Measurements of the ZZ production cross sections in proton-proton collisions at center-of-mass energies of 7 and 8 TeV are presented. Candidate events for the leptonic decay mode ZZ to 2 l 2 nu, where l denotes an electron or a muon, are reconstructed and selected from data corresponding to an integrated luminosity of 5.1 (19.6) inverse femtobarns at 7 (8) TeV collected with the CMS experiment. The measured cross sections, sigma(pp to ZZ) = 5.1 -1.4 +1.5 (stat) -1.1 +1.4 (syst) +/- 0.1 (lumi) pb at 7 TeV, and 7.2 -0.8 +0.8 (stat.) -1.5 +1.9 (syst) +/- 0.2 (lumi) pb at 8 TeV, 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 ZZ 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 the previously published CMS results for ZZ in 4 l final states, yielding the most stringent constraints on the anomalous couplings.
Using a maximum-likelihood fit to the reduced-MET data distributions, with all the systematic uncertainties incorporated as nuisance parameters, we obtain the following cross sections for the pp->ZZ process (with both Z bosons in the mass range 60-120 GeV). The first systematic uncertainty is the combined systematic uncertainty excluding luminosity, the second is the luminosity. The theory calculations are 6.2+0.3-0.2 pb at 7 TeV and 7.6+0.4-0.3 pb at 8 TeV, including NLO QCD and NLO EW corrections.
A measurement of the Z gamma to nu nu-bar gamma production cross section in pp collisions at sqrt(s) = 8 TeV is presented, using data corresponding to an integrated luminosity of 19.6 inverse femtobarns collected with the CMS detector at the LHC. This measurement is based on the observation of events with large missing energy and with a single photon with transverse momentum above 145 GeV and absolute pseudorapidity in the range |eta| < 1.44. The measured Z gamma to nu nu-bar gamma production cross section, 52.7 +/- 2.1(stat) +/- 6.4 (syst) +/- 1.4 (lumi) fb, agrees well with the standard model prediction of 50.0 +2.4 -2.2 fb. A study of the photon transverse momentum spectrum yields the most stringent limits to date on the anomalous Z-Z-gamma and Z-gamma-gamma trilinear gauge boson couplings.
Z gamma -> nu nu gamma production cross section.
One-dimensional 95% CL limits on ZVgamma anomalous trilinear gauge couplings from the Z gamma -> nu nu gamma channel.
The production of J/psi mesons is studied in pp collisions at sqrt(s)=7 TeV with the CMS experiment at the LHC. The measurement is based on a dimuon sample corresponding to an integrated luminosity of 314 inverse nanobarns. The J/psi differential cross section is determined, as a function of the J/psi transverse momentum, in three rapidity ranges. A fit to the decay length distribution is used to separate the prompt from the non-prompt (b hadron to J/psi) component. Integrated over J/psi transverse momentum from 6.5 to 30 GeV/c and over rapidity in the range |y| < 2.4, the measured cross sections, times the dimuon decay branching fraction, are 70.9 \pm 2.1 (stat.) \pm 3.0 (syst.) \pm 7.8(luminosity) nb for prompt J/psi mesons assuming unpolarized production and 26.0 \pm 1.4 (stat.) \pm 1.6 (syst.) \pm 2.9 (luminosity) nb for J/psi mesons from b-hadron decays.
Total cross section within the kinematic limits for prompt and non-prompt J/PSI production times branching ratio into MU+ MU-, assuming zero polarizartion. The second systematic error is the luminosity uncertainty.
Differential inclusive cross J/PSI section for the |rapidity| range 0 to 1.2 for each prompt J/PSI polarization scenario considered.
Differential inclusive cross J/PSI section for the |rapidity| range 1.2 to 1.6 for each prompt J/PSI polarization scenario considered.
The cross section for Higgs boson production in pp collisions is studied using the H to WW decay mode, followed by leptonic decays of the W bosons to an oppositely charged electron-muon pair in the final state. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.4 inverse femtobarns. The Higgs boson transverse momentum (pT) is reconstructed using the lepton pair pT and missing pT. The differential cross section times branching fraction is measured as a function of the Higgs boson pT in a fiducial phase space defined to match the experimental acceptance in terms of the lepton kinematics and event topology. The production cross section times branching fraction in the fiducial phase space is measured to be 39 +/- 8 (stat) +/- 9 (syst) fb. The measurements are found to agree, within experimental uncertainties, with theoretical calculations based on the standard model.
The fiducial differential cross section in each Higgs pT bin. The first uncertainty is the total (stat+syst) uncertainty. The second is the statistical uncertainty and the third and fourth are Type A and Type B systematic uncertainties, respectively. The last one is the model dependence uncertainty (Type C).
The measured total cross section in the fiducial region. The first systematic uncertainty is the statistical uncertainty and the second is the systematic.
Correlation matrix among the Higgs pT bins of the differential spectrum.
