A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ll gamma). The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120 < m[ll gamma] < 150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H to gamma* gamma to ll gamma, where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with m[H] = 125 GeV, a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9 +2.8/-1.8) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H to J/Psi gamma for the 125 GeV Higgs boson is set at 1.5E-3.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.
The cross section for the production of Z gamma in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 inverse femtobarns. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of Z Z gamma and Z gamma gamma are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.
Inclusive fiducial cross sections in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Fiducial cross sections with jet-veto in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Ratio of fiducial cross section with jet-veto and the inclusive cross section in bins of pT(gamma). The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
The double-differential cross sections of promptly produced J/psi and psi(2S) mesons are measured in pp collisions at sqrt(s) = 7 TeV, as a function of transverse momentum pt and absolute rapidity abs(y). The analysis uses J/psi and psi(2S) dimuon samples collected by CMS, corresponding to integrated luminosities of 4.55 and 4.90 inverse femtobarns, respectively. The results are based on a two-dimensional analysis of the dimuon invariant mass and decay length, and extend to pt = 120 and 100 GeV for the J/psi and psi(2S), respectively, when integrated over the interval abs(y) < 1.2. The ratio of the psi(2S) to J/psi cross sections is also reported for abs(y) < 1.2, over the range 10 < pt < 100 GeV. These are the highest pt values for which the cross sections and ratio have been measured.
J/psi double-differential cross section times branching fraction assuming unpolarized production as a function of pT and y for 0.0 < |y| < 0.3, 0.3 < |y| < 0.6, 0.6 < |y| < 0.9 and 0.9 < |y| < 1.2.
psi(2S) double-differential cross section times branching fraction assuming unpolarized production as a function of pT and y for 0.0 < |y| < 0.3, 0.3 < |y| < 0.6, 0.6 < |y| < 0.9 and 0.9 < |y| < 1.2.
J/psi double-differential cross section times branching fraction and the corresponding scaling factors to obtain the cross sections for different polarization scenarios (azimuthal polarization parameter in the center of mass helicity frame lambda_theta^HX = +1, -1, +0.1) as a function of pT for |y| < 1.2.
We present a measurement of the cross sections for the associated production of a $W$ boson with at least one heavy quark jet, $b$ or $c$, in proton-antiproton collisions. Data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ recorded with the D0 detector at the Fermilab Tevatron \ppbar Collider at $\sqrt{s}=1.96$ TeV are used to measure the cross sections differentially as a function of the jet transverse momenta in the range 20 to 150 GeV. These results are compared to calculations of perturbative QCD theory as well as predictions from Monte Carlo generators.
The $W + b$-jet production cross sections times $W \to \mu\nu$ branching fraction, ${\rm d}\sigma/{\rm d}p_T^{\rm jet}$.
The $W + c$-jet production cross sections times $W \to \mu\nu$ branching fraction, ${\rm d}\sigma/{\rm d}p_T^{\rm jet}$.
The $\sigma(W+c)/\sigma(W+b)$ cross section ratio in bins of $c(b)$-jet $p_T$.
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.
We present the first measurements of the differential cross section $d\sigma/dp_{T}^{\gamma}$ for the production of an isolated photon in association with at least two $b$-quark jets. The measurements consider photons with rapidities $|y^\gamma| < 1.0$ and transverse momenta $30 < p_{T}^{\gamma} < 200$~\GeV. The $b$-quark jets are required to have $p_T^{jet}>15$ GeV and $| y^{jet}| < 1.5$. The ratio of differential production cross sections for $\gamma+2~b$-jets to $\gamma+b$-jet as a function of $p_{T}^{\gamma}$ is also presented. The results are based on the proton-antiproton collision data at $\sqrt{s}=$1.96~\TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the $k_{T}$-factorization approach and those from the SHERPA and PYTHIA Monte Carlo event generators.
The differential GAMMA+2BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The differential GAMMA+BJET production cross section, DSIG/DPT(GAMMA), in bins of PT(GAMMA).
The SIG(GAMMA 2BJET)/SIG(GAMMA BJET) cross section ratio in bins of PT(GAMMA).
A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a $b\bar{b}$ quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 inverse femtobarns. Certain channels include data from 7 TeV collisions corresponding to an integrated luminosity of 4.9 inverse femtobarns. The searches are sensitive to non-standard-model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at $m_H$=125 GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.
Summary of 95% CL upper limits on SIG*BR(HIGGS --> INVISIBLE)/SIG(SM) obtained from the VBF search, the combined ZH searches, and the combination of all three searches.
Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at sqrt(s) = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 inverse femtobarns recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop (t-bar), in final states with a muon or an electron. The measured inclusive t-channel cross section is sigma[t-ch] = 83.6 +/- 2.3 (stat.) +/- 7.4 (syst.) pb. The single t and t-bar cross sections are measured to be sigma[t-ch,t] = 53.8 +/- 1.5 (stat.) +/- 4.4 (syst.) pb and sigma[t-ch,t-bar] = 27.6 +/- 1.3 (stat.) +/- 3.7 (syst.) pb, respectively. The measured ratio of cross sections is R[t-ch] = sigma[t-ch,t]/sigma[t-ch,t-bar] = 1.95 +/- 0.10 (stat.) +/- 0.19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vtb is extracted and, in combination with a previous CMS result at sqrt(s) = 7 TeV, a value abs(Vtb) = 0.998 +/- 0.038 (exp.) +/- 0.016 (theo.) is obtained.
The measured inclusive single-top-quark production cross section and the separate single top-quark and top-antiquark production cross sections in the t-channel.
The ratio of the inclusive single-top-quark production cross section in the t-channel at 8 TeV to the cross section at 7 TeV.
The ratio of the top-quark production cross section in the t-channel to the top-antiquark production cross section in the t-channel.
The production of a Z boson, decaying into two leptons and produced in association with one or more b jets, is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV. The data were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 5 inverse femtobarns. The Z(ll) + b-jets cross sections (where ll = mu mu or ee) are measured separately for a Z boson produced with exactly one b jet and with at least two b jets. In addition, a cross section ratio is extracted for a Z boson produced with at least one b jet, relative to a Z boson produced with at least one jet. The measured cross sections are compared to various theoretical predictions, and the data favour the predictions in the five-flavour scheme, where b quarks are assumed massless. The kinematic properties of the reconstructed particles are compared with the predictions from the MADGRAPH event generator using the PYTHIA parton shower simulation.
The cross section at the particle level for the production of a Z boson with exactly one b-jet.
The cross section at the particle level for the production of a Z boson with at least two b-jets.
The cross section at the particle level for the production of a Z boson with at least one b-jet.
A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV is reported. Jets are reconstructed from charged particles using the anti-$k_{\rm T}$ jet algorithm with jet resolution parameters $R$ of $0.2$ and $0.3$ in pseudo-rapidity $|\eta|<0.5$. The transverse momentum $p_{\rm T}$ of charged particles is measured down to $0.15$ GeV/$c$ which gives access to the low $p_{\rm T}$ fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter $R=0.3$ considered in the analysis. The fragmentation bias introduced by selecting jets with a high $p_{\rm T}$ leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with $R=0.2$ and $R=0.3$ is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with $R<0.3$.
Average values of the number of participating nucleons (Npart), number of binary collisions (Ncoll), and the nuclear overlap function (TAA) for the centrality intervals used in the jet analysis.
Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 0-10%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.
Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 10-30%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.
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