The prompt D^{0} meson azimuthal anisotropy coefficients, v_{2} and v_{3}, are measured at midrap... more The prompt D^{0} meson azimuthal anisotropy coefficients, v_{2} and v_{3}, are measured at midrapidity (|y|<1.0) in Pb-Pb collisions at a center-of-mass energy sqrt[s_{NN}]=5.02 TeV per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum (p_{T}) range of 1 to 40 GeV/c, for central and midcentral collisions. The v_{2} coefficient is found to be positive throughout the p_{T} range studied. The first measurement of the prompt D^{0} meson v_{3} coefficient is performed, and values up to 0.07 are observed for p_{T} around 4 GeV/c. Compared to measurements of charged particles, a similar p_{T} dependence, but smaller magnitude for p_{T}<6 GeV/c, is found for prompt D^{0} meson v_{2} and v_{3} coefficients. The results are consistent with the presence of collective motion of charm quarks at low p_{T} and a path length dependence of charm quark energy loss at high p_{T}, thereby providing new constraints on the theoretica...
The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV and... more The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, ϒ(2S) and ϒ(3S), to the ground state, ϒ(1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [ϒ(nS)/ϒ(1S)]_{Pb-Pb}/[ϒ(nS)/ϒ(1S)]_{pp}, are measured to be 0.308±0.055(stat)±0.019(syst) for the ϒ(2S) and less than 0.26 at 95% confidence level for the ϒ(3S). No significant ϒ(3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as ϒ transverse momentum and rapidity. No significant dependencies are observed.
The European physical journal. C, Particles and fields
Measurements of the [Formula: see text][Formula: see text] production cross sections in proton-pr... more Measurements of the [Formula: see text][Formula: see text] production cross sections in proton-proton collisions at center-of-mass energies of 7 and 8[Formula: see text] are presented. Candidate events for the leptonic decay mode [Formula: see text], where [Formula: see text] denotes an electron or a muon, are reconstructed and selected from data corresponding to an integrated luminosity of 5.1 (19.6)[Formula: see text] at 7 (8)[Formula: see text] collected with the CMS experiment. The measured cross sections, [Formula: see text] at 7[Formula: see text], and [Formula: see text] at 8[Formula: see text], are in good agreement with the standard model predictions with next-to-leading-order accuracy. The selected data are analyzed to search for anomalous triple gauge couplings involving the [Formula: see text][Formula: see text] final state. In the absence of any deviation from the standard model predictions, limits are set on the relevant parameters. These limits are then combined with ...
Results are presented from a search for a W boson using a dataset corresponding to 5.0 fb −1 of i... more Results are presented from a search for a W boson using a dataset corresponding to 5.0 fb −1 of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at √ s = 7 TeV. The W boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both lefthanded and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W → tb, leading to a final state signature with a single electron or muon, missing transverse energy, and jets, at least one of which is identified as a b-jet. A W boson that couples to the right-handed (left-handed) chiral projections of the fermions with the same coupling constants as the W is excluded for masses below 1.85 (1.51) TeV at the 95% confidence level. For the first time using LHC data, constraints on the W gauge couplings for a set of left-and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.
A measurement of the t t production cross section in proton-proton collisions at a centre-of-mass... more A measurement of the t t production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 pb -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 signal from W+jets and QCD multijet background events. The measured cross section is 173 +39 -32 (stat. + syst.) pb, consistent with standard model expectations.
The production of jets associated to bottom quarks is measured for the first time in PbPb collisi... more The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (p(T)) range of 80-250 GeV/c, and within pseudorapidity…
A search for narrow resonances at high mass in the dimuon and dielectron channels has been perfor... more 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 √ 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 (G KK) in the Randall-Sundrum model. Upper limits on the inclusive cross section of Z (G KK) → + − relative to Z → + − are presented. These limits exclude at 95% confidence level a Z with standard-modellike couplings below 1140 GeV, the superstring-inspired Z ψ below 887 GeV, and, for values of the coupling parameter k/M Pl of 0.05 (0.1), Kaluza-Klein gravitons below 855 (1079) GeV.
A search for the standard model Higgs boson in the H → ZZ → 2ℓ2ν decay channel, where ℓ = e or μ,... more A search for the standard model Higgs boson in the H → ZZ → 2ℓ2ν decay channel, where ℓ = e or μ, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 fb−1. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.
