61 research outputs found
Neural network determination of the non-singlet quark distribution
We summarize the main features of our approach to parton fitting, and we show
a preliminary result for the non-singlet structure function. When comparing our
result to other PDF sets, we find a better description of large x data and
larger error bands in the extrapolation regions.Comment: 4 pages, 1 eps figure. Presented at the XIV International Workshop on
Deep Inelastic Scattering (DIS2006), Tsukuba, Japan, 20-24 April 200
Quantum Isometries of the finite noncommutative geometry of the Standard Model
We compute the quantum isometry group of the finite noncommutative geometry F
describing the internal degrees of freedom in the Standard Model of particle
physics. We show that this provides genuine quantum symmetries of the spectral
triple corresponding to M x F where M is a compact spin manifold. We also prove
that the bosonic and fermionic part of the spectral action are preserved by
these symmetries.Comment: 29 pages, no figures v3: minor change
Expiratory airflow in late adolescence and early adulthood in individuals born very preterm or with very low birthweight compared with controls born at term or with normal birthweight : a meta-analysis of individual participant data
Background Maximal expiratory airflow peaks early in the third decade of life, then gradually declines with age. The pattern of airflow through adulthood for individuals born very preterm (at 2499 g) or at term. Methods We did a meta-analysis of individual participant data from cohort studies, mostly from the pre-surfactant era. Studies were identified through the Adults born Preterm International Collaboration and by searching PubMed and Embase (search date May 25, 2016). Studies were eligible if they reported on expiratory flow rates beyond 16 years of age in individuals born very preterm or with very low birthweight, as well as controls born at term or with normal birthweight. Studies with highly selected cohorts (eg, only participants with bronchopulmonary dysplasia) or in which few participants were born very preterm or with very low birthweight were excluded. De-identified individual participant data from each cohort were provided by the holders of the original data to a central site, where all the data were pooled into one data file. Any data inconsistencies were resolved by discussion with the individual sites concerned. Individual participant data on expiratory flow variables (FEV1, forced vital capacity [FVC], FEV1/FVC ratio, and forced expiratory flow at 25-75% of FVC [FEF25-75%]) were converted to Z scores and analysed with use of generalised linear mixed models in a one-step approach. Findings Of the 381 studies identified, 11 studies, comprising a total of 935 participants born very preterm or with very low birthweight and 722 controls, were eligible and included in the analysis. Mean age at testing was 21 years (SD 3.4; range 16-33). Mean Z scores were close to zero (as expected) in the control group, but were reduced in the very preterm or very low birthweight group for FEV1 (-0.06 [SD 1.03] vs -0.81 [1.33], mean difference -0.78 [95% CI -0.96 to -0.61], p Interpretation Individuals born very preterm or with very low birthweight are at risk of not reaching their full airway growth potential in adolescence and early adulthood, suggesting an increased risk of chronic obstructive pulmonary disease in later adulthood. Copyright (C) 2019 Elsevier Ltd. All rights reserved.Peer reviewe
Resonance capture cross section of 207Pb
The radiative neutron capture cross section of 207Pb has been measured at the
CERN neutron time of flight installation n_TOF using the pulse height weighting
technique in the resolved energy region. The measurement has been performed
with an optimized setup of two C6D6 scintillation detectors, which allowed us
to reduce scattered neutron backgrounds down to a negligible level. Resonance
parameters and radiative kernels have been determined for 16 resonances by
means of an R-matrix analysis in the neutron energy range from 3 keV to 320
keV. Good agreement with previous measurements was found at low neutron
energies, whereas substantial discrepancies appear beyond 45 keV. With the
present results, we obtain an s-process contribution of 77(8)% to the solar
abundance of 207Pb. This corresponds to an r-process component of 23(8)%, which
is important for deriving the U/Th ages of metal poor halo stars.Comment: 7 pages, 3 figures, to be published in Phys. Rev.
