The differential charged jet cross sections, jet fragmentation distributions, and jet shapes are measured in minimum bias proton-proton collisions at centre-of-mass energy $\sqrt{s}=7$ TeV using the ALICE detector at the LHC. Jets are reconstructed from charged particle momenta in the mid-rapidity region using the sequential recombination $k_{\rm T}$ and anti-$k_{\rm T}$ as well as the SISCone jet finding algorithms with several resolution parameters in the range $R=0.2$ to $0.6$. Differential jet production cross sections measured with the three jet finders are in agreement in the transverse momentum ($p_{\rm T}$) interval $20
Measured charged jet differential cross sections for INEL proton-proton collisions at $\sqrt{s}$ = 7 TeV.
Measured charged jet differential cross sections for INEL proton-proton collisions at $\sqrt{s}$ = 7 TeV.
Measured charged jet differential cross sections for INEL proton-proton collisions at $\sqrt{s}$ = 7 TeV.
The inclusive jet cross-section is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5 fb$^{-1}$ collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-$k_t$ algorithm with radius parameter values of 0.4 and 0.6. The double-differential cross-sections are presented as a function of the jet transverse momentum and the jet rapidity, covering jet transverse momenta from 100 GeV to 2 TeV. Next-to-leading-order QCD calculations corrected for non-perturbative effects and electroweak effects, as well as Monte Carlo simulations with next-to-leading-order matrix elements interfaced to parton showering, are compared to the measured cross-sections. A quantitative comparison of the measured cross-sections to the QCD calculations using several sets of parton distribution functions is performed.
Measured double-differential inclusive-jet cross section for the range 0.0 <= |y| < 0.5 and for anti-kT jets with radius parameter R = 0.4. It is based on the data sample of proton-proton collisions at 7 TeV of centre-of-mass energy collected in 2011 by the ATLAS experiment at the LHC. The data sample corresponds to the integrated luminosity of 4.5 fb^-1. The statistical uncertainties arising from data and MC simulation have been combined. All the components of the systematic uncertainty are shown. They are: all the components of the jet energy scale uncertainty (jesX), the uncertainty of the jet energy resolution (jer), the uncertainty of the jet angular resolution (jar), the uncertainty of data unfolding (unfold), the uncertainty of the jet quality selection (qual), the luminosity uncertainty (lumi). All the components are assumed to be independent of each other. Each component is assumed to be fully correlated in pT and eta. Concerning the shape of the different components, Gaussian distribution assumption works for most of them. The three columns correspond to three different sets of the systematic uncertainty built with nominal, stronger or weaker assumptions on correlations between the jet energy scale uncertainty components. For more information on the systematic uncertainties, see the reference paper.
Measured double-differential inclusive-jet cross section for the range 0.5 <= |y| < 1.0 and for anti-kT jets with radius parameter R = 0.4. It is based on the data sample of proton-proton collisions at 7 TeV of centre-of-mass energy collected in 2011 by the ATLAS experiment at the LHC. The data sample corresponds to the integrated luminosity of 4.5 fb^-1. The statistical uncertainties arising from data and MC simulation have been combined. All the components of the systematic uncertainty are shown. They are: all the components of the jet energy scale uncertainty (jesX), the uncertainty of the jet energy resolution (jer), the uncertainty of the jet angular resolution (jar), the uncertainty of data unfolding (unfold), the uncertainty of the jet quality selection (qual), the luminosity uncertainty (lumi). All the components are assumed to be independent of each other. Each component is assumed to be fully correlated in pT and eta. Concerning the shape of the different components, Gaussian distribution assumption works for most of them. The three columns correspond to three different sets of the systematic uncertainty built with nominal, stronger or weaker assumptions on correlations between the jet energy scale uncertainty components. For more information on the systematic uncertainties, see the reference paper.
Measured double-differential inclusive-jet cross section for the range 1.0 <= |y| < 1.5 and for anti-kT jets with radius parameter R = 0.4. It is based on the data sample of proton-proton collisions at 7 TeV of centre-of-mass energy collected in 2011 by the ATLAS experiment at the LHC. The data sample corresponds to the integrated luminosity of 4.5 fb^-1. The statistical uncertainties arising from data and MC simulation have been combined. All the components of the systematic uncertainty are shown. They are: all the components of the jet energy scale uncertainty (jesX), the uncertainty of the jet energy resolution (jer), the uncertainty of the jet angular resolution (jar), the uncertainty of data unfolding (unfold), the uncertainty of the jet quality selection (qual), the luminosity uncertainty (lumi). All the components are assumed to be independent of each other. Each component is assumed to be fully correlated in pT and eta. Concerning the shape of the different components, Gaussian distribution assumption works for most of them. The three columns correspond to three different sets of the systematic uncertainty built with nominal, stronger or weaker assumptions on correlations between the jet energy scale uncertainty components. For more information on the systematic uncertainties, see the reference paper.
