Measurement of the high-mass Drell–Yan differential cross-section in pp collisions at with the ATLAS detector

This Letter reports a measurement of the high-mass Drell-Yan differential cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. Based on an integrated luminosity of 4.9 fb^-^1, the differential cross-section in the Z/@c^@?->e^+e^- channel is measured with the ATLAS detector as a function of the invariant mass, m_e_e, in the range 11625 GeV and pseudorapidity |@h|<2.5. A comparison is made to various event generators and to the predictions of perturbative QCD calculations at next-to-next-to-leading order.

Measurement of the differential cross-section of B⁺ meson production in pp collisions at sqrts = 7 TeV at ATLAS

The production cross-section of B+ mesons is measured as a function of transverse momentum p T and rapidity y in proton-proton collisions at centre-of-mass energy root 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 GeV < p(T) < 120 GeV and vertical bar y vertical bar < 2.25, are compared to next-to-leading-order theoretical predictions.

Measurement of the production cross section of jets in association with a Z boson in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

Measurements of the production of jets of particles in association with a Z boson in pp collisions at root s = 7 TeV are presented, using data corresponding to an integrated luminosity of 4.6 fb(-1) collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transverse momentum p(T) > 30 GeV and rapidity vertical bar y vertical bar < 4.4. The results are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators based on leading-order and next-to-leading-order matrix elements supplemented by parton showers.

Measurement of the inclusive jet cross section in pp collisions at sqrt(s)=2.76 TeV and comparison to the inclusive jet cross section at sqrt(s)=7 TeV using the ATLAS detector

The inclusive jet cross-section has been measured in proton-proton collisions at root s = 2.76 TeV in a dataset corresponding to an integrated luminosity of 0.20 pb(-1) collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-k(t) algorithm with two radius parameters of 0.4 and 0.6. The inclusive jet double-differential cross-section is presented as a function of the jet transverse momentum p(T) and jet rapidity y, covering a range of 20 <= p(T) < 430 GeV and vertical bar y vertical bar < 4.4. The ratio of the cross-section to the inclusive jet cross-section measurement at root s = 7 TeV, published by the ATLAS Collaboration, is calculated as a function of both transverse momentum and the dimensionless quantity x(T) = 2p(T)/root s, in bins of jet rapidity. The systematic uncertainties on the ratios are significantly reduced due to the cancellation of correlated uncertainties in the two measurements. Results are compared to the prediction from next-to-leading order perturbative QCD calculations corrected for non-perturbative effects, and next-to-leading order Monte Carlo simulation. Furthermore, the ATLAS jet cross-section measurements at root s = 2.76 TeV and root s = 7 TeV are analysed within a framework of next-to-leading order perturbative QCD calculations to determine parton distribution functions of the proton, taking into account the correlations between the measurements.

Measurement of the cross-section for W boson production in association with b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

This paper reports a measurement of the W+b-jets (W+b+X and W+b (b) over bar +X) production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. These results are based on data corresponding to an integrated luminosity of 4.6 fb(-1), collected with the ATLAS detector. Cross-sections are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for both the muon and electron decay modes of the W boson. The W+b-jets cross-section, corrected for all known detector effects, is quoted in a limited kinematic range. Combining the muon and electron channels, the fiducial cross-section for W+b-jets is measured to be 7.1 +/- 0.5 (stat) +/- 1.4 (syst) pb, consistent with the next-to-leading order QCD prediction, corrected for non-perturbative and double-parton interactions (DPI) contributions, of 4.70 +/- 0.09 (stat) (+0.60)(-0.49) (scale) +/- 0.06 (PDF) +/- 0.16 (non-pert) (+0.52)(-0.38) (DPI) pb.