-
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: A measurement of the b-hadron production cross section in proton-proton collisions at
Ös = 7\textTeV \sqrt {s} = 7\;{\text{TeV}} is presented. The dataset, corresponding to 85 nb−1, was recorded with the CMS experiment at the LHC using a low-threshold single-muon trigger. Events are selected by the presence
of a muon with transverse momentum $ p_T^\mu > 6\;{\text{GeV}} $ p_T^\mu > 6\;{\text{GeV}} with respect to the beam direction and pseudorapidity |η
μ
| < 2.1. The transverse momentum of the muon with respect to the closest jet discriminates events containing b hadrons from
background. The inclusive b-hadron production cross section is presented as a function of muon transverse momentum and pseudorapidity.
The measured total cross section in the kinematic acceptance is σ(pp → b + X → μ + X′) = 1.32 ± 0.01(stat) ± 0.30(syst) ± 0.15(lumi)μb.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(3):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, [......],
J. Leonard,
D. Lomidze,
R. Loveless,
A. Mohapatra,
D. Reeder,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The result of a search at the LHC for heavy stable charged particles produced in pp collisions at
Ös = 7\textTeV \sqrt {s} = 7\;{\text{TeV}} is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb−1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with
heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same
signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398GeV/c
2, using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon
detectors. A lower limit of 311 GeV/c
2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this
particle becomes neutral before reaching the muon detectors.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(3):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,
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
-
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 t[`(t)] {{\rm t}\bar{\rm t}} production cross section and top quark mass are measured in proton-proton collisions at Ös = 7 \sqrt {s} = 7 TeV in a data sample corresponding to an integrated luminosity of 36 pb−1 collected by the CMS experiment. The measurements are performed in events with two leptons (electrons or muons) in the final
state. Results of the cross section measurement in events with and without b-quark identification are obtained and combined.
The measured value is
\upsigmat[`(t)] {\upsigma_{{{\rm t}\bar{\rm t}}}} = 168 ± 18 (stat.) ± 14 (syst.) ± 7 (lumi.) pb, consistent with predictions from the standard model. The top quark mass m
top is reconstructed with two different methods, a full kinematic analysis and a matrix weighting technique. The combination
yields a measurement of m
top = 175.5 ± 4.6 (stat.) ± 4.6 (syst.) GeV/c
2.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(7):1-49. · 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: A measurement of the angular correlations between beauty and anti-beauty hadrons (
\textB[`(\textB)] {\text{B}}\overline {\text{B}} ) produced in pp collisions at a centre-of-mass energy of 7 TeV at the CERN LHC is presented, probing for the first time the
region of small angular separation. The B hadrons are identified by the presence of displaced secondary vertices from their
decays. The B hadron angular separation is reconstructed from the decay vertices and the primary-interaction vertex. The differential
\textB[`(\textB)] {\text{B}}\overline {\text{B}} production cross section, measured from a data sample collected by CMS and corresponding to an integrated luminosity of 3.1 pb−1, shows that a sizable fraction of the
\textB[`(\textB)] {\text{B}}\overline {\text{B}} pairs are produced with small opening angles. These studies provide a test of QCD and further insight into the dynamics of
\textb[`(\textb)] {\text{b}}\overline {\text{b}} production.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(3):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: A search for supersymmetry is presented using a sample of events with b jets and missing transverse momentum. The search uses
a data sample of proton-proton collisions at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of
35 pb−1, collected with the CMS detector. A total of 0.33 - 0.33 + 0.43 0.33_{ - 0.33}^{ + 0.43} (stat.) ± 0.13 (syst.) events is predicted, using control samples in the data, to arise from standard model processes, and one event is observed
in the data. Upper limits are set at the 95% confidence level on the cross sections of benchmark supersymmetric models.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2011(7):1-26. · 5.83 Impact Factor
-
CMS Collaboration,
V. Khachatryan,
A. M. Sirunyan,
A. Tumasyan,
W. Adam,
T. Bergauer,
M. Dragicevic,
J. Erö,
M. Friedl,
R. Frühwirth, [......],
C. Lazaridis,
J. Leonard,
D. Lomidze,
R. Loveless,
A. Mohapatra,
D. Reeder,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton
collisions at Ös = 0.9\sqrt{s} = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive
interactions, the average charged-hadron transverse momentum is measured to be 0.46 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between --2.4 and +2.4. At these energies, the measured pseudorapidity densities in the
central region, dN
ch/dη||η|<0.5, are 3:48 ± 0:02 (stat.) ± 0.13 (syst.) and 4:47 ± 0:04 (stat.) ± 0.16 (syst.), respectively. The results at 0.9 TeV
are in agreement with previous measurements and confirm the expectation of near equal hadron production in [`(p)] p \overline p p and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2010(2):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, [......],
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: The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36TeV were recorded by the CMS detector in December 2009.
The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their
momenta were measured in the 3.8T axial magnetic field. Results from the Tracker commissioning are presented including studies
of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the
performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well
as identification of photon conversions, nuclear interactions, and heavy-flavour decays.