The production of a $W$ boson decaying to $e\nu$ or $\mu\nu$ in association with a $W$ or $Z$ boson decaying to two jets is studied using $4.6 \mathrm{fb}^{-1}$ of proton--proton collision data at $\sqrt{\rm{s}} = 7$ TeV recorded with the ATLAS detector at the LHC. The combined $WW+WZ$ cross section is measured with a significance of 3.4$\sigma$ and is found to be $68 \pm 7 \ \mathrm{(stat.)} \pm 19 \ \mathrm{(syst.)} \ pb$, in agreement with the Standard Model expectation of $61.1 \pm 2.2 \ \mathrm{pb}$. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.
The total and fiducial cross sections for the production of W(LEPTON NU) W(JET JET) or W(LEPTON NU) Z(JET JET). The cross sections are the sum of the WW and WZ processes.
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.
This paper presents cross sections for the production of a W boson in association with jets, measured in proton--proton collisions at $\sqrt{s}=7$ TeV with the ATLAS experiment at the Large Hadron Collider. With an integrated luminosity of $4.6 fb^{-1}$, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of 1 TeV and multiplicities up to seven associated jets. The production cross sections for W bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. The measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.
Distribution of inclusive jet multiplicity.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the electron channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the muon channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
The production of the $\eta_c (1S)$ state in proton-proton collisions is probed via its decay to the $p \bar{p}$ final state with the LHCb detector, in the rapidity range $2.0 < y < 4.5$ and in the meson transverse-momentum range $p_T > 6.5$ GeV/c. The cross-section for prompt production of $\eta_c (1S)$ mesons relative to the prompt $J/\psi$ cross-section is measured, for the first time, to be $\sigma_{\eta_c (1S)}/\sigma_{J/\psi} = 1.74 \pm 0.29 \pm 0.28 \pm 0.18 _{B}$ at a centre-of-mass energy $\sqrt{s} = 7$ TeV using data corresponding to an integrated luminosity of 0.7 fb$^{-1}$, and $\sigma_{\eta_c (1S)}/\sigma_{J/\psi} = 1.60 \pm 0.29 \pm 0.25 \pm 0.17 _{B}$ at $\sqrt{s} = 8$ TeV using 2.0 fb$^{-1}$. The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the $\eta_c (1S)$ and $J/\psi$ decays to the $p \bar{p}$ final state. In addition, the inclusive branching fraction of $b$-hadron decays into $\eta_c (1S)$ mesons is measured, for the first time, to be $B ( b \rightarrow \eta_c X ) = (4.88 \pm 0.64 \pm 0.29 \pm 0.67 _{B}) \times 10^{-3}$, where the third uncertainty includes also the uncertainty on the $J/\psi$ inclusive branching fraction from $b$-hadron decays. The difference between the $J/\psi$ and $\eta_c (1S)$ meson masses is determined to be $114.7 \pm 1.5 \pm 0.1$ MeV/c$^2$.
Differential cross-section for $\eta_c(1S)$ prompt production for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.
Differential cross-section for $\eta_c(1S)$ prompt production for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.
Differential cross-section for $\eta_c(1S)$ from inclusive charmonium production in b-hadrons decays for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.
The production of $\chi_b$ mesons in proton-proton collisions is studied using a data sample collected by the LHCb detector, at centre-of-mass energies of $\sqrt{s}=7$ and $8$ TeV and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $\chi_b$ mesons are identified through their decays to $\Upsilon(1S)\gamma$ and $\Upsilon(2S)\gamma$ using photons that converted to $e^+e^-$ pairs in the detector. The relative prompt production rate of $\chi_{b1}(1P)$ and $\chi_{b2}(1P)$ mesons is measured as a function of the $\Upsilon(1S)$ transverse momentum in the $\chi_b$ rapidity range $2.0
Relative production cross section of $\chi_{b2}(1P)$ to $\chi_{b1}(1P)$ mesons in $p_T$ bins of $\Upsilon(1S)$ meson. The first uncertainty is statistical, the second is systematic and the third is due to the uncertainty on the branching fractions.