First Observation of B -> D(*) rho', rho' -> omega pi-
We report on the observation of B-> D(*) pi+ pi- pi- pi^o decays. The
branching ratios for D*+ and D*o are (1.72+/-0.14+/-0.24)% and
(1.80+/-0.24+/-0.27)%, respectively. Each final state has a D* omega pi-
component, with branching ratios (0.29+/-0.03+/-0.04)% and
(0.45+/-0.10+/-0.07)% for the D*+ and D*o modes, respectively. We also observe
B -> D omega pi- decays. The branching ratios for D+ and Do are
(0.28+/-0.05+/-0.04)% and (0.41+/-0.07+/-0.06)%, respectively. A spin parity
analysis of the D omega pi- final state prefers a wide 1^- resonance. A fit to
the omega pi- mass spectrum finds a central mass of (1349+/-25^{+10}_{-5}) MeV
and width of (547+/-86^{+46}_{-45}) MeV. We identify this object as the
rho(1450) or the \rho'.Comment: 42 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, To Appear in PR
Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter
Azimuthal angle \Delta\phi correlations are presented for charged hadrons
from dijets for 0.4 < p_T < 10 GeV/c in Au+Au collisions at sqrt(s_NN) = 200
GeV. With increasing p_T, the away-side distribution evolves from a broad to a
concave shape, then to a convex shape. Comparisons to p+p data suggest that the
away-side can be divided into a partially suppressed "head" region centered at
Delta\phi ~ \pi, and an enhanced "shoulder" region centered at Delta\phi ~ \pi
+/- 1.1. The p_T spectrum for the "head" region softens toward central
collisions, consistent with the onset of jet quenching. The spectral slope for
the "shoulder" region is independent of centrality and trigger p_T, which
offers constraints on energy transport mechanisms and suggests that the
"shoulder" region contains the medium response to energetic jets.Comment: 420 authors from 58 institutions, 6 pages, 4 figures. Submitted to
Physical Review Letters. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be) publicly
available at http://www.phenix.bnl.gov/papers.htm
Het Bestuursverbod bij de Commanditaire Vennootschap
Het onderwerp van dit onderzoek is de in art. 20 lid 2 WvK opgenomen regel
die het de commanditaire vennoot verbiedt de commanditaire vennootschap
waarin hij deelneemt te besturen. Teneinde dit onderwerp enig reliëf te geven
zal ik eerst in 1.1.2 in vogelvlucht ingaan op de specifieke kenmerken van de
commanditaire vennootschap en de plaats die zij inneemt in het systeem van het
Nederlandse vennootschapsrecht. Daarna zal ik in 1.1.3 aandacht besteden aan
de doeleinden waarvoor de commanditaire vennootschap in de rechtspraktijk
wordt ingezet. In 1.1.4 bespreek ik de bezwaren die in de huidige wettelijke
regeling aan deze rechtsvorm zijn verbonden. Dat leidt tot een formulering van
de onderzoeksvraag in 1.1.5 en een beschrijving van het belang van het
onderzoek in 1.1.6. Als laatste bespreek ik in 1.1.7 het theoretisch kader van
waaruit dit onderzoek is gedaan
Evidence of the purely leptonic decay B- -> tau(-)(v)over-bar(tau)
We present the first evidence of the decay B-->tau(-)nu(tau), using 414 fb(-1) of data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B-->tau(-)nu(tau))=(1.79(-0.49)(+0.56)(stat)(-0.51)(+0.46)(syst))x10(-4). This implies that f(B)=0.229(-0.031)(+0.036)(stat)(-0.037)(+0.034)(syst) GeV and is the first direct measurement of this quantity
Observation of b -> d gamma and determination of vertical bar V-td/V-ts vertical bar
We report the observation of the flavor-changing neutral current process b -> d gamma using a sample of 386 x 10(6) B meson pairs accumulated by the Belle detector at the KEKB e(+)e(-) collider. We measure branching fractions for the exclusive modes B- -> rho(-)gamma, (B) over bar (0) -> rho(0)gamma, and (B) over bar (0) -> omega gamma. Assuming that these three modes are related by isospin, we find B((B) over bar -> (rho, omega)gamma) = (1.32(-0.31)(+0.34)(stat)(-0.09)(+0.10)(syst)) x 10(-6) with a significance of 5.1 sigma. This result is used to determine the ratio of Cabibbo-Kobayashi-Maskawa matrix elements vertical bar V-td/V-ts vertical bar to be 0.199(-0.025)(+0.026)(exp)(-0.015)(+0.018)(theor)
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