The inclusive cross section for top quark pair production is measured in proton-proton collisions at sqrt(s) = 7 and 8 TeV, corresponding to 5.0 and 19.7 invers-femtobarns, respectively, with the CMS experiment at the LHC. The cross sections are measured in the electron-muon channel using a binned likelihood fit to multi-differential final state distributions related to identified b quark jets and other jets in the event. The measured cross section values are 173.6 +/- 2.1 (stat) +4.5-4.0 (syst) +/- 3.8 (lumi) pb at sqrt(s) = 7 TeV, and 244.9 +/- 1.4 (stat) +6.3-5.5 (syst) +/- 6.4 (lumi) pb at sqrt(s) = 8 TeV, in good agreement with QCD calculations at next-to-next-to-leading-order accuracy. The ratio of the cross sections measured at 7 and 8 TeV is determined, as well as cross sections in the fiducial regions defined by the acceptance requirements on the two charged leptons in the final state. The cross section results are used to determine the top quark pole mass via the dependence of the theoretically predicted cross section on the mass, giving a best result of 173.8 +1.7-1.8 GeV. The data at sqrt(s) = 8 TeV are also used to set limits, for two neutralino mass values, on the pair production of supersymmetric top squarks with masses close to the top quark mass.
Measurement of the visible $t\bar{t}$ production cross-section in $pp$ collisions at $\sqrt{s} = 7$ and $8$ TeV. The visible cross section is defined for events containing an oppositely charged $\rm{e}\mu$ pair from the decay chain ${\rm t} \rightarrow {\rm W b} \rightarrow {\ell} \nu {\rm b}$ (including ${\rm W} \rightarrow \tau \nu \rightarrow {\ell} \nu \nu \nu$) and with both leptons satisfying $p_T > 20\, \rm{GeV}$ and $|{\eta}| < 2.4$.
Measurement of the inclusive $t\bar{t}$ production cross-section in $pp$ collisions at $\sqrt{s} = 7$ and $8$ TeV.
Top quark pole mass at NNLO+NNLL extracted by comparing the measured $t\bar{t}$ production cross sections at 7 and 8 TeV with predictions employing different PDF sets. The uncertainties of the CT14 PDF set are scaled to 68% confidence level.
The $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) production cross sections are measured using a data sample corresponding to an integrated luminosity of 35.8 $\pm$ 1.4 inverse picobarns of proton-proton collisions at $\sqrt{s}$ = 7 TeV, collected with the CMS detector at the LHC. The Upsilon resonances are identified through their decays to dimuons. Integrated over the $\Upsilon$ transverse momentum range $p_{t}^{\Upsilon} \lt$ 50GeV and rapidity range |$y^\Upsilon$| $\lt$ 2.4, and assuming unpolarized Upsilon production, the products of the Upsilon production cross sections and dimuon branching fractions are \begin{equation*}\sigma(pp \to \Upsilon(1S) X) . B(\Upsilon(1S) \to \mu^+ \mu^-) = (8.55 \pm 0.05^{+0.56}_{-0.50} \pm 0.34) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(2S) X) . B(\Upsilon(2S) \to \mu^+ \mu^-) = (2.21 \pm 0.03^{+0.16}_{-0.14} \pm 0.09) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(3S) X) . B(\Upsilon(3S) \to \mu^+ \mu^-) = (1.11 \pm 0.02^{+0.10}_{-0.08} \pm 0.04) nb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is from the uncertainty in the integrated luminosity. The differential cross sections in bins of transverse momentum and rapidity, and the cross section ratios are presented. Cross section measurements performed within a restricted muon kinematic range and not corrected for acceptance are also provided. These latter measurements are independent of Upsilon polarization assumptions. The results are compared to theoretical predictions and previous measurements.
The fiducial and acceptance-corrected cross sections for PT<50 GeV/c and |rapidity|<2.4.
The fiducial and acceptance corrected UPSI(1S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(1S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
The fiducial and acceptance corrected UPSI(2S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(2S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
The ratio of the top-quark branching fractions $R = B(t \to Wb)/B(t \to Wq)$, where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the $t\bar{t}$ dilepton final state with proton-proton collision data at $\sqrt{s}$ = 8 TeV from an integrated luminosity of 19.7 inverse-femtobarns, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R = 1.014 $\pm$ 0.003 (stat) $\pm$ 0.032 (syst) is measured, in good agreement with the standard model prediction. A lower limit R greater than 0.955 at the 95% confidence level is obtained after requiring R lower than one, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element |$V_tb$| greater than 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, $\Gamma_t$ = 1.36 $\pm$ 0.02 (stat)$^{+0.14}_{-0.11}$ (syst) GeV.
The measured TOP TOPBAR production cross section.
The measured ratio of branching fractions, R = BR(TOP --> W BOTTOM) / BR(TOP --> W QUARK) where the denominator includes the sum over all down-type quarks (QUARK = BOTTOM, STRANGE, DOWN). The combined measurement and the individual measurements from the three channels considered are presented.
An indirect measurement of the top-quark total decay width.