A measurement of the production processes of the recently discovered Higgs boson is performed in the two-photon final state using 5.4 fb$^{-1}$ of proton-proton collisions data at $\sqrt{s}=7$ TeV and 20.3 fb$^{-1}$ at $\sqrt{s}=8$ TeV collected by the ATLAS detector at the Large Hadron Collider. The number of observed Higgs boson decays to diphotons divided by the corresponding Standard Model prediction, called the signal strength, is found to be $\mu = 1.17 \pm 0.27$ at the value of the Higgs boson mass measured by ATLAS, $m_{H}$ = 125.4 GeV. The analysis is optimized to measure the signal strengths for individual Higgs boson production processes at this value of $m_{H}$. They are found to be $\mu_{\mathrm{ggF}} = 1.32 \pm 0.38$, $\mu_{\mathrm{VBF}} = 0.8 \pm 0.7$, $\mu_{{WH}} = 1.0 \pm 1.6 $, $\mu_{{ZH}} = 0.1 ^{+3.7}_{-0.1} $, $\mu_{{t\bar{t}H}} = 1.6 ^{+2.7}_{-1.8} $, for Higgs boson production through gluon fusion, vector-boson fusion, and in association with a $W$ or $Z$ boson or a top-quark pair, respectively. Compared with the previously published ATLAS analysis, the results reported here also benefit from a new energy calibration procedure for photons and the subsequent reduction of the systematic uncertainty on the diphoton mass resolution. No significant deviations from the predictions of the Standard Model are found.
The signal strength for a Higgs boson of mass mH = 125.4 GeV decaying via H->gammagamma as measured in the individual analysis categories, and the combined signal strength, for the combination of the 7 TeV and 8 TeV data. The VH dilepton category is not shown because with only two events in the combined sample, the fit results are not meaningful.
The signal strength for a Higgs boson of mass mH = 125.4 GeV decaying via H->gammagamma as measured in groups of categories sensitive to individual production modes, and the combined signal strength, for the combination of the 7 TeV and 8 TeV data.
Measured signal strengths, for a Higgs boson of mass mH = 125.4 GeV decaying via H->gammagamma, of the different Higgs boson production modes and the combined signal strength mu obtained with the combination of the 7 TeV and 8 TeV data.
The ratio of the production cross sections for W and Z bosons in association with jets has been measured in proton-proton collisions at $\sqrt{s}$ = 7 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6 fb$^{-1}$. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum $p_T$ > 30 GeV and jet rapidity $|y|$ < 4.4. The measurements are compared to next-to-leading-order perturbative QCD calculations and to predictions from different Monte Carlo generators implementing leading-order matrix elements supplemented by parton showers.
Distribution of inclusive jet multiplicity.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the electron channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
Breakdown of systematic uncertainties in percent in inclusive jet multiplicity in the muon channel.Uncertainties have been symmetrised and the sign denotes the sign of the original up-variation.
A measurement of the total $pp$ cross section at the LHC at $\sqrt{s}=7$ TeV is presented. In a special run with high-$\beta^{\star}$ beam optics, an integrated luminosity of 80 $\mu$b$^{-1}$ was accumulated in order to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable $t$. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the $|t|$ range from 0.01 GeV$^2$ to 0.1 GeV$^2$ to extrapolate to $|t|\rightarrow 0$, the total cross section, $\sigma_{\mathrm{tot}}(pp\rightarrow X)$, is measured via the optical theorem to be: $$\sigma_{\mathrm{tot}}(pp\rightarrow X) = 95.35 \; \pm 0.38 \; ({\mbox{stat.}}) \pm 1.25 \; ({\mbox{exp.}}) \pm 0.37 \; (\mbox{extr.}) \; \mbox{mb},$$ where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation to $|t|\rightarrow 0$. In addition, the slope of the elastic cross section at small $|t|$ is determined to be $B = 19.73 \pm 0.14 \; ({\mbox{stat.}}) \pm 0.26 \; ({\mbox{syst.}}) \; \mbox{GeV}^{-2}$.
The measured total cross section, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The nuclear slope of the differential eslastic cross section at small |t|, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The Optical Point dsigma/(elastic)/dt(t-->0), the total elastic cross section and the observed elastic cross section within the fiducial volume. The first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
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