-
The Collaboration,
F. D. Aaron,
C. Alexa,
V. Andreev,
S. Backovic,
A. Baghdasaryan,
S. Baghdasaryan,
E. Barrelet,
W. Bartel,
K. Begzsuren, [......],
Y. Vazdik,
M. von den Driesch,
D. Wegener,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
H. Zohrabyan,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: A search for squarks in R-parity violating supersymmetry is performed in e
±
p collisions at HERA using the H1 detector. The full data sample taken at a centre-of-mass energy Ös=319\sqrt{s}=319GeV is used for the analysis, corresponding to an integrated luminosity of 255pb−1 of e
+
p and 183pb−1 of e
−
p collision data. The resonant production of squarks via a Yukawa coupling λ′ is considered, taking into account direct and indirect R-parity violating decay modes. Final states with jets and leptons are investigated. No evidence for squark production is found
and mass dependent limits on λ′ are obtained in the framework of the Minimal Supersymmetric Standard Model and in the Minimal Supergravity Model. In the
considered part of the parameter space, for a Yukawa coupling of electromagnetic strength λ′=0.3, squarks of all flavours are excluded up to masses of 275GeV at 95% confidence level, with down-type squarks further
excluded up to masses of 290GeV.
European Physical Journal C 04/2012; 71(3):1-16. · 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 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
-
A. Aktas,
V. Andreev,
T. Anthonis,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
A. Babaev,
S. Backovic,
A. Baghdasaryan, [......],
J. Zálešák,
Z. Zhang,
A. Zhelezov,
A. Zhokin,
Y.C. Zhu,
J. Zimmermann,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Inclusive D*± production is measured in deep-inelastic ep scattering at HERA with the H1 detector. In addition, the production of dijets
in events with a D*± meson is investigated. The analysis covers values of photon virtuality 2 ≤ Q2 ≤ 100GeV2 and of inelasticity 0.05≤y≤0.7. Differential cross sections are measured as a function of Q2 and x and of various D*± meson and jet observables. Within the experimental and theoretical uncertainties all measured cross sections are found to
be adequately described by next-to-leading order (NLO) QCD calculations, based on the photon–gluon fusion process and DGLAP
evolution, without the need for an additional resolved component of the photon beyond what is included at NLO. A reasonable
description of the data is also achieved by a prediction based on the CCFM evolution of partons involving the kT-unintegrated gluon distribution of the proton.
European Physical Journal C 04/2012; 51(2):271-287. · 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 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 Collaboration,
F. D. Aaron,
C. Alexa,
V. Andreev,
S. Backovic,
A. Baghdasaryan,
S. Baghdasaryan,
E. Barrelet,
W. Bartel,
O. Behrend, [......],
Y. Vazdik,
M. von den Driesch,
D. Wegener,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
H. Zohrabyan,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: A measurement is presented of the inclusive neutral current e
±
p scattering cross section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam
energies E
p
of 920, 575, and 460GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5GeV2<Q
2<120GeV2, small values of Bjorken x, 2.9⋅10−5<x<0.01, and extends to high inelasticity up to y=0.85. The structure function F
L
is measured by combining the new results with previously published H1 data at E
p
=920GeV and E
p
=820GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q
2 and low x kinematic domain.
European Physical Journal C 04/2012; 71(3):1-50. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
C. Alexa,
V. Andreev,
B. Antunovic,
S. Backovic,
A. Baghdasaryan,
E. Barrelet,
W. Bartel,
K. Begzsuren, [......],
D. Wegener,
C. Wissing,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
T. Zimmermann,
H. Zohrabyan,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: The production of leading neutrons, where the neutron carries a large fraction x
L
of the incoming proton’s longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The data
were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122pb−1. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6<Q
2<100GeV2, Bjorken scaling variable 1.5⋅10−4<x<3⋅10−2, longitudinal momentum fraction 0.32<x
L
<0.95 and neutron transverse momentum p
T
<0.2GeV. The leading neutron structure function, F2LN(3)(Q2,x,xL)F_{2}^{LN(3)}(Q^{2},x,x_{L}), and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of Q
2, x and x
L
. Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape
of the pion structure function.
