205 research outputs found
Muon capture by 3He nuclei followed by proton and deuteron production
The paper describes an experiment aimed at studying muon capture by
nuclei in pure and mixtures at various densities. Energy distributions of
protons and deuterons produced via and are measured for the
energy intervals MeV and MeV, respectively. Muon capture
rates, and are obtained using two different analysis methods. The
least--squares methods gives , . The Bayes theorem
gives ,
. The experimental
differential capture rates, and , are compared with theoretical
calculations performed using the plane--wave impulse approximation (PWIA) with
the realistic NN interaction Bonn B potential. Extrapolation to the full energy
range yields total proton and deuteron capture rates in good agreement with
former results.Comment: 17 pages, 13 figures, accepted for publication in PR
Determination of alphaS from Hadronic Event Shapes in e+e- Annihilation at 192 < sqrt(s) < 208 GeV
Results are presented from a study of the structure of high energy hadronic
events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of
several event shape variables are compared to resummed O(alphaS^2) QCD
calculations. We determine the strong coupling constant at three average
centre-of-mass energies: 194.4, 200.2 and 206.2 GeV. These measurements,
combined with previous L3 measurements at lower energies, demonstrate the
running of alphaS as expected in QCD and yield alphaS(mZ) = 0.1227 +- 0.0012 +-
0.0058, where the first uncertainty is experimental and the second is
theoretical
Jet-jet and hadron-jet correlations in hadro- and electro-production
We discuss, in the framework of perturbative QCD at next to leading order,
two related observables which are usually considered to provide tests of the
BFKL dynamics : jet-jet correlations at Tevatron energies and forward
particle-jet correlations at HERA. In the first case we study the rapidity gap
dependence of the azimuthal correlations and find slightly too strong
correlations at large gap. In the second case we discuss the cross section as
well as the azimuthal correlations over a rapidity gap range of 5 units. We
find that the requirement of a forward particle imposes strong kinematical
constraints which distort the distributions, notably at small rapidity gaps. We
also show that the decorrelation is stronger in electroproduction than in
hadron-hadron collisions. Unfortunately no data are yet available for
comparison.Comment: LaTeX, 19 pages, 7 figures (9 figure files
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Identification of common genetic risk variants for autism spectrum disorder
Autism spectrum disorder (ASD) is a highly heritable and heterogeneous group of neurodevelopmental phenotypes diagnosed in more than 1% of children. Common genetic variants contribute substantially to ASD susceptibility, but to date no individual variants have been robustly associated with ASD. With a marked sample-size increase from a unique Danish population resource, we report a genome-wide association meta-analysis of 18,381 individuals with ASD and 27,969 controls that identified five genome-wide-significant loci. Leveraging GWAS results from three phenotypes with significantly overlapping genetic architectures (schizophrenia, major depression, and educational attainment), we identified seven additional loci shared with other traits at equally strict significance levels. Dissecting the polygenic architecture, we found both quantitative and qualitative polygenic heterogeneity across ASD subtypes. These results highlight biological insights, particularly relating to neuronal function and corticogenesis, and establish that GWAS performed at scale will be much more productive in the near term in ASD.Peer reviewe
Studies of Hadronic Event Structure in e+e- Annihilation from 30 GeV to 209 GeV with the L3 Detector
In this Report, QCD results obtained from a study of hadronic event structure
in high energy e^+e^- interactions with the L3 detector are presented. The
operation of the LEP collider at many different collision energies from 91 GeV
to 209 GeV offers a unique opportunity to test QCD by measuring the energy
dependence of different observables. The main results concern the measurement
of the strong coupling constant, \alpha_s, from hadronic event shapes and the
study of effects of soft gluon coherence through charged particle multiplicity
and momentum distributions.Comment: To appear in Physics Report
Meta-analysis of type 2 Diabetes in African Americans Consortium
Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR) = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe
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