Measurements of inclusive jet production are performed in $pp$ and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 $\mathrm{pb}^{-1}$ and 0.14 $\mathrm{nb}^{-1}$, respectively. The jets are identified with the anti-$k_t$ algorithm with $R=0.4$, and the spectra are measured over the kinematic range of jet transverse momentum $32 < p_{\mathrm{T}} < 500$ GeV, and absolute rapidity $|y| < 2.1$ and as a function of collision centrality. The nuclear modification factor, $R_{\mathrm{AA}}$, is evaluated and jets are found to be suppressed by approximately a factor of two in central collisions compared to $pp$ collisions. The $R_{\mathrm{AA}}$ shows a slight increase with $p_{\mathrm{T}}$ and no significant variation with rapidity.
The $\langle T_{\mathrm{AA}} \rangle $ and $\langle N_{\mathrm{part}} \rangle$ values and their uncertainties in each centrality bin.
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Double-differential three-jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV using the ATLAS detector at the Large Hadron Collider. The measurements are presented as a function of the three-jet mass $(m_{jjj})$, in bins of the sum of the absolute rapidity separations between the three leading jets $(|Y^\ast|)$. Invariant masses extending up to 5 TeV are reached for $8< |Y^\ast| < 10$. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of 4.51 fb$^{-1}$. Jets are identified using the anti-$k_t$ algorithm with two different jet radius parameters, R=0.4 and R=0.6. The dominant uncertainty in these measurements comes from the jet energy scale. Next-to-leading-order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. Good agreement is found between the data and the theoretical predictions based on most of the available sets of parton distribution functions, over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values.
Measured three-jet double-differential cross sections as a function of M(3JET) in |Y*|<2 for anti-kt R=0.4 jets. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
Measured three-jet double-differential cross sections as a function of M(3JET) in 2<=|Y*|<4 for anti-kt R=0.4 jets. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
Measured three-jet double-differential cross sections as a function of M(3JET) in 4<=|Y*|<6 for anti-kt R=0.4 jets. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
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.
Additional jet activity in dijet events is measured using $pp$ collisions at ATLAS at a centre-of-mass energy of 7 TeV, for jets reconstructed using the anti-kt algorithm with radius parameter R=0.6. This is done using variables such as the fraction of dijet events without an additional jet in the rapidity interval bounded by the dijet subsystem and correlations between the azimuthal angles of the dijets. They are presented, both with and without a veto on additional jet activity in the rapidity interval, as a function of the mean transverse momentum of the dijets and of the rapidity interval size. The double differential dijet cross section is also measured as a function of the interval size and the azimuthal angle between the dijets. These variables probe differences in the approach to resummation of large logarithms when performing QCD calculations. The data are compared to POWHEG, interfaced to the PYTHIA 8 and HERWIG parton shower generators, as well as to HEJ with and without interfacing it to the ARIADNE parton shower generator. None of the theoretical predictions agree with the data across the full phase-space considered; however, POWHEG+PYTHIA 8 and HEJ+ARIADNE are found to provide the best agreement with the data.These measurements use the full data sample collected with the ATLAS detector in 7 TeV $pp$ collisions at the LHC and correspond to integrated luminosities of 36.1 pb$^-1$ and 4.5 fb$^-1$ for data collected during 2010 and 2011 respectively.
Gap fraction as a function of leading dijet rapidity separation.
Gap fraction as a function of leading dijet scalar mean pT in GeV.
Mean number of jets in rapidity interval as a function of leading dijet rapidity separation.
The production of beauty and charm quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared 5 < Q^2 < 1000 GeV^2 using an integrated luminosity of 354 pb^{-1}. The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of Q^2, Bjorken x, jet transverse energy and pseudorapidity were measured and compared with next-to-leading-order QCD calculations. The beauty and charm contributions to the proton structure functions were extracted from the double-differential cross section as a function of x and Q^2. The running beauty-quark mass, m_b at the scale m_b, was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be 4.07 \pm 0.14 (fit} ^{+0.01}_{-0.07} (mod.) ^{+0.05}_{-0.00} (param.) ^{+0.08}_{-0.05} (theo) GeV.
Differential cross sections for inclusive jet production in beauty events as a function of ET(JET) for ET(JET) > 5 GeV. The measurements are given together with their statistical and systematic uncertainties. Hadronisation and QED radiative corrections, CHAD and CRAD, respectively, are also shown.
Differential cross sections for inclusive jet production in charm events as a function of ET(JET) for ET(JET) > 4.2 GeV. The measurements are given together with their statistical and systematic uncertainties. Hadronisation and QED radiative corrections, CHAD and CRAD, respectively, are also shown.
Differential cross sections for inclusive jet production in beauty events as a function of ETARAP(JET) for -1.6 < ETARAP(JET) < 2.2. The measurements are given together with their statistical and systematic uncertainties. Hadronisation and QED radiative corrections, CHAD and CRAD, respectively, are also shown.
