Measurements of luminosity obtained using the ATLAS detector during early running of the Large Ha... more Measurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at $\sqrt{s} = 7$ TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of the luminosities obtained from these methods are monitored as a function of time and of μ, the average number of inelastic interactions per bunch crossing. Residual time- and μ-dependence between the methods is less than 2% for 0<μ<2.5. Absolute luminosity calibrations, performed using beam separation scans, have a common systematic uncertainty of ±11%, dominated by the measurement of the LHC beam currents. After calibration, the luminosities obtained from the different methods differ by at most ±2%. The visible cross sections measured using the beam scans are compared to predictions obtained with the PYTHIA and PHOJET event generators and the ATLAS detector simulation.
The ATLAS trigger reduces the rate of interesting events to be recorded for off-line analysis in ... more The ATLAS trigger reduces the rate of interesting events to be recorded for off-line analysis in three successive levels from 40 MHz to 100 kHz, 2 kHz and 200 Hz. The high level triggers and data acquisition system are designed to profit from commodity computing and networking components to achieve the required performance. In this paper, we discuss data flow aspects of the design of the second level trigger (LVL2) and present results of performance measurements.
This work aims the recognition of characters in plates of private Brazilian vehicles using neural... more This work aims the recognition of characters in plates of private Brazilian vehicles using neural networks. Initially we define a standard for the image as prerequisite for the pre-processing. Afterward, the reduction of the dimensionality is made in order to make possible the use of the network. For this we establish a figure of merit -Q -characterizing, amongst some algorithms of characters splitting, the best one. Q is based on normalized cross correlation of the desired character image and the gotten one. The pre-processing allowed us the improvement of the image, reducing the background noise and increasing the contrast by applying a non-linear function. In the last stage, the neural network recognizes each character of the plate. Preliminary results are shown.
Search for supersymmetry using final states with one lepton, jets, and missing transverse momentu... more Search for supersymmetry using final states with one lepton, jets, and missing transverse momentum with the ATLAS detector in √ s = 7 TeV pp collisions
We present, in details, the principal component analysis (PCA) applied to a neural based recognit... more We present, in details, the principal component analysis (PCA) applied to a neural based recognition system. The technique is valuated on the extraction of principal components in character images of Brazilians' car license plates. This paper focus on the usage of the PCA in the recognition of character images. Comparisons with different neural classifiers are made.
In the paper, a hybrid image processing approach -the adaptive morphological Hough transform AMHT... more In the paper, a hybrid image processing approach -the adaptive morphological Hough transform AMHT -is developed and applied to detect straight line tracks in the volumetrical images produced by particle collisions in the ATLAS detector. The approach combines components of the adaptive Hough transform (i.e. the resolution refinement of the parameter space) and the morphological Hough transform (i.e. using a morphological mask to increase the chance for detecting the correct peak in Hough space). Experimental results show that the new AMHT method improves the detection efficiency from 86% to 89% while maintaining the timing requirements.
We present studies of W and Z bosons with associated high energy photons produced in pp collision... more We present studies of W and Z bosons with associated high energy photons produced in pp collisions at √ s = 7 TeV. The analysis uses 35 pb −1 of data collected by the ATLAS experiment in 2010. The event selection requires W and Z bosons decaying into high p T leptons (electrons or muons) and a photon with E T > 15 GeV separated from the lepton(s) by a distance ∆R(l, γ) > 0.7 in η-φ space. A total of 95 (97) pp → e ± νγ + X (pp → µ ± νγ + X) and 25 (23) pp → e + e − γ + X (pp → µ + µ − γ + X) event candidates are selected. The kinematic distributions of the leptons and photons and the production cross sections are measured. The data are found to agree with Standard Model predictions that include next-to-leading-order O(αα s ) contributions.
Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produc... more Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented.
The performance of a walkthrough over terrain models is deeply influenced by the real scenario hi... more The performance of a walkthrough over terrain models is deeply influenced by the real scenario high level of details. To guarantee natural and smooth changes in a sequence of scenes, it is necessary to display the actual height field's maps at interactive frame rates. These frame rates can be accomplished by reducing the number of rendered geometric primitives without compromising the visual quality. This paper describes an optimized algorithm for building a triangular mesh, the terrain model, which combines an efficient regular grid representation with low cost memory requirements, using a bottom-up approach.
A search for diphoton events with large missing transverse energy is presented. The data were col... more A search for diphoton events with large missing transverse energy is presented. The data were collected with the ATLAS detector in proton-proton collisions at ffiffi ffi s p ¼ 7 TeV at the CERN Large Hadron Collider and correspond to an integrated luminosity of 3:1 pb À1 . No excess of such events is observed above the standard model background prediction. In the context of a specific model with one universal extra dimension with compactification radius R and gravity-induced decays, values of 1=R < 729 GeV are excluded at 95% C. L., providing the most sensitive limit on this model to date.