European Physical Journal C 04/2012; 70(4):1165-1192. · 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, [......],
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: Results on two-particle angular correlations for charged particles emitted in proton-proton collisions at center-of-mass energies
of 0.9, 2.36, and 7 TeV are presented, using data collected with the CMS detector over a broad range of pseudorapidity (η) and azimuthal angle (ϕ). Short-range correlations in Δη, which are studied in minimum bias events, are characterized using a simple “independent cluster” parametrization in order
to quantify their strength (cluster size) and their extent in η (cluster decay width). Long-range azimuthal correlations are studied differentially as a function of charged particle multiplicity
and particle transverse momentum using a 980 nb−1 data set at 7 TeV. In high multiplicity events, a pronounced structure emerges in the two-dimensional correlation function
for particle pairs with intermediate p
T
of 1–3 GeV/c, 2.0 < |Δη| < 4.8 and Δϕ ≈ 0. This is the first observation of such a long-range, near-side feature in two-particle correlation functions in pp or p[`(p)] p\overline p collisions.
KeywordsHadron-Hadron Scattering
Journal of High Energy Physics 04/2012; 2010(9):1-38. · 5.83 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,
G. A. Pierro,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
CMS Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at
the LHC from pp collisions at a center-of-mass energy of 7 TeV, which
corresponds to an integrated luminosity of 4.8 fb-1.
Limits are set on the cross section of the standard model Higgs boson
decaying to two photons. The expected exclusion limit at 95% confidence
level is between 1.4 and 2.4 times the standard model cross section in
the mass range between 110 and 150 GeV. The analysis of the data
excludes, at 95% confidence level, the standard model Higgs boson
decaying into two photons in the mass range 128 to 132 GeV. The largest
excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local
significance of 3.1σ. The global significance of observing an
excess with a local significance ⩾3.1σ anywhere in the search
range 110-150 GeV is estimated to be 1.8σ. More data are
required to ascertain the origin of this excess.
Physics Letters B 03/2012; 710:403-425. · 3.95 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 the standard model Higgs boson (H) decaying to bb¯
when produced in association with weak vector bosons (V) is reported for
the following modes: W(μν)H, W(eν)H, Z(μμ)H, Z(ee)H and
Z(νν)H. The search is performed in a data sample corresponding to
an integrated luminosity of 4.7 fb-1, recorded by the
CMS detector in proton-proton collisions at the LHC with a
center-of-mass energy of 7 TeV. No significant excess of events above
the expectation from background is observed. Upper limits on the VH
production cross section times the H→bb¯ branching ratio, with
respect to the expectations for a standard model Higgs boson, are
derived for a Higgs boson in the mass range 110-135 GeV. In this
range, the observed 95% confidence level upper limits vary from 3.4 to
7.5 times the standard model prediction; the corresponding expected
limits vary from 2.7 to 6.7 times the standard model prediction.
Physics Letters B 03/2012; 710:284-306. · 3.95 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: Isolated photon production is measured in proton-proton and
lead-lead collisions at nucleon-nucleon centre-of-mass
energies of 2.76 TeV in the pseudorapidity range |η|<1.44 and
transverse energies ET between 20 and 80 GeV with the CMS
detector at the LHC. The measured ET spectra are found to be
in good agreement with next-to-leading-order perturbative QCD
predictions. The ratio of PbPb to pp isolated photon
ET-differential yields, scaled by the number of incoherent
nucleon-nucleon collisions, is consistent with unity for all PbPb
reaction centralities.
Physics Letters B 03/2012; 710:256-277. · 3.95 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,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson,
M Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for signatures of extra spatial dimensions in the diphoton invariant-mass spectrum has been performed with the CMS detector at the LHC. No excess of events above the standard model expectation is observed using a data sample collected in proton-proton collisions at √s=7 TeV corresponding to an integrated luminosity of 2.2 fb(-1). In the context of the large-extra-dimensions model, lower limits are set on the effective Planck scale in the range of 2.3-3.8 TeV at the 95% confidence level. These limits are the most restrictive bounds on virtual-graviton exchange to date. The most restrictive lower limits to date are also set on the mass of the first graviton excitation in the Randall-Sundrum model in the range of 0.86-1.84 TeV, for values of the associated coupling parameter between 0.01 and 0.10.
Physical Review Letters 03/2012; 108(11):111801. · 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: A search for a Higgs boson in the four-lepton decay channel H→ZZ, with each Z boson decaying to an electron or muon pair, is reported. The search covers Higgs boson mass hypotheses in the range of 110<m(H)<600 GeV. The analysis uses data corresponding to an integrated luminosity of 4.7 fb(-1) recorded by the CMS detector in pp collisions at √s=7 TeV from the LHC. Seventy-two events are observed with four-lepton invariant mass m(4ℓ)>100 GeV (with 13 below 160 GeV), while 67.1±6.0 (9.5±1.3) events are expected from background. The four-lepton mass distribution is consistent with the expectation of standard model background production of ZZ pairs. Upper limits at 95% confidence level exclude the standard model Higgs boson in the ranges of 134-158 GeV, 180-305 GeV, and 340-465 GeV. Small excesses of events are observed around masses of 119, 126, and 320 GeV, making the observed limits weaker than expected in the absence of a signal.