European Physical Journal C 04/2012; 68(3):381-399. · 3.63 Impact Factor
-
F.D. Aaron,
A. Aktas,
C. Alexa,
V. Andreev,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
S. Backovic,
A. Baghdasaryan, [......],
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhelezov,
A. Zhokin,
Y.C. Zhu,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: Three- and four-jet production is measured in deep-inelastic ep scattering at low x and Q2 with the H1 detector using an integrated luminosity of 44.2pb-1. Several phase space regions are selected for the three-jet analysis in order to study the underlying parton dynamics from
global topologies to the more restrictive regions of forward jets close to the proton direction. The measurements of cross
sections for events with at least three jets are compared to fixed order QCD predictions of
O(a\texts2){\mathcal{O}}(\alpha_{{\text{s}}}^2) and
O(a\texts3){\mathcal{O}}(\alpha_{{\text{s}}}^3) and with Monte Carlo simulation programs where higher order effects are approximated by parton showers. A good overall description
is provided by the
O(a\texts3){\mathcal{O}}(\alpha_{{\text{s}}}^3) calculation. Too few events are predicted at the lowest x∼10-4, especially for topologies with two forward jets. This hints to large contributions at low x from initial state radiation
of gluons close to the proton direction and unordered in transverse momentum. The Monte Carlo program in which gluon radiation
is generated by the colour dipole model gives a good description of both the three- and the four-jet data in absolute normalisation
and shape.
European Physical Journal C 04/2012; 54(3):389-409. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
C. Alexa,
V. Andreev,
S. Backovic,
A. Baghdasaryan,
E. Barrelet,
W. Bartel,
K. Begzsuren,
A. Belousov, [......],
Y. Vazdik,
M. von den Driesch,
D. Wegener,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
H. Zohrabyan,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: Measurements of cross sections for events with charm and beauty jets in deep inelastic scattering at HERA are presented. Events
with jets of transverse energy $E_{T}^{\mathrm{jet}}>6$E_{T}^{\mathrm{jet}}>6GeV and pseudorapidity −1.0<η
jet<1.5 in the laboratory frame are selected in the kinematic region of photon virtuality Q
2>6GeV2 and inelasticity variable 0.07<y<0.625. Measurements are also made requiring a jet in the Breit frame with $E_{T}^{*{\mathrm{jet}}}>6$E_{T}^{*{\mathrm{jet}}}>6GeV. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of
189pb−1. The numbers of charm and beauty jets are determined using variables reconstructed using the H1 vertex detector with which
the impact parameters of the tracks to the primary vertex and the position of secondary vertices are measured. The measurements
are compared with QCD predictions and with previous measurements where heavy flavours are identified using muons.
European Physical Journal C 04/2012; 71(1):1-21. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
C. Alexa,
K. Alimujiang,
V. Andreev,
B. Antunovic,
A. Asmone,
S. Backovic,
A. Baghdasaryan,
E. Barrelet, [......],
Ch. Wissing,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
R. Zus
[show abstract]
[hide abstract]
ABSTRACT: The production of jets is studied in deep-inelastic e
±
p scattering at large negative four momentum transfer squared 150<Q
2<15000GeV2 using HERA data taken in 1999–2007, corresponding to an integrated luminosity of 395pb−1. Inclusive jet, 2-jet and 3-jet cross sections, normalised to the neutral current deep-inelastic scattering cross sections,
are measured as functions of Q
2, jet transverse momentum and proton momentum fraction. The measurements are well described by perturbative QCD calculations
at next-to-leading order corrected for hadronisation effects. The strong coupling as determined from these measurements is
as(MZ)=0.1168±0.0007(exp.)+0.0046-0.0030(th.)±0.0016\alpha_{s}(M_{Z})=0.1168\pm0.0007\,\mathrm{(exp.)}{}^{+0.0046}_{-0.0030}\,\mathrm{(th.)}\pm 0.0016
(PDF).
European Physical Journal C 04/2012; 65(3):363-383. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
M. Aldaya Martin,
C. Alexa,
V. Andreev,
B. Antunovic,
A. Asmone,
S. Backovic,
A. Baghdasaryan,
E. Barrelet, [......],
Ch. Wissing,
E. Wünsch,
J. Žáček,
J. Záleák,
Z. Zhang,
A. Zhokin,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
R. Zus
[show abstract]
[hide abstract]
ABSTRACT: Diffractive electroproduction of ρ and ϕ mesons is measured at HERA with the H1 detector in the elastic and proton dissociative
channels. The data correspond to an integrated luminosity of 51 pb−1. About 10500 ρ and 2000 φ events are analysed in the kinematic range of squared photon virtuality 2.5 ≤ Q
2 ≤ 60 GeV2, photon-proton centre of mass energy 35 ≤ W ≤ 180 GeV and squared four-momentum transfer to the proton |t| ≤ 3 GeV2. The total, longitudinal and transverse cross sections are measured as a function of Q
2, W and |t|. The measurements show a transition to a dominantly “hard” behaviour, typical of high gluon densities and small q[`(q)] q\overline q dipoles, for Q
2 larger than 10 to 20 GeV2. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (Q
2+M
2
V
)/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables.
