of daily setup error and inter-fraction organ motion on the radiation treatment plan. Methods: Twelve patients undergoing definitive IMRT treatments for prostate cancer were evaluated. All patients underwent fiducial marker placement prior to treatment planning CT scan, and were treated to a dose of 8100cGy given in 45 fractions. We retrospectively created a plan for each treatment day that had a shift available. To calculate the dose the patient would have received with no setup correction, we mathematically 'negated' the shift by moving the isocenter in the opposite direction of the shift. The individualized daily plans were combined to generate an overall plan sum. The dose distribution from these uncorrected plans was compared to the actual treatment plans. Results: A total of 390 shifts were negated and their corresponding plans evaluated. The mean isocenter shift based on the location of the fiducial markers was 3.3±6.5mm to the right, 1.6±5.1mm posteriorly, and 1.0±5.0mm along the caudal direction. The mean D95 dose when setup error was corrected and uncorrected for the PTV8100 volume was 8089cGy and 7303cGy (p < 0.001) and for prostate volume was 8228cGy and 7844cGy (p < 0.002). The mean V95 values when setup error was corrected and uncorrected for the PTV8100 volume was 99.9% vs. 87.3% (p < 0.0001). At an individual level, the difference in D95 value approached 1200cGy for the prostate volume and 2000cGy for the PTV8100 volume. There was no statistically significant difference in the D35 parameter for the surrounding normal tissue except for the dose received by the right hip and the penile bulb. Conclusion: This work indicates that significant underdosing, approaching 2000cGy for the PTV8100 volume, can occur as a Result of inaccurate patient setup, and emphasizes the importance of accurate patient setup and target localization.
Medical Physics 06/2012; 39(6):3699. · 2.83 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Purpose: To evaluate the dosimetry of 3D CRT, Step-and-Shoot Intensity Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT) treatment plans with respect to doses to the carotid arteries and spinal cord. Methods: Data from ten patients who underwent CT scanning for treatment planning was selected for this retrospective study. The spinal cord, carotid arteries, and tissue of neck not involving the target volume called Non-Target-Volume (NTV), and clinical target volumes (CTVs) were contoured. A margin added to the CTVs generated planning target volumes (PTVs). Using 6 MV photon beams, treatment plans with 3-D CRT, IMRT, and VMAT techniques were created for each patient. The prescription dose was 63 Gy in 28 fractions. The evaluation was based on the averaged results of mean doses to PTV, mean doses and doses to the 20% (D20), 50% (D50), and 90% (D90) of the volume of the carotid arteries, and maximum doses to the spinal cord for all three treatment delivery techniques. Results: Mean doses to PTV were 64.12, 66.44, and 65.64 Gy for 3D CRT, IMRT and VMAT plans respectively. Mean doses to the NTV, were 1.42, 0.91, and 0.94 Gy, to the carotid arteries were 55.23, 31.31, 23.32 Gy, and maximum doses to spinal cord were 2.99, 25.72 and 25.75 Gy, for 3D CRT, IMRT and VMAT plans respectively. The D20, D50, and D90 doses to carotid arteries were 63.23, 62.01, and 30.51 Gy, for 3D CRT, 47.64, 35.54, and 3.47 Gy for IMRT, 36.23, 24.30, and 3.13 Gy for VMAT plans respectively. Conclusions: All three techniques achieved conformal doses to the PTV. Doses to spinal cord were lower with 3D CRT technique, but doses to the carotid arteries were substantially reduced with VMAT plans. This is important to minimize the risk of atherogenesis and consequent cerebrovascular complications.
Medical Physics 06/2012; 39(6):3709. · 2.83 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 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
-
D. Akimov,
T. Alexander,
D. Alton,
K. Arisaka,
H. O. Back,
P. Beltrame,
J. Benziger,
A. Bolozdynya,
G. Bonfini,
A. Brigatti, [......],
H. Wang,
S. Westerdale,
M. Wojcik,
A. Wright,
J. Xu,
C. Yang,
S. Zavatarelli,
M. Zehfus,
W. Zhong,
G. Zuzel
[show abstract]
[hide abstract]
ABSTRACT: As part of the DarkSide program of direct dark matter searches using liquid
argon TPCs, a prototype detector with an active volume containing 10 kg of
liquid argon, DarkSide-10, was built and operated underground in the Gran Sasso
National Laboratory in Italy. A critically important parameter for such devices
is the scintillation light yield, as photon statistics limits the rejection of
electron-recoil backgrounds by pulse shape discrimination. We have measured the
light yield of DarkSide-10 using the readily-identifiable full-absorption peaks
from gamma ray sources combined with single-photoelectron calibrations using
low-occupancy laser pulses. For gamma lines of energies in the range 122-1275
keV, we get consistent light yields averaging 8.887\pm0.003(stat)\pm0.444(sys)
p.e./keV_ee. With additional purification, the light yield measured at 511 keV
increased to 9.142\pm0.006(stat) p.e./keV_ee.
04/2012;
-
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,
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,
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,
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,
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
-
[show abstract]
[hide abstract]
ABSTRACT: A glasshouse experiment was set up to compare processes and organisms in two soils planted with genetically modified (GM)
herbicide tolerant (HT) maize treated with appropriate herbicides. This was part of a wider project (ECOGEN) looking at the
consequences of GM cropping systems on soil biology using a tiered approach at laboratory, glasshouse and field scales. Soil
for the experiment was taken from field sites where the same maize cultivars were grown to allow comparison between results
under glasshouse and field conditions. The maize cultivars T25 (GM HT glufosinate-ammonium tolerant), Orient (non HT near
isogenic control for T25) and Monumental (a conventional, non HT variety) were grown in contrasting sandy loam and clay loam
soils, half were sprayed with the appropriate herbicide as used in the field and soil samples were taken at the five-leaf
and flowering plant growth stage. The main effects on all measured parameters were those of soil type and plant growth stage,
with four categories of subsequent interaction: (1) there were no effects of herbicide on plant growth or soil microarthropods:
(2) the maize cultivar (but not the GM HT trait) had effects on the decomposition of cotton strips and the nematode community;
(3) herbicide application in general altered the community level physiological profile of the microbial community and reduced
both soil basal respiration and the abundance of protozoa; and (4) the specific application of glufosinate-ammonium to T25
maize altered soil microbial community structure measured by ester linked fatty acids. The results from this glasshouse experiment
support the findings from the field that there are effects of herbicide application on the soil microbial and meso-faunal
community but that, compared to other standard agricultural practices, the differences are relatively small.
Plant and Soil 04/2012; 308(1):93-103. · 2.73 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 lepton charge asymmetry in inclusive pp → WX production at
Ös = 7\textTeV \sqrt {s} = 7\;{\text{TeV}} is presented based on data recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 36 pb−1. This high precision measurement of the lepton charge asymmetry, performed in both the W → eν and W → μν channels, provides new insights into parton distribution functions.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(4):1-31. · 5.83 Impact Factor