Physical Review Letters 03/2012; 108(11):111804. · 7.37 Impact Factor
-
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: Combined results are reported from searches for the standard model Higgs
boson in proton-proton collisions at s=7 TeV in five Higgs boson
decay modes: γγ, bb, ττ, WW, and ZZ. The explored
Higgs boson mass range is 110-600 GeV. The analysed data
correspond to an integrated luminosity of 4.6-4.8
fb-1. The expected excluded mass range in the absence
of the standard model Higgs boson is 118-543 GeV at 95% CL. The
observed results exclude the standard model Higgs boson in the mass
range 127-600 GeV at 95% CL, and in the mass range 129-525
GeV at 99% CL. An excess of events above the expected standard model
background is observed at the low end of the explored mass range making
the observed limits weaker than expected in the absence of a signal. The
largest excess, with a local significance of 3.1σ, is observed for
a Higgs boson mass hypothesis of 124 GeV. The global significance of
observing an excess with a local significance ⩾3.1σ anywhere
in the search range 110-600 (110-145) GeV is estimated to be
1.5σ(2.1σ). More data are required to ascertain the origin
of the observed excess.
Physics Letters B 02/2012; 710:26-48. · 3.95 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,
W Parker,
I Ross,
A Savin,
W H Smith,
J Swanson,
M Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for pair-produced heavy vectorlike charge-2/3 quarks, T, in pp collisions at a center-of-mass energy of 7 TeV, is performed with the CMS detector at the LHC. Events consistent with the flavor-changing-neutral-current decay of a T quark to a top quark and a Z boson are selected by requiring two leptons from the Z-boson decay, as well as an additional isolated charged lepton. In a data sample corresponding to an integrated luminosity of 1.14 fb(-1), the number of observed events is found to be consistent with the standard model background prediction. Assuming a branching fraction of 100% for the decay T→tZ, a T quark with a mass less than 475 GeV/c(2) is excluded at the 95% confidence level.
Physical Review Letters 12/2011; 107(27):271802. · 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,
W Parker,
I Ross,
A Savin,
W H Smith,
J Swanson,
M Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for events with jets and missing transverse energy is performed in a data sample of pp collisions collected at √s=7 TeV by the CMS experiment at the LHC. The analyzed data sample corresponds to an integrated luminosity of 1.14 fb(-1). In this search, a kinematic variable α(T) is used as the main discriminator between events with genuine and misreconstructed missing transverse energy. No excess of events over the standard model expectation is found. Exclusion limits in the parameter space of the constrained minimal supersymmetric extension of the standard model are set. In this model, squark masses below 1.1 TeV are excluded at 95% C.L. Gluino masses below 1.1 TeV are also ruled out at 95% C.L. for values of the universal scalar mass parameter below 500 GeV.
Physical Review Letters 11/2011; 107(22):221804. · 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,
F Palmonari,
D Reeder,
I Ross,
A Savin,
W H Smith,
J Swanson,
M Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a center-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb(-1). An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved.
Physical Review Letters 11/2011; 107(20):201804. · 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,
W Parker,
I Ross,
A Savin,
W H Smith,
J Swanson,
M Weinberg
[show abstract]
[hide abstract]
ABSTRACT: A search for the rare decays B(s)(0) → μ+ μ- and B(0) → μ+ μ- is performed in pp collisions at sqrt[s] = 7 TeV, with a data sample corresponding to an integrated luminosity of 1.14 fb(-1), collected by the CMS experiment at the LHC. In both cases, the number of events observed after all selection requirements is consistent with expectations from background and standard-model signal predictions. The resulting upper limits on the branching fractions are B(B(s)(0) → μ+ μ-) < 1.9 × 10(-8) and B(B(0) → μ+ μ-)<4.6 × 10(-9), at 95% confidence level.
Physical Review Letters 11/2011; 107(19):191802. · 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,
W. Parker,
I. Ross,
A. Savin,
W. H. Smith,
J. Swanson,
M. Weinberg
[show abstract]
[hide abstract]
ABSTRACT: The Drell-Yan differential cross section is measured in pp collisions at
sqrt {s} = 7 TeV, from a data sample collected with the CMS detector at
the LHC, corresponding to an integrated luminosity of 36
pb-1. The cross section measurement, normalized to the
measured cross section in the Z region, is reported for both the dimuon
and dielectron channels in the dilepton invariant mass range 15-600 GeV.
The normalized cross section values are quoted both in the full phase
space and within the detector acceptance. The effect of final state
radiation is also identified. The results are found to agree with
theoretical predictions.
Journal of High Energy Physics 09/2011; 10:007. · 5.83 Impact Factor