Yields of prompt and non-prompt J/ψ, as well as $ \Upsilon $ (1S) mesons, are measured by the CMS... more Yields of prompt and non-prompt J/ψ, as well as $ \Upsilon $ (1S) mesons, are measured by the CMS experiment via their μ + μ − decays in PbPb and pp collisions at $ \sqrt {{{s_{\text{NN}}}}} = 2.76 $ TeV for quarkonium rapidity |y| < 2.4. Differential cross sections and nuclear modification factors are reported as functions of y and transverse momentum p T, as well as collision centrality. For prompt J/ψ with relatively high p T (6.5 < p T < 30 GeV/c), a strong, centrality-dependent suppression is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. In the same kinematic range, a suppression of non-prompt J/ψ, which is sensitive to the in-medium b-quark energy loss, is measured for the first time. Also the low-p T $ \Upsilon $ (1S) mesons are suppressed in PbPb collisions.
A search for the standard model Higgs boson decaying into two Z bosons with subsequent decay into... more A search for the standard model Higgs boson decaying into two Z bosons with subsequent decay into a final state containing two quark jets and two leptons, H → ZZ(*) → q $ \overline {\text{q}} $ ℓ − ℓ + is presented. Results are based on data corresponding to an integrated luminosity of 4.6 fb−1 of proton-proton collisions at $ \sqrt {s} = 7 $ TeV, collected with the CMS detector at the LHC. In order to discriminate between signal and background events, kinematic and topological quantities, including the angular spin correlations of the decay products, are employed. Events are further classified according to the probability of the jets to originate from quarks of light or heavy flavor or from gluons. No evidence for the Higgs boson is found, and upper limits on its production cross section are determined for a Higgs boson of mass between 130 and 600 GeV.
Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at... more Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at √ s NN = 2.76 TeV The CMS collaboration
A new heavy gauge boson, W , decaying to a muon and a neutrino, is searched for in pp collisions ... more A new heavy gauge boson, W , decaying to a muon and a neutrino, is searched for in pp collisions at a centre-of-mass of 7 TeV. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 36 pb −1. No significant excess of events above the standard model expectation is found in the transverse mass distribution of the muon-neutrino system. Masses below 1.40 TeV are excluded at the 95% confidence level for a sequential standard-model-like W. The W mass lower limit increases to 1.58 TeV when the present analysis is combined with the CMS result for the electron channel.
with typographical errors in an author name in Refs. [4] and [9]. Reference [4] should read as ''... more with typographical errors in an author name in Refs. [4] and [9]. Reference [4] should read as ''U. Baur, I. Hinchliffe.. .'' and Ref. [9] should read as ''E. Eichten, I Hinchliffe,.. ..'' The references have been corrected as of 6 January 2011. The references are incorrect in the printed version of the journal.
A study of events with missing transverse energy and an energetic jet is performed using pp colli... more A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a centre-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.
A search for the pair production of a heavy, narrow resonance decaying into two jets has been per... more A search for the pair production of a heavy, narrow resonance decaying into two jets has been performed using events collected in ffiffi ffi s p ¼ 7 TeV pp collisions with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5:0 fb À1. Events are selected with at least four jets and two dijet combinations with similar dijet mass. No resonances are found in the dijet mass spectrum. The upper limit at 95% confidence level on the product of the resonance pair production cross section, the branching fractions into dijets, and the acceptance varies from 0.22 to 0.005 pb, for resonance masses between 250 and 1200 GeV. Pair-produced colorons decaying into q " q are excluded for coloron masses between 250 and 740 GeV.
Measurements of dijet azimuthal decorrelations in pp collisions at ffiffi ffi s p ¼ 7 TeV using t... more Measurements of dijet azimuthal decorrelations in pp collisions at ffiffi ffi s p ¼ 7 TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2:9 pb À1. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.
A search for pair production of second-generation scalar leptoquarks in the final state with two ... more A search for pair production of second-generation scalar leptoquarks in the final state with two muons and two jets is performed using proton-proton collision data at √ s = 7 TeV collected by the CMS detector at the LHC. The data sample used corresponds to an integrated luminosity of 34 pb −1. The number of observed events is in good agreement with the predictions from the standard model processes. An upper limit is set on the second-generation leptoquark cross section times β 2 as a function of the leptoquark mass, and leptoquarks with masses below 394 GeV are excluded at a 95% confidence level for β = 1, where β is the leptoquark branching fraction into a muon and a quark. These limits are the most stringent to date.
