Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of sqrt(s) = 0.9, 2.36, and 7 TeV, in five pseudorapidity ranges from |eta|<0.5 to |eta|<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 sqrt(s) = 0.9 TeV is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with 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.
Mean multiplicity for charged hadron production for |pseudorapidity| < 2.4.
Fully corrected charged hadron multiplicity spectrum for |pseudorapidity| < 0.5 at a centre-of-mass energy of 900 GeV.
Fully corrected charged hadron multiplicity spectrum for |pseudorapidity| < 1.0 at a centre-of-mass energy of 900 GeV.
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 K^0_s, Lambda, and Xi^- particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.
The rapidity production spectra per NSD event spectra for KS mesons at 0.9 and 7 TeV.
The transverse momentum production spectra per NSD event spectra for KS mesons at 0.9 and 7 TeV.
The rapidity production spectra per NSD event spectra for LAMBDA mesons at 0.9 and 7 TeV.
Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at sqrt(s) = 7 TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron yield is obtained by counting the number of reconstructed hits, hit-pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity, dN(charged)/d(eta), for |eta| < 0.5, of 5.78 +/- 0.01 (stat) +/- 0.23 (syst) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from sqrt(s) = 0.9 to 7 TeV is 66.1% +/- 1.0% (stat) +/- 4.2% (syst). The mean transverse momentum is measured to be 0.545 +/- 0.005 (stat) +/- 0.015 (syst) GeV/c. The results are compared with similar measurements at lower energies.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 0.1, 0.3, 0.5 and 0.7 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 0.9, 1.1, 1.3 and 1.5 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measured differential yield of charged hadrons as a function oftransverse momentum for pseudorapidities 1.7, 1.9, 2.1 and 2.3 for centre-of-mass energy 7000 GeV.Errors are statistical and systematic added in quadrature.
Measurements of dijet azimuthal decorrelations in pp collisions at sqrt(s) = 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 inverse picobarns. 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.
Normalized Delta_Phi distributions for events with a maximum jet pT between 80 and 110 GeV.
Normalized Delta_Phi distributions for events with a maximum jet pT between 110 and 140 GeV.
Normalized Delta_Phi distributions for events with a maximum jet pT between 140 and 200 GeV.
Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at sqrt(s) = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV (6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level.
Normalized dijet angular distribution for the dijet mass range > 2200 GeV.
Normalized dijet angular distribution for the dijet mass range 1800 to 2200 GeV.
Normalized dijet angular distribution for the dijet mass range 1400 to 1800 GeV.
Hadronic event shapes have been measured in proton-proton collisions at sqrt(s)=7 TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.
Distribution of the logarithm of the central transverse thrust for events with jet transverse momentum > 30 GeV, jet |pseudorapidity| < 1.3 and leading the jet transverse momentum from 90 to 125 GeV/c,.
Distribution of the logarithm of the central thrust minor for events with jet transverse momentum > 30 GeV, jet |pseudorapidity| < 1.3 and leading the jet transverse momentum from 90 to 125 GeV/c,.
Distribution of the logarithm of the central transverse thrust for events with jet transverse momentum > 30 GeV, jet |pseudorapidity| < 1.3 and leading the jet transverse momentum from 125 to 200 GeV/c,.
A measurement of the angular correlations between beauty and anti-beauty hadrons (B B-bar) 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 B B-bar production cross section, measured from a data sample collected by CMS and corresponding to an integrated luminosity of 3.1 inverse picobarns, shows that a sizable fraction of the B B-bar pairs are produced with small opening angles. These studies provide a test of QCD and further insight into the dynamics of b b-bar production.
Cross section as a function of DELTA(R) for leading jet transverse momentum > 56 GeV. . The (sys) error in the table is due to the limited MC statistics and is uncorrelated bin-to-bin. The other two systematic errors are correlated.
Cross section as a function of DELTA(R) for leading jet transverse momentum > 84 GeV. . The (sys) error in the table is due to the limited MC statistics and is uncorrelated bin-to-bin. The other two systematic errors are correlated.
Cross section as a function of DELTA(R) for leading jet transverse momentum > 120 GeV. . The (sys) error in the table is due to the limited MC statistics and is uncorrelated bin-to-bin. The other two systematic errors are correlated. Note that these two systematic errors are different for the final point.
A measurement of the b-hadron production cross section in proton-proton collisions at sqrt(s)=7 TeV is presented. The dataset, corresponding to 85 inverse nanobarns, 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 greater than 6 GeV with respect to the beam direction and pseudorapidity less than 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 sigma(pp to b+X to mu + X') =1.32 +/- 0.01 (stat) +/- 0.30 (syst) +/- 0.15 (lumi) microbarns.
Total inclusive cross section in the visible kinematic range.
Muon transverse momentum differential distibution.
Muon pseudorapidity differential distibution.
From a total data sample of 701.1 pb^-1 recorded with e+e- centre-of-mass energies of sqrt = 161-209 GeV with the OPAL detector at LEP, 11693 W-pair candidate events are selected. These data are used to obtain measurements of the W-pair production cross sections at 10 different centre-of-mass energies. The ratio of the measured cross sections to the Standard Model expectation is found to be: data/SM = 1.002 +- 0.011(stat.) +- 0.007(syst.) +- 0.005(theory), where the uncertainties are statistical, experimental systematics and theory systematics respectively. The data are used to determine the W boson branching fractions, which are found to be consistent with lepton universality of the charged current interaction. Assuming lepton universality, the branching ratio to hadrons is determined to be 67.41 +- 0.37(stat.) +- 0.23(syst.)%, from which the CKM matrix element Vcs is determined to be 0.96+-0.017(stat.)+-0.012(syst.). The differential cross section as a function of the W^- production angle is measured for the qqev and qqmv final states. The results described in this paper are consistent with the expectations from the Standard Model.
Measured cross section for the (lepton nu lepton nu) decay mode.
Measured cross section for the (quark quark lepton nu) decay mode.
Measured cross section for the (quark quark quark quark) decay mode.
The inclusive production of charged hadrons in the collisions of quasi-real photons e+e- -> e+e- +X has been measured using the OPAL detector at LEP. The data were taken at e+e- centre-of-mass energies from 183 to 209 GeV. The differential cross-sections as a function of the transverse momentum and the pseudorapidity of the hadrons are compared to theoretical calculations of up to next-to-leading order (NLO) in the strong coupling constant alpha{s}. The data are also compared to a measurement by the L3 Collaboration, in which a large deviation from the NLO predictions is observed.
Differential inclusive charged hadron production cross section as a function of PT.
Differential inclusive charged hadron production cross section as a function of PT.
Differential inclusive charged hadron production cross section as a function of PT.
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