The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases
are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction
in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal
dipole cross sections.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(5):1-111. · 5.83 Impact Factor
-
Collaboration,
F. D. Aaron,
C. Alexa,
V. Andreev,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
A. Bacchetta,
S. Backovic, [......],
V. Yeganov,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhelezov,
A. Zhokin,
Y. C. Zhu,
T. Zimmermann,
H. Zohrabyan,
F. Zomer
[show abstract]
[hide abstract]
ABSTRACT: The production of neutral strange hadrons is investigated using deep-inelastic scattering events measured with the H1 detector
at HERA. The measurements are made in the phase space defined by the negative four-momentum transfer squared of the photon
2<Q
2<100 GeV2 and the inelasticity 0.1<y<0.6. The K
s
0 and
\varLambda([`\varLambda])\varLambda(\bar{\varLambda})
production cross sections and their ratios are determined. K
s
0 production is compared to the production of charged particles in the same region of phase space. The Λ–
[`\varLambda]\bar{\varLambda}
asymmetry is also measured and found to be consistent with zero. Predictions of leading order Monte Carlo programs are compared
to the data.
European Physical Journal C 04/2012; 61(2):185-205. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
M. Aldaya Martin,
C. Alexa,
V. Andreev,
B. Antunovic,
S. Backovic,
A. Baghdasaryan,
E. Barrelet,
W. Bartel, [......],
Ch. Wissing,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
R. Zus
[show abstract]
[hide abstract]
ABSTRACT: The production of prompt photons is measured in the photoproduction regime of electron–proton scattering at HERA. The analysis
is based on a data sample corresponding to a total integrated luminosity of 340pb−1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the
range
6 < ETg < 156
European Physical Journal C 04/2012; 66(1):17-33. · 3.63 Impact Factor
-
The Collaboration,
F. D. Aaron,
M. Aldaya Martin,
C. Alexa,
K. Alimujiang,
V. Andreev,
B. Antunovic,
A. Asmone,
S. Backovic,
A. Baghdasaryan, [......],
C. Wissing,
E. Wünsch,
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhokin,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
R. Zus
[show abstract]
[hide abstract]
ABSTRACT: Inclusive charm and beauty cross sections are measured in e
−
p and e
+
p neutral current collisions at HERA in the kinematic region of photon virtuality 5≤Q
2≤2000GeV2 and Bjorken scaling variable 0.0002≤x≤0.05. The data were collected with the H1 detector in the years 2006 and 2007 corresponding to an integrated luminosity of
189pb−1. The numbers of charm and beauty events are determined using variables reconstructed by the H1 vertex detector including
the impact parameter of tracks to the primary vertex and the position of the secondary vertex. The measurements are combined
with previous data and compared to QCD predictions.
European Physical Journal C 04/2012; 65(1):89-109. · 3.63 Impact Factor
-
A. Aktas,
C. Alexa,
V. Andreev,
T. Anthonis,
B. Antunovic,
S. Aplin,
A. Asmone,
A. Astvatsatourov,
S. Backovic,
A. Baghdasaryan, [......],
J. Žáček,
J. Zálešák,
Z. Zhang,
A. Zhelezov,
A. Zhokin,
Y.C. Zhu,
T. Zimmermann,
H. Zohrabyan,
F. Zomer,
The Collaboration
[show abstract]
[hide abstract]
ABSTRACT: A search for narrow baryonic resonances decaying into Ξ-π- or Ξ-π+ and their antiparticles is carried out with the H1 detector using deep inelastic scattering events at HERA in the range of
negative photon four-momentum transfer squared 2 < Q2 < 100GeV2. No signal is observed for a new baryonic state in the mass range 1600–2300MeV in either the doubly charged or the neutral
decay channels. The known Ξ(1530)0 is observed through its decay mode into Ξ-π+. Upper limits are given on the ratio of the production rates of new baryonic states, such as the hypothetical pentaquark
states Ξ–
5q or Ξ0
5q, relative to the Ξ(1530)0 baryon state.
European Physical Journal C 04/2012; 52(3):507-514. · 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: 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
-
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
-
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
-
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
-
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