The prompt D^{0} meson azimuthal anisotropy coefficients, v_{2} and v_{3}, are measured at midrap... more The prompt D^{0} meson azimuthal anisotropy coefficients, v_{2} and v_{3}, are measured at midrapidity (|y|<1.0) in Pb-Pb collisions at a center-of-mass energy sqrt[s_{NN}]=5.02 TeV per nucleon pair with data collected by the CMS experiment. The measurement is performed in the transverse momentum (p_{T}) range of 1 to 40 GeV/c, for central and midcentral collisions. The v_{2} coefficient is found to be positive throughout the p_{T} range studied. The first measurement of the prompt D^{0} meson v_{3} coefficient is performed, and values up to 0.07 are observed for p_{T} around 4 GeV/c. Compared to measurements of charged particles, a similar p_{T} dependence, but smaller magnitude for p_{T}<6 GeV/c, is found for prompt D^{0} meson v_{2} and v_{3} coefficients. The results are consistent with the presence of collective motion of charm quarks at low p_{T} and a path length dependence of charm quark energy loss at high p_{T}, thereby providing new constraints on the theoretica...
The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV and... more The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, ϒ(2S) and ϒ(3S), to the ground state, ϒ(1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [ϒ(nS)/ϒ(1S)]_{Pb-Pb}/[ϒ(nS)/ϒ(1S)]_{pp}, are measured to be 0.308±0.055(stat)±0.019(syst) for the ϒ(2S) and less than 0.26 at 95% confidence level for the ϒ(3S). No significant ϒ(3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as ϒ transverse momentum and rapidity. No significant dependencies are observed.
The European physical journal. C, Particles and fields
Measurements of the [Formula: see text][Formula: see text] production cross sections in proton-pr... more Measurements of the [Formula: see text][Formula: see text] production cross sections in proton-proton collisions at center-of-mass energies of 7 and 8[Formula: see text] are presented. Candidate events for the leptonic decay mode [Formula: see text], where [Formula: see text] denotes an electron or a muon, are reconstructed and selected from data corresponding to an integrated luminosity of 5.1 (19.6)[Formula: see text] at 7 (8)[Formula: see text] collected with the CMS experiment. The measured cross sections, [Formula: see text] at 7[Formula: see text], and [Formula: see text] at 8[Formula: see text], are in good agreement with the standard model predictions with next-to-leading-order accuracy. The selected data are analyzed to search for anomalous triple gauge couplings involving the [Formula: see text][Formula: see text] final state. In the absence of any deviation from the standard model predictions, limits are set on the relevant parameters. These limits are then combined with ...
Results are presented from a search for a W boson using a dataset corresponding to 5.0 fb −1 of i... more Results are presented from a search for a W boson using a dataset corresponding to 5.0 fb −1 of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at √ s = 7 TeV. The W boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both lefthanded and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W → tb, leading to a final state signature with a single electron or muon, missing transverse energy, and jets, at least one of which is identified as a b-jet. A W boson that couples to the right-handed (left-handed) chiral projections of the fermions with the same coupling constants as the W is excluded for masses below 1.85 (1.51) TeV at the 95% confidence level. For the first time using LHC data, constraints on the W gauge couplings for a set of left-and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.
A measurement of the t t production cross section in proton-proton collisions at a centre-of-mass... more A measurement of the t t production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 pb -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 signal from W+jets and QCD multijet background events. The measured cross section is 173 +39 -32 (stat. + syst.) pb, consistent with standard model expectations.
The production of jets associated to bottom quarks is measured for the first time in PbPb collisi... more The production of jets associated to bottom quarks is measured for the first time in PbPb collisions at a center-of-mass energy of 2.76 TeV per nucleon pair. Jet spectra are reported in the transverse momentum (p(T)) range of 80-250 GeV/c, and within pseudorapidity…
A search for narrow resonances at high mass in the dimuon and dielectron channels has been perfor... more 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 √ 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 (G KK) in the Randall-Sundrum model. Upper limits on the inclusive cross section of Z (G KK) → + − relative to Z → + − are presented. These limits exclude at 95% confidence level a Z with standard-modellike couplings below 1140 GeV, the superstring-inspired Z ψ below 887 GeV, and, for values of the coupling parameter k/M Pl of 0.05 (0.1), Kaluza-Klein gravitons below 855 (1079) GeV.
A search for the standard model Higgs boson in the H → ZZ → 2ℓ2ν decay channel, where ℓ = e or μ,... more A search for the standard model Higgs boson in the H → ZZ → 2ℓ2ν decay channel, where ℓ = e or μ, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 fb−1. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.