Measurements are presented from proton-proton collisions at centre-of-mass energies of √ s = 0.9,... more Measurements are presented from proton-proton collisions at centre-of-mass energies of √ s = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase-space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections. The results are compared to each other and to various Monte Carlo models, including a new AMBT1 pythia6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the Monte Carlo models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with p T > 100 MeV, is measured to be 3.483 ± 0.009 (stat) ± 0.106 (syst) at √ s = 0.9 TeV and 5.630 ± 0.003 (stat) ± 0.169 (syst) at √ s = 7 TeV.
Measurement of the centrality dependence of J /ψ yields and observation of Z production in lead-l... more Measurement of the centrality dependence of J /ψ yields and observation of Z production in lead-lead collisions with the ATLAS detector at the LHC ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t Editor: H. Weerts Keywords: ATLAS LHC Heavy ions J /ψ Z boson Centrality dependence Using the ATLAS detector, a centrality-dependent suppression has been observed in the yield of J /ψ mesons produced in the collisions of lead ions at the Large Hadron Collider. In a sample of minimumbias lead-lead collisions at a nucleon-nucleon centre of mass energy √ s N N = 2.76 TeV, corresponding to an integrated luminosity of about 6.7 μb −1 , J /ψ mesons are reconstructed via their decays to μ + μ − pairs. The measured J /ψ yield, normalized to the number of binary nucleon-nucleon collisions, is found to significantly decrease from peripheral to central collisions. The centrality dependence is found to be qualitatively similar to the trends observed at previous, lower energy experiments. The same sample is used to reconstruct Z bosons in the μ + μ − final state, and a total of 38 candidates are selected in the mass window of 66 to 116 GeV. The relative Z yields as a function of centrality are also presented, although no conclusion can be inferred about their scaling with the number of binary collisions, because of limited statistics. This analysis provides the first results on J /ψ and Z production in lead-lead collisions at the LHC.
This Letter reports on a first measurement of the inclusive W +jets cross section in proton-proto... more This Letter reports on a first measurement of the inclusive W +jets cross section in proton-proton collisions at a centre-ofmass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and nextto-leading jets in the event. Measurements are also presented of the ratio of cross sections σ(W + ≥ n)/σ(W + ≥ n − 1) for inclusive jet multiplicities n = 1−4. The results, based on an integrated luminosity of 1.3 pb −1 , have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-to-leading order calculations, studied here for n ≤ 2, are found in good agreement with the data. Leading-order multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicities.
A measurement of the cross section for the inclusive production of isolated prompt photons in pp ... more A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a centre-of-mass energy √ s = 7 TeV is presented. The measurement covers the pseudorapidity ranges |η γ | < 1.37 and 1.52 ≤ |η γ | < 1.81 in the transverse energy range 15 ≤ E γ T < 100 GeV. The results are based on an integrated luminosity of 880 nb −1 , collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.
A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = ... more A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = 7 TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron e or muon µ) with large missing transverse energy and at least four jets, and dilepton (ee, µµ or eµ) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb −1 , 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-tt Standard Model processes are estimated using data-driven methods and determined to be 12.2 ± 3.9 events and 2.5 ± 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM tt production. The inclusive top quark pair production cross-section is measured to be
√ s = 7 TeV measured with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t... more √ s = 7 TeV measured with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t Dijet angular distributions from the first LHC pp collisions at center-of-mass energy √ s = 7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb −1 . Dijet χ distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the χ distributions excludes quark contact interactions with a compositeness scale Λ below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits. √ s = 7 TeV at the LHC. The data sample represents an integrated luminosity of 3.1 pb −1 , recorded in periods of stable collisions, through August 2010. The two distributions under
Jet cross sections have been measured for the first time in proton-proton collisions at a centreo... more Jet cross sections have been measured for the first time in proton-proton collisions at a centreof-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb −1 recorded at the Large Hadron Collider. The anti-kt algorithm is used to identify jets, with two jet resolution parameters, R = 0.4 and 0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sections are presented as functions of dijet mass and the angular variable χ. The results are compared to expectations based on next-to-leading-order QCD, which agree with the data, providing a validation of the theory in a new kinematic regime.
