1,771 research outputs found

    Latest jets results from the LHC

    Full text link
    A fundamental characteristic of hadron colliders is the abundant production of jets, which then are studied to learn about hard QCD, the proton structure, or nonperturbative effects. In the following the latest results and developments from the LHC experiments on jet cross sections, event shapes, flavour and rapidity dependence, and cross section ratios are presented. The ratio of the inclusive 3-jet to the inclusive 2-jet event cross section is used for a first determination of the strong coupling constant at the TeV scale.Comment: On behalf of the ATLAS and CMS Collaborations, 4 pages, 3 figures, pdflatex, to be published in the Proceedings of the 48th Rencontres de Moriond "QCD and High Energy Interactions", La Thuile, Italy, March 9-16, 201

    QCD and Electroweak Physics at LHC

    Full text link
    First LHC data have been collected and collisions at a center-of-mass energy of 7 TeV are anticipated for the next months. The commissioning of the detectors and the re-establishment of the Standard Model in the new energy regime will be the main tasks for the experimental collaborations in the year to come. This report summarizes the measurement plans and performance expectations of the ATLAS and CMS experiments for a selected number of QCD and electroweak analyses with an emphasis on the early data taking phase. Some longer term prospects are pointed out.Comment: 10 pages, 14 figures; Contribution to the 9th International Symposium on Radiative Corrections (RADCOR 2009), October 25-30 2009, Ascona, Switzerlan

    QCD Physics Potential of CMS

    Get PDF
    In view of the approaching LHC operation the feasibility and accuracy of QCD measurements with the CMS experiment at the Large Hadron Collider (LHC) involving hadrons and jets are discussed. This summary is based on analyses performed at CMS for center-of-mass energies of 10 as well as 14 TeV assuming event numbers ranging from some days of data taking up to 100/pb of integrated luminosity with proton-proton collisions.Comment: Institut fuer Experimentelle Kernphysik, University of Karlsruhe, Germany. On behalf of the CMS Collaboration, in proceedings of "1st IPM Meeting on LHC Physics, Isfahan, Iran, 20.-24. April 2009". 10 pages, 16 figure

    Experimental Tests of QCD

    Full text link
    The first very successful LHC running period has been finished. At 7 TeV centre-of-mass energy about 5/fb of data have been collected and at 8 TeV even 20/fb. Many detailed analyses of these data are still going on. The latest measurements on photon, weak boson plus jet, and jet production are compared against the most recent theory predictions. They are complemented by new results reported by the experiments at the Tevatron and HERA colliders. Finally, several new determinations of the strong coupling constant from jet data are presented.Comment: On behalf of the ATLAS and CMS Collaborations, 8 pages, 8 figures, pdflatex, to be published in the Proceedings of the Rencontres du Vietnam, Inaugural Conference of ICISE on "Windows on the Universe", Quy Nhon, Vietnam, August 11-17, 201

    Studies of Quantum Chromodynamics at the LHC

    Full text link
    A successful description of hadron-hadron collision data demands a profound understanding of quantum chromodynamics. Inevitably, the complexity of strong-interaction phenomena requires the use of a large variety of theoretical techniques -- from perturbative cross-section calculations up to the modelling of exclusive hadronic final states. Together with the unprecedented precision of the data provided by the experiments in the first running period of the LHC, a solid foundation of hadron-hadron collision physics at the TeV scale could be established that allowed the discovery of the Higgs boson and that is vital for estimating the background in searches for new phenomena. This chapter on studies of quantum chromodynamics at the LHC is part of a recent book on the results of LHC Run 1 and presents the advances in theoretical methods side-by-side with related key measurements in an integrated approach.Comment: 49 pages, 24 figures, To appear in "The Large Hadron Collider -- Harvest of Run 1", Thomas Sch\"orner-Sadenius (ed.), Springer, 2015 (532 pages, 253 figures; ISBN 978-3-319-15001-7, for more details, see http://www.springer.com/de/book/9783319150000

    A determination of mc(mc) from HERA data using a matched heavy-flavor scheme

    Get PDF
    The charm quark mass is one of the fundamental parameters of the Standard Model Lagrangian. In this work we present a determination of the MSbar charm mass from a fit to the inclusive and charm HERA deep-inelastic structure function data. The analysis is performed within the xFitter framework, with structure functions computed in the FONLL general-mass scheme as implemented in APFEL. In the case of the FONLL-C scheme, we obtain mc(mc) = 1.335 +- 0.043(exp) +0.019 -0.000(param) +0.011 -0.008(mod) +0.033 -0.008(th) GeV. We also perform an analogous determination in the fixed-flavor-number scheme at next-to-leading order, finding mc(mc) = 1.318 +- 0.054(exp) +0.011 -0.010(param) +0.015 -0.019(mod) +0.045 -0.004(th) GeV, compatible with the FONLL-C value. Our results are consistent with previous determinations from DIS data as well as with the PDG world average.Comment: 37 pages, 12 figures, 3 table

    Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

    Full text link
    The impact of recent measurements of heavy-flavour production in deep inelastic epep scattering and in pppp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions xx of the proton momentum, down to x∌5×10−6x \sim 5 \times 10^{-6}. This kinematic range is currently not covered by other experimental data in perturbative QCD fits

    Determination of the strong coupling constant using inclusive jet cross section data from multiple experiments

    Get PDF
    Abstract Inclusive jet cross section measurements from the ATLAS, CDF, CMS, D0, H1, STAR, and ZEUS experiments are explored for determinations of the strong coupling constant αs(MZ)\alpha _{\text {s}} (M_{\text {Z}}) αs(MZ) . Various jet cross section data sets are reviewed, their consistency is examined, and the benefit of their simultaneous inclusion in the αs(MZ)\alpha _{\text {s}} (M_{\text {Z}}) αs(MZ) determination is demonstrated. Different methods for the statistical analysis of these data are compared and one method is proposed for a coherent treatment of all data sets. While the presented studies are based on next-to-leading order in perturbative quantum chromodynamics (pQCD), they lay the groundwork for determinations of αs(MZ)\alpha _{\text {s}} (M_{\text {Z}}) αs(MZ) at next-to-next-to-leading order

    Proceedings of the 4th bwHPC Symposium

    Get PDF
    The bwHPC Symposium 2017 took place on October 4th, 2017, Alte Aula, TĂŒbingen. It focused on the presentation of scientific computing projects as well as on the progress and the success stories of the bwHPC realization concept. The event offered a unique opportunity to engage in an active dialogue between scientific users, operators of bwHPC sites, and the bwHPC support team