The production cross sections of the inclusive Drell-Yan processes W to l nu and Z/gamma to ll (l=e,mu) are measured in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector. The cross sections are reported integrated over a fiducial kinematic range, extrapolated to the full range and also evaluated differentially as a function of the W decay lepton pseudorapidity and the Z boson rapidity, respectively. Based on an integrated luminosity of about 35 pb^-1 collected in 2010, the precision of these measurements reaches a few per cent. The integrated and the differential W+- and Z/gamma cross sections in the e and mu channels are combined, and compared with perturbative QCD calculations, based on a number of different parton distribution sets available at NNLO.
Theory prediction from FEWZ program at NNLO QCD for fiducial Z0 production cross section times leptonic branching using different PDF sets. The first error (stat) is the numerical statistical uncertainty of the calculation, while second and third give the asymmetric uncertainty from the PDF set.
Theory prediction from FEWZ program at NNLO QCD for total Z0 production cross section times leptonic branching using different PDF sets. The first error (stat) is the numerical statistical uncertainty of the calculation, while second and third give the asymmetric uncertainty from the PDF set.
Theory prediction from FEWZ program at NNLO QCD for fiducial W+ + W- production cross section times leptonic branching using different PDF sets. The first error (stat) is the numerical statistical uncertainty of the calculation, while second and third give the asymmetric uncertainty from the PDF set.
The production of a W boson in association with a single charm quark is studied using 4.6 fb^-1 of pp collision data at sqrt(s)=7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96 +0.26 -0.30 at Q^2=1.9 GeV^2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio sigma(W^+ + bar{c})/sigma(W^- + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s-bar{s} quark asymmetry.
Measured integrated cross sections of the production of a W boson with a single c-jet, a D meson or a D* meson times the branching ratio W -> l nu in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. Jets are not required for the W+D/D* cross sections. The cross sections are defined for OS-SS events.
Measured integrated cross section ratios of the production of W+ and W- bosons associated with a single c-jet, a D meson or a D* meson in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. Jets are not required for the W+D/D* cross sections. The cross sections are defined for OS-SS events.
Measured differential cross sections as function of the lepton pseudo-rapidity of the production of a W boson with a single c-jet times the branching ratio W -> l nu in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. The cross sections are defined for OS-SS events.
A measurement of the cross section for the production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The results are based on an integrated luminosity of 4.6 fb-1 collected with the ATLAS detector at the LHC. The cross section is measured as a function of photon pseudorapidity and transverse energy in the kinematic range between 100 GeV and 1000 GeV and in the regions of pseudorapidity less than 1.37 and between 1.52 and 2.37. The results are compared to leading-order parton-shower Monte Carlo models and next-to-leading-order perturbative QCD calculations. Next-to-leading-order perturbative QCD calculations agree well with the measured cross sections as a function of transverse energy and pseudorapidity.
Measured inclusive prompt photon production cross section in the pseudorapidity range |eta^gamma| < 1.37 as a function of E_T^gamma with statistical and systematic uncertainties.
Measured inclusive prompt photon production cross section in the pseudorapidity range |eta^gamma| 1.52-2.37 as a function of E_T^gamma with statistical and systematic uncertainties.
Measured inclusive prompt photon production cross section in the ET_gamma region > 100 GeV as a function of |eta(gamma)| with statistical and systematic uncertainties.
The production of $D^{*\pm}$, $D^\pm$ and $D_s^\pm$ charmed mesons has been measured with the ATLAS detector in $pp$ collisions at $\sqrt{s}=7$ TeV at the LHC, using data corresponding to an integrated luminosity of $280\,$nb$^{-1}$. The charmed mesons have been reconstructed in the range of transverse momentum $3.5<p_{\rm T}(D)<100$ GeV and pseudorapidity $|\eta(D)|<2.1$. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for $D^{*\pm}$ and $D^\pm$ production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible $D$ cross sections and an extrapolation to the full kinematic phase space, the strangeness-suppression factor in charm fragmentation, the fraction of charged non-strange $D$ mesons produced in a vector state, and the total cross section of charm production at $\sqrt{s}=7$ TeV were derived.
The visible low-$p_T$, $3.5<p_T(D)<20\rm{\ GeV}$, and high-$p_T$, $20<p_T(D)<100\rm{\ GeV}$, cross sections of $D^{*\pm}$, $D^\pm$ and $D^\pm_s$ production with $|\eta|<2.1$. The data uncertainties are the total uncertainties obtained as sums in quadrature of the statistical, systematic, luminosity and branching-fraction uncertainties.
The measured differential cross sections $\rm{d}\sigma/\rm{d}p_T$ of $D^{*\pm}$ and $D^\pm$ production with $|\eta|<2.1$. The first and second errors are the statistical and systematic uncertainties, respectively. The systematic uncertainties corresponding to the tracking ($\delta_2$) uncertainties (Table 2 of the paper) are strongly correlated. The fully correlated uncertainties linked with the luminosity measurement ($3.5\%$) and branching fractions ($1.5\%$ and $2.1\%$ for $D^{*\pm}$ and $D^\pm$, respectively) are not shown.