Measurements of luminosity obtained using the ATLAS detector during early running of the Large Ha... more Measurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at $\sqrt{s} = 7$ TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of the luminosities obtained from these methods are monitored as a function of time and of μ, the average number of inelastic interactions per bunch crossing. Residual time- and μ-dependence between the methods is less than 2% for 0<μ<2.5. Absolute luminosity calibrations, performed using beam separation scans, have a common systematic uncertainty of ±11%, dominated by the measurement of the LHC beam currents. After calibration, the luminosities obtained from the different methods differ by at most ±2%. The visible cross sections measured using the beam scans are compared to predictions obtained with the PYTHIA and PHOJET event generators and the ATLAS detector simulation.
The ATLAS trigger reduces the rate of interesting events to be recorded for off-line analysis in ... more The ATLAS trigger reduces the rate of interesting events to be recorded for off-line analysis in three successive levels from 40 MHz to 100 kHz, 2 kHz and 200 Hz. The high level triggers and data acquisition system are designed to profit from commodity computing and networking components to achieve the required performance. In this paper, we discuss data flow aspects of the design of the second level trigger (LVL2) and present results of performance measurements.
This work aims the recognition of characters in plates of private Brazilian vehicles using neural... more This work aims the recognition of characters in plates of private Brazilian vehicles using neural networks. Initially we define a standard for the image as prerequisite for the pre-processing. Afterward, the reduction of the dimensionality is made in order to make possible the use of the network. For this we establish a figure of merit -Q -characterizing, amongst some algorithms of characters splitting, the best one. Q is based on normalized cross correlation of the desired character image and the gotten one. The pre-processing allowed us the improvement of the image, reducing the background noise and increasing the contrast by applying a non-linear function. In the last stage, the neural network recognizes each character of the plate. Preliminary results are shown.
Search for supersymmetry using final states with one lepton, jets, and missing transverse momentu... more Search for supersymmetry using final states with one lepton, jets, and missing transverse momentum with the ATLAS detector in √ s = 7 TeV pp collisions
We present, in details, the principal component analysis (PCA) applied to a neural based recognit... more We present, in details, the principal component analysis (PCA) applied to a neural based recognition system. The technique is valuated on the extraction of principal components in character images of Brazilians' car license plates. This paper focus on the usage of the PCA in the recognition of character images. Comparisons with different neural classifiers are made.
In the paper, a hybrid image processing approach -the adaptive morphological Hough transform AMHT... more In the paper, a hybrid image processing approach -the adaptive morphological Hough transform AMHT -is developed and applied to detect straight line tracks in the volumetrical images produced by particle collisions in the ATLAS detector. The approach combines components of the adaptive Hough transform (i.e. the resolution refinement of the parameter space) and the morphological Hough transform (i.e. using a morphological mask to increase the chance for detecting the correct peak in Hough space). Experimental results show that the new AMHT method improves the detection efficiency from 86% to 89% while maintaining the timing requirements.
We present studies of W and Z bosons with associated high energy photons produced in pp collision... more We present studies of W and Z bosons with associated high energy photons produced in pp collisions at √ s = 7 TeV. The analysis uses 35 pb −1 of data collected by the ATLAS experiment in 2010. The event selection requires W and Z bosons decaying into high p T leptons (electrons or muons) and a photon with E T > 15 GeV separated from the lepton(s) by a distance ∆R(l, γ) > 0.7 in η-φ space. A total of 95 (97) pp → e ± νγ + X (pp → µ ± νγ + X) and 25 (23) pp → e + e − γ + X (pp → µ + µ − γ + X) event candidates are selected. The kinematic distributions of the leptons and photons and the production cross sections are measured. The data are found to agree with Standard Model predictions that include next-to-leading-order O(αα s ) contributions.
Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produc... more Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented.
The performance of a walkthrough over terrain models is deeply influenced by the real scenario hi... more The performance of a walkthrough over terrain models is deeply influenced by the real scenario high level of details. To guarantee natural and smooth changes in a sequence of scenes, it is necessary to display the actual height field's maps at interactive frame rates. These frame rates can be accomplished by reducing the number of rendered geometric primitives without compromising the visual quality. This paper describes an optimized algorithm for building a triangular mesh, the terrain model, which combines an efficient regular grid representation with low cost memory requirements, using a bottom-up approach.
A search for diphoton events with large missing transverse energy is presented. The data were col... more A search for diphoton events with large missing transverse energy is presented. The data were collected with the ATLAS detector in proton-proton collisions at ffiffi ffi s p ¼ 7 TeV at the CERN Large Hadron Collider and correspond to an integrated luminosity of 3:1 pb À1 . No excess of such events is observed above the standard model background prediction. In the context of a specific model with one universal extra dimension with compactification radius R and gravity-induced decays, values of 1=R < 729 GeV are excluded at 95% C. L., providing the most sensitive limit on this model to date.