Yields of prompt and non-prompt J/ψ, as well as $ \Upsilon $ (1S) mesons, are measured by the CMS... more Yields of prompt and non-prompt J/ψ, as well as $ \Upsilon $ (1S) mesons, are measured by the CMS experiment via their μ + μ − decays in PbPb and pp collisions at $ \sqrt {{{s_{\text{NN}}}}} = 2.76 $ TeV for quarkonium rapidity |y| < 2.4. Differential cross sections and nuclear modification factors are reported as functions of y and transverse momentum p T, as well as collision centrality. For prompt J/ψ with relatively high p T (6.5 < p T < 30 GeV/c), a strong, centrality-dependent suppression is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. In the same kinematic range, a suppression of non-prompt J/ψ, which is sensitive to the in-medium b-quark energy loss, is measured for the first time. Also the low-p T $ \Upsilon $ (1S) mesons are suppressed in PbPb collisions.
A search for the standard model Higgs boson decaying into two Z bosons with subsequent decay into... more A search for the standard model Higgs boson decaying into two Z bosons with subsequent decay into a final state containing two quark jets and two leptons, H → ZZ(*) → q $ \overline {\text{q}} $ ℓ − ℓ + is presented. Results are based on data corresponding to an integrated luminosity of 4.6 fb−1 of proton-proton collisions at $ \sqrt {s} = 7 $ TeV, collected with the CMS detector at the LHC. In order to discriminate between signal and background events, kinematic and topological quantities, including the angular spin correlations of the decay products, are employed. Events are further classified according to the probability of the jets to originate from quarks of light or heavy flavor or from gluons. No evidence for the Higgs boson is found, and upper limits on its production cross section are determined for a Higgs boson of mass between 130 and 600 GeV.
Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at... more Dependence on pseudorapidity and on centrality of charged hadron production in PbPb collisions at √ s NN = 2.76 TeV The CMS collaboration
A new heavy gauge boson, W , decaying to a muon and a neutrino, is searched for in pp collisions ... more A new heavy gauge boson, W , decaying to a muon and a neutrino, is searched for in pp collisions at a centre-of-mass of 7 TeV. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 36 pb −1. No significant excess of events above the standard model expectation is found in the transverse mass distribution of the muon-neutrino system. Masses below 1.40 TeV are excluded at the 95% confidence level for a sequential standard-model-like W. The W mass lower limit increases to 1.58 TeV when the present analysis is combined with the CMS result for the electron channel.
with typographical errors in an author name in Refs. [4] and [9]. Reference [4] should read as ''... more with typographical errors in an author name in Refs. [4] and [9]. Reference [4] should read as ''U. Baur, I. Hinchliffe.. .'' and Ref. [9] should read as ''E. Eichten, I Hinchliffe,.. ..'' The references have been corrected as of 6 January 2011. The references are incorrect in the printed version of the journal.
A study of events with missing transverse energy and an energetic jet is performed using pp colli... more A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a centre-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.
A search for the pair production of a heavy, narrow resonance decaying into two jets has been per... more A search for the pair production of a heavy, narrow resonance decaying into two jets has been performed using events collected in ffiffi ffi s p ¼ 7 TeV pp collisions with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 5:0 fb À1. Events are selected with at least four jets and two dijet combinations with similar dijet mass. No resonances are found in the dijet mass spectrum. The upper limit at 95% confidence level on the product of the resonance pair production cross section, the branching fractions into dijets, and the acceptance varies from 0.22 to 0.005 pb, for resonance masses between 250 and 1200 GeV. Pair-produced colorons decaying into q " q are excluded for coloron masses between 250 and 740 GeV.
Measurements of dijet azimuthal decorrelations in pp collisions at ffiffi ffi s p ¼ 7 TeV using t... more Measurements of dijet azimuthal decorrelations in pp collisions at ffiffi ffi s p ¼ 7 TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2:9 pb À1. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.
A search for pair production of second-generation scalar leptoquarks in the final state with two ... more A search for pair production of second-generation scalar leptoquarks in the final state with two muons and two jets is performed using proton-proton collision data at √ s = 7 TeV collected by the CMS detector at the LHC. The data sample used corresponds to an integrated luminosity of 34 pb −1. The number of observed events is in good agreement with the predictions from the standard model processes. An upper limit is set on the second-generation leptoquark cross section times β 2 as a function of the leptoquark mass, and leptoquarks with masses below 394 GeV are excluded at a 95% confidence level for β = 1, where β is the leptoquark branching fraction into a muon and a quark. These limits are the most stringent to date.
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