3,890 research outputs found
Measurement of the cross section for open b-quark production in two-photon interactions at LEP RID G-1279-2010
No full textInclusive b-quark production in two-photon collisions has been measured at LEP using an integrated luminosity of 698 pb(-1) collected by the ALEPH detector with root s between 130 and 209 GeV. The b quarks were identified using lifetime information. The cross section is found to be sigma(e(+)e -> e(+)e(-) bb(-)X) = (5.4 +/- 0.8(stat) +/- 0.8(syst)) pb, which is consistent with Next-to-Leading Order QCD
Measurement of Z-pair production in e+ e- collisions and constraints on anomalous neutral gauge couplings.
No full textThe ZZ production cross section is measured from a data sample corresponding to a total integrated luminosity of 452 pb−1, collected by the ALEPH experiment at LEP at centre-of-mass energies from 192 to 209 GeV. Individual cross sections, extracted at six centre-of-mass energies, are found to be in agreement with Standard Model calculations. The results are used to set limits on anomalous neutral gauge couplings
A study of the production cross-section in collisions at TeV using tau final states
No full textA measurement of the inclusive Z → ττ cross-section in pp collisions at TeX is presented based on a dataset of 1.0 fb−1 collected by the LHCb detector. Candidates for Z → τ τ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c 2, which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σ pp→Z→ττ = 71.4 ± 3.5 ± 2.8 ± 2.5 pb; the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z → τ τ to Z → μμ is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements
Test of colour reconnection models using three-jet events in hadronic Z decays
No full textHadronic Z decays into three jets are used to test QCD models of colour reconnection (CR). A sensitive quantity is the rate of gluon jets with a gap in the particle rapidity distribution and zero jet charge. Gluon jets are identified by either energy-ordering or by tagging two b-jets. The rates predicted by two string-based tunable CR models, one implemented in JETSET (the GAL model), the other in ARIADNE, are too high and disfavoured by the data, whereas the rates from the corresponding non-CR standard versions of these generators are too low. The data can be described by the GAL model assuming a small value for the R(0) parameter in the range 0.01-0.02
Deuteron and anti-deuteron production in e(+)e(-) collisions at the Z resonance RID C-6238-2011 RID G-1279-2010
No full textDeuteron and anti-deuteron production in Z decays has been observed in the ALEPH experiment at LER The production rate of anti-deuterons is measured to be (5.9 +/- 1.8 +/- 0.5) x 10(-6) per hadronic Z decay in the anti-deuteron momentum range from 0.62 to 1.03 GeV/c. The coalescence parameter B(2), which characterizes the likelihood of anti-deuteron production, is measured to be 0.0033 +/- 0.0013 GeV(2) in Z decays. These measurements indicate that the production of anti-deuterons is suppressed in e(+)e(-) collisions compared to that in pp and photoproduction collisions. (c) 2006 Elsevier B.V. All rights reserved
Poor quality drugs: grand challenges in high throughput detection, countrywide sampling, and forensics in developing countries.
No full textThroughout history, poor quality medicines have been a persistent problem, with periodical crises in the supply of antimicrobials, such as fake cinchona bark in the 1600s and fake quinine in the 1800s. Regrettably, this problem seems to have grown in the last decade, especially afflicting unsuspecting patients and those seeking medicines via on-line pharmacies. Here we discuss some of the challenges related to the fight against poor quality drugs, and counterfeits in particular, with an emphasis on the analytical tools available, their relative performance, and the necessary workflows needed for distinguishing between genuine, substandard, degraded and counterfeit medicines
Search for extra dimensions in diphoton events from proton–proton collisions at sqrt {s} = 7 TeV TeV in the ATLAS detector at the LHC
No full textContains fulltext :
111236.pdf (Author’s version preprint ) (Open Access
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