Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Meditation Awareness Training for individuals with fibromyalgia syndrome: an interpretative phenomenological analysis of participants' experiences

Fibromyalgia syndrome (FMS) is a complex and poorly understood psychosomatic pain disorder. The illness has been the subject of controversy, both in terms of the alleged lack of interest and capability of the medical community to understand and support patients with FMS, and the burden that such individuals place upon economic and healthcare re- sources. Due to the lack of convincing data for the effectiveness of extant pharmacological and non-pharmacological FMS treatments, a recent direction in FMS research has been the empirical investigation of mindfulness and other meditation-based approaches. The present qualitative study explored whether following participation in a mindfulness-based intervention, patients with FMS report experiencing changes in (i) how they experience and relate to their illness and (ii) their attitudes towards societal participation, work and unemployment. Ten individuals with FMS were randomly selected from the intervention arm of a randomised controlled trial (RCT) evaluating the effectiveness of a mindfulness-based intervention known as Meditation Awareness Training (MAT) for the treatment of FMS. Transcripts of semi-structured interviews were analysed using Interpretative Phenomenological Analysis, a robust and rigorous qualitative methodology for analysing sub jective experiences. Five super-ordinate themes emerged from the dataset: (i) reservations about participating,(ii) improvements in psychosomatic well-being,(iii) spiritual growth,(iv) awareness of impermanence and (v) increased sense of citizenship. MAT was experienced as both an acceptable and accessible intervention by individuals with FMS, and participants reported experiencing improvements in psychosocial functioning as well as an increased sense of societal responsibility. MAT appears to have utility for treating FMS and for changing the attitudes of some individuals with FMS towards community engagement and societal contribution

The explanatory and predictive power of non two-stage-probability theories of decision making under ambiguity

Representing ambiguity in the laboratory using a Bingo Blower (which is transparent and not manipulable) and asking the subjects a series of allocation questions, we obtain data from which we can estimate by maximum likelihood methods (with explicit assumptions about the errors made by the subjects) a signicant subset of particular parameterisations of the empirically relevant models of behaviour unde ambiguity, and compare their relative explanatory and predictive abilities. Our results suggest that not all recent models of behaviour represent a major improvement in explanatory and predictive power, particularly the more theoretically sophisticated ones

Measurement of the transverse momentum distribution of [Z over γ*] bosons in proton-proton collisions at √s = 7 TeV with the ATLAS detector

A measurement of the [Z over γ*] transverse momentum (p[Z over T]) distribution in proton–proton collisions at √s = 7 TeV is presented using [Z over γ*] →e[superscript +]e[superscript −] and [Z over γ*] →μ[superscript +]μ[superscript −] decays collected with the ATLAS detector in data sets with integrated luminosities of 35 pb[superscript −1] and 40 pb[superscript −1], respectively. The normalized differential cross sections are measured separately for electron and muon decay channels as well as for their combination up to p[Z over T] of 350 GeV for invariant dilepton masses 66 GeV<m[subscript ℓℓ]<116 GeV. The measurement is compared to predictions of perturbative QCD and various event generators. The prediction of resummed QCD combined with fixed order perturbative QCD is found to be in good agreement with the data.United States. Dept. of EnergyNational Science Foundation (U.S.)Brookhaven National LaboratoryEuropean Organization for Nuclear Researc

Performance of the ATLAS Trigger System in 2010

Proton-proton collisions at sqrt{s} = 7 TeV and heavy ion collisions at sqrt{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 presente