Measurements are presented from proton-proton collisions at centre-of-mass energies of √ s = 0.9,... more Measurements are presented from proton-proton collisions at centre-of-mass energies of √ s = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase-space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections. The results are compared to each other and to various Monte Carlo models, including a new AMBT1 pythia6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the Monte Carlo models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with p T > 100 MeV, is measured to be 3.483 ± 0.009 (stat) ± 0.106 (syst) at √ s = 0.9 TeV and 5.630 ± 0.003 (stat) ± 0.169 (syst) at √ s = 7 TeV.
Measurement of the centrality dependence of J /ψ yields and observation of Z production in lead-l... more Measurement of the centrality dependence of J /ψ yields and observation of Z production in lead-lead collisions with the ATLAS detector at the LHC ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t Editor: H. Weerts Keywords: ATLAS LHC Heavy ions J /ψ Z boson Centrality dependence Using the ATLAS detector, a centrality-dependent suppression has been observed in the yield of J /ψ mesons produced in the collisions of lead ions at the Large Hadron Collider. In a sample of minimumbias lead-lead collisions at a nucleon-nucleon centre of mass energy √ s N N = 2.76 TeV, corresponding to an integrated luminosity of about 6.7 μb −1 , J /ψ mesons are reconstructed via their decays to μ + μ − pairs. The measured J /ψ yield, normalized to the number of binary nucleon-nucleon collisions, is found to significantly decrease from peripheral to central collisions. The centrality dependence is found to be qualitatively similar to the trends observed at previous, lower energy experiments. The same sample is used to reconstruct Z bosons in the μ + μ − final state, and a total of 38 candidates are selected in the mass window of 66 to 116 GeV. The relative Z yields as a function of centrality are also presented, although no conclusion can be inferred about their scaling with the number of binary collisions, because of limited statistics. This analysis provides the first results on J /ψ and Z production in lead-lead collisions at the LHC.
This Letter reports on a first measurement of the inclusive W +jets cross section in proton-proto... more This Letter reports on a first measurement of the inclusive W +jets cross section in proton-proton collisions at a centre-ofmass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and nextto-leading jets in the event. Measurements are also presented of the ratio of cross sections σ(W + ≥ n)/σ(W + ≥ n − 1) for inclusive jet multiplicities n = 1−4. The results, based on an integrated luminosity of 1.3 pb −1 , have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-to-leading order calculations, studied here for n ≤ 2, are found in good agreement with the data. Leading-order multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicities.
A measurement of the cross section for the inclusive production of isolated prompt photons in pp ... more A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a centre-of-mass energy √ s = 7 TeV is presented. The measurement covers the pseudorapidity ranges |η γ | < 1.37 and 1.52 ≤ |η γ | < 1.81 in the transverse energy range 15 ≤ E γ T < 100 GeV. The results are based on an integrated luminosity of 880 nb −1 , collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.
A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = ... more A measurement of the production cross-section for top quark pairs (tt) in pp collisions at √ s = 7 TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron e or muon µ) with large missing transverse energy and at least four jets, and dilepton (ee, µµ or eµ) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb −1 , 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-tt Standard Model processes are estimated using data-driven methods and determined to be 12.2 ± 3.9 events and 2.5 ± 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM tt production. The inclusive top quark pair production cross-section is measured to be
√ s = 7 TeV measured with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t... more √ s = 7 TeV measured with the ATLAS detector ✩ .ATLAS Collaboration a r t i c l e i n f o a b s t r a c t Dijet angular distributions from the first LHC pp collisions at center-of-mass energy √ s = 7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb −1 . Dijet χ distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the χ distributions excludes quark contact interactions with a compositeness scale Λ below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits. √ s = 7 TeV at the LHC. The data sample represents an integrated luminosity of 3.1 pb −1 , recorded in periods of stable collisions, through August 2010. The two distributions under
Jet cross sections have been measured for the first time in proton-proton collisions at a centreo... more Jet cross sections have been measured for the first time in proton-proton collisions at a centreof-mass energy of 7 TeV using the ATLAS detector. The measurement uses an integrated luminosity of 17 nb −1 recorded at the Large Hadron Collider. The anti-kt algorithm is used to identify jets, with two jet resolution parameters, R = 0.4 and 0.6. The dominant uncertainty comes from the jet energy scale, which is determined to within 7% for central jets above 60 GeV transverse momentum. Inclusive single-jet differential cross sections are presented as functions of jet transverse momentum and rapidity. Dijet cross sections are presented as functions of dijet mass and the angular variable χ. The results are compared to expectations based on next-to-leading-order QCD, which agree with the data, providing a validation of the theory in a new kinematic regime.
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Papers by Aline Gesualdi