The measured differential cross sections $\rm{d}\sigma/\rm{d}|\eta|$ of $D^{*\pm}$ and $D^\pm$ production with $3.5<p_T<20\,$GeV. The first and second errors are the statistical and systematic uncertainties, respectively. The systematic uncertainty fractions corresponding to the tracking ($\delta_2$) uncertainties (Table 2 of the paper) are strongly correlated. The fully correlated uncertainties linked with the luminosity measurement ($3.5\%$) and branching fractions ($1.5\%$ and $2.1\%$ for $D^{*\pm}$ and $D^\pm$, respectively) are not shown.
The production of two high-p_T jets in the interactions of quasi-real photons in e+e- collisions at sqrt{s_ee} from 189 GeV to 209 GeV is studied with data corresponding to an integrated e+e- luminosity of 550 pb^{-1}. The jets reconstructed by the k_T cluster algorithm are defined within the pseudo-rapidity range -1 < eta < 1 and with jet transverse momentum, p_T, above 3 GeV/c. The differential di-jet cross-section is measured as a function of the mean transverse momentum ptmean of the jets and is compared to perturbative QCD calculations.
Total cross section for dijet production. Errors are combined statistics and systematics.
Measured dijet production cross section as a function of the mean jet transverse momentum. Errors include both statistics and systematics.
Measured dijet production cross section as a function of jet pseudorapiditydifference. Errors include both statistics and systematics.
Results are presented from the first p p colliding beam runs at the CERN ISR, using the UA5 streamer chamber detector. p p interactions at s = 53 GeV are compared with pp data taken in the same experiment. The results are in good agreement with extrapolations of low-energy p p data.
No description provided.
MOMENTS OF MULTIPLICITY DISTRIBUTIONS FOR P P AND P AP. MULT(NAME=DQ) IS <(N-<N>)**Q>**1/Q. MULT(NAME=NQ) IS <N**Q>.
We present cross section measurements for inclusive jet production in almost-real photon-photon interactions at TRISTAN using the AMY detector. The results are compared with leading-order QCD calculations for different parameterizations of the parton density in the photon.
No description provided.
No description provided.
No description provided.
Inclusive production of $\mathrm{D^{*\pm}}$ mesons in two-photon collisions was measured by the L3 experiment at LEP. The data were collected at a centre-of-mass energy $\sqrt{s} = 189$ GeV with an integrated luminosity of $176.4 \mathrm{pb^{-1}}$. Differential cross sections of the process $\mathrm{e^+e^- \to D^{*\pm} X}$ are determined as functions of the transverse momentum and pseudorapidity of the $\mathrm{D^{*\pm}}$ mesons in the kinematic region 1 GeV $< p_{T}^{\mathrm{D^*}} < 5 $ GeV and $\mathrm{|\eta^{D^*}|} < 1.4$. The cross section integrated over this phase space domain is measured to be $132 \pm 22(stat.) \pm 26(syst.)$ pb. The differential cross sections are compared with next-to-leading order perturbative QCD calculations.
The measured cross sections, as a function of PT over the bin ranges and the differential cross sections after bin-centre corrections.
The measured cross sections, as a function of pseudorapidity over the bin ranges and the differential cross sections after bin-centre corrections.
Integrated cross section in the visible kinematic region.
High transverse momentum pi0-mesons have been measured with the H1 detector at HERA in deep-inelastic ep scattering events at low Bjorken-x, down to x <~ 4.10^{-5}. The measurement is performed in a region of small angles with respect to the proton remnant in the laboratory frame of reference, namely the forward region, and corresponds to central rapidity in the centre of mass system of the virtual photon and proton. This region is expected to be particularly sensitive to QCD effects in hadronic final states. Differential cross-sections for inclusive pi0-meson production are presented as a function of Bjorken-x and the four-momentum transfer Q^2, and as a function of transverse momentum and pseudorapidity. A recent numerical BFKL calculation and predictions from QCD models based on DGLAP parton evolution are compared with the data.
Axis error includes +- 5/5 contribution (Trigger efficiency).
Axis error includes +- 5/5 contribution (Trigger efficiency).
Axis error includes +- 5/5 contribution (Trigger efficiency).
The production of isolated photons in deep-inelastic scattering $ep\to e \gamma X$ is measured with the H1 detector at HERA. The measurement is performed in the kinematic range of negative four-momentum transfer squared $4<Q^2<150 $~GeV$^2$ and a mass of the hadronic system $W_X>50$ GeV. The analysis is based on a total integrated luminosity of 227~pb$^{-1}$. The production cross section of isolatedphotons with a transverse energy in the range $3 < E_T^\gamma < 10$ GeV and pseudorapidity range $-1.2 < \eta^\gamma < 1.8$ is measured as a function of $E_T^\gamma$, $\eta^\gamma$ and $Q^2$. Isolated photon cross sections are also measured for events with no jets or at least one hadronic jet. The measurements are compared with predictions from Monte Carlo generators modelling the photon radiation from the quark and the electron lines, as well as with calculations at leading and next to leading order in the strong coupling. The predictions significantly underestimate the measured cross sections.
Measured inclusive isolated photon cross section.
Measured total cross section for isolated photons plus no-jets and 1-jet.
Differential cross section as a function of the photon ET.
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