The ratio of the production cross sections times branching fractions (sigma(Bc+) B(Bc+ to J/psi pi+))/ (sigma(B+) B(B+ to J/psi K+)) is studied in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector at the LHC. The kinematic region investigated requires Bc+/- and B+/- mesons with transverse momentum pt > 15 GeV and rapidity abs(y) < 1.6. The data sample corresponds to an integrated luminosity of 5.1 inverse femtobarns. The ratio is determined to be [0.48 +/- 0.05 (stat) +/- 0.03 (syst) +/- 0.05 (tau_{Bc})]% The J/psi pi+/- pi+/- pi-/+ decay mode is also observed in the same data sample. Using a model-independent method developed to measure the efficiency given the presence of resonant behaviour in the three-pion system, the ratio of the branching fractions B(Bc+/- to J/psi pi+/- pi+/- pi-/+) / B(Bc+/- to J/psi pi+/-) is measured to be 2.55 +/- 0.80 (stat) +/- 0.33 (syst) +0.04/-0.01 (tau[Bc+]), consistent with the previous LHCb result.
The ratio of the production cross sections times branching fractions of $B_c^\pm\to J/\psi\pi^\pm$ and $B^\pm\to J/\psi K^\pm$ is measured in the kinematic region $p_T$> 15 GeV and |y| < 1.6. Beside the statistical and systematic errors, an uncertainty associated to the $B_c^{\pm}$ lifetime is quoted as a separate third error. The $B_c^\pm\to J/\psi\pi^\pm$ reconstruction efficiency has a dependence on the $B_c^\pm$ lifetime. Recently LHCb published a more precise $B_c^\pm$ lifetime measurement, which is significantly higher than the previous world average (PDG 2012). To determine the systematic uncertainty associated with the uncertainty in the $B_c^\pm$ lifetime, the efficiency is evaluated while changing the $B_c^\pm$ lifetime in the simulation to cover the range from the world average minus its one standard deviation uncertainty, to the new LHCb measurement. The resulting variation in the ratio is quoted separately as a lifetime systematic uncertainty ($\tau_{Bc}$). Charge conjugation is implied in the table.
To determine the systematic uncertainty in the ratio of branching fractions associated with the uncertainty in the $B_c^\pm$ lifetime, the efficiency is evaluated while changing the $B_c^\pm$ lifetime in the simulation to cover the range from the world average minus its one standard deviation uncertainty, to the new LHCb measurement. The resulting variation in the ratio is quoted separately as a lifetime systematic uncertainty ($\tau_{Bc}$). Charge conjugation is implied in the table.
A search for a heavy Higgs boson in the H to WW and H to ZZ decay channels is reported. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 19.7 inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the CERN LHC. Several final states of the H to WW and H to ZZ decays are analyzed. The combined upper limit at the 95% confidence level on the product of the cross section and branching fraction exclude a Higgs boson with standard model-like couplings and decays in the range 145 < m[H] < 1000 GeV. We also interpret the results in the context of an electroweak singlet extension of the standard model.
Upper limits at 95\% CL on the cross section for a heavy Higgs boson decaying to a pair of W bosons as a function of its mass and its width relative to a SM-like Higgs boson.
Upper limits at 95\% CL on the cross section for a heavy Higgs boson decaying to a pair of Z bosons as a function of its mass and its width relative to a SM-like Higgs boson.
Upper limits at 95% CL on the cross section for a heavy Higgs boson as a function of its mass and its width relative to a SM-like Higgs boson. Both, gluon-gluon fusion and VBF production processes are combined, assuming a SM-like ratio between the two.
The first observation of the Z boson decaying to four leptons in proton-proton collisions is presented. The analyzed data set corresponds to an integrated luminosity of 5.02 inverse femtobarns at sqrt(s) = 7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 sigma, is observed in the distribution of the invariant mass of four leptons (electrons and/or muons) with mass and width consistent with expectations for Z boson decays. The branching fraction and cross section reported here are defined by phase space restrictions on the leptons, namely, 80 < m[4l] < 100 GeV, where m[4l] is the invariant mass of the four leptons, and m[ll] > 4 GeV for all pairs of leptons, where m[ll] is the two-lepton invariant mass. The measured branching fraction is B(Z to 4l) = (4.2 /+0.9/-0.8 (stat.) +/- 0.2 (syst.)) 10E-6 and agrees with the standard model prediction of 4.45 10E-6. The measured cross section times branching fraction is sigma(pp to Z) B(Z to 4 l) = 112 +23/-20 (stat.) +7/-5 (syst.) +3/-2 (lumi.) fb, also consistent with the standard model prediction of 120 fb. The four-lepton mass peak arising from Z to 4 l decays provides a calibration channel for the Higgs boson search in the H to ZZ to 4 l decay mode.
The measured branching fraction Z->4l.
The measured Z->4l cross section times branching fraction. The (sys) error is the total systematic error, luminosity uncertainty is separated.
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