The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.
Double differential cross section for Q^2=725 GeV^2.
Double differential cross section for Q^2=875 GeV^2.
Double differential cross section for Q^2=1025 GeV^2.
Double-differential dijet cross sections measured in pp collisions at the LHC with a 7 TeV centre-of-mass energy are presented as functions of dijet mass and rapidity separation of the two highest-pT jets. These measurements are obtained using data corresponding to an integrated luminosity of 4.5/fb, recorded by the ATLAS detector in 2011. The data are corrected for detector effects so that cross sections are presented at the particle level. Cross sections are measured up to 5 TeV dijet mass using jets reconstructed with the anti-kt algorithm for values of the jet radius parameter of 0.4 and 0.6. The cross sections are compared with next-to-leading-order perturbative QCD calculations by NLOJET++ corrected to account for non-perturbative effects. Comparisons with POWHEG predictions, using a next-to-leading-order matrix element calculation interfaced to a parton-shower Monte Carlo simulation, are also shown. Electroweak effects are accounted for in both cases. The quantitative comparison of data and theoretical predictions obtained using various parameterizations of the parton distribution functions is performed using a frequentist method. An example setting a lower limit on the compositeness scale for a model of contact interactions is presented, showing that the unfolded results can be used to constrain contributions to dijet production beyond that predicted by the Standard Model.
Measured double-differential dijet cross sections for the range 0.0 <= y* < 0.5 and jet radius parameter R = 0.4. The statistical uncertainties from data and MC simulation have been combined. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
Measured double-differential dijet cross sections for the range 0.5 <= y* < 1.0 and jet radius parameter R = 0.4. The statistical uncertainties from data and MC simulation have been combined. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
Measured double-differential dijet cross sections for the range 1.0 <= y* < 1.5 and jet radius parameter R = 0.4. The statistical uncertainties from data and MC simulation have been combined. The three columns correspond to nominal, stronger or weaker correlations between jet energy scale uncertainty components.
The production of $J/\psi$ mesons with rapidity $1.5<y<4.0$ or $-5.0<y<-2.5$ and transverse momentum $p_\mathrm{T}<14 \mathrm{GeV}/c$ is studied with the LHCb detector in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}=5 \mathrm{TeV}$. The analysis is based on a data sample corresponding to an integrated luminosity of about $1.6 \mathrm{nb}^{-1}$. For the first time the nuclear modification factor and forward-backward production ratio are determined separately for prompt $J/\psi$ mesons and $J/\psi$ from $b$-hadron decays. Clear suppression of prompt $J/\psi$ production with respect to proton-proton collisions at large rapidity is observed, while the production of $J/\psi$ from $b$-hadron decays is less suppressed. These results show good agreement with available theoretical predictions. The measurement shows that cold nuclear matter effects are important for interpretations of the related quark-gluon plasma signatures in heavy-ion collisions.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of transverse momentum in the FORWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of transverse momentum in the BACKWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
Single differential production cross sections of prompt J/PSI mesons and of J/PSI from B decay as a function of rapidity in the FORWARD region. The errors shown are statistical and the uncorrelated and correlated components of the systematic uncertainties.
The production cross-section of B+ mesons is measured as a function of transverse momentum pT and rapidity y in proton--proton collisions at center-of-mass energy sqrt(s) = 7 TeV, using 2.4 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9<pT<120 GeV and y<2.25, are compared to next-to-leading-order theoretical predictions.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range |y|<0.5. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 0.5<|y|<1. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 1<|y|<1.5 The first quoted uncertainty is statistical, the second uncertainty is systematic.
The production cross-sections of B mesons are measured in pp collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated luminosity of 0.36 fb-1. The B+, B0 and Bs0 mesons are reconstructed in the exclusive decays B+ -> J/psi K+, B0 -> J/psi K*0 and Bs0 -> J/psi phi, with J/psi -> mu+ mu-, K*0 -> K+ pi- and phi -> K+ K-. The differential cross-sections are measured as functions of B meson transverse momentum pT and rapidity y, in the range 0 < pT < 40 GeV/c and 2.0 < y < 4.5. The integrated cross-sections in the same pT and y ranges, including charge-conjugate states, are measured to be sigma(pp -> B+ + X) = 38.9 +- 0.3 (stat.) +- 2.5 (syst.) +- 1.3 (norm.) mub, sigma(pp -> B0 + X) = 38.1 +- 0.6 (stat.) +- 3.7 (syst.) +- 4.7 (norm.) mub, sigma(pp -> Bs0 + X) = 10.5 +- 0.2 (stat.) +- 0.8 (syst.) +- 1.0 (norm.) mub, where the third uncertainty arises from the pre-existing branching fraction measurements.
Integrated cross sections for B mesons in the defined kinematic range. The second (sys) uncertainty is the normalisation uncertainty arising from the pre-existing branching fraction measurements.
Double Differential distributions for B0 production.
Double differential distributions for B+ production.
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