Measurement of the ratio of B+ and B0 meson lifetimes

The ratio of the B+ and B0 meson lifetimes was measured using data collected in 2002-2004 by the D0 experiment in Run II of the Fermilab Tevatron Collider. These mesons were reconstructed in B-->mu(+)nuD(*-)X decays, which are dominated by B0 and B-->mu(+)nuD 0X decays, which are dominated by B+. The ratio of lifetimes is measured to be tau(+)/tau(0)=1.080+/-0.016(stat)+/-0.014(syst).     

Search for anomalous heavy-flavor quark production in association with W bosons

We search for anomalous production of heavy-flavor quark jets in association with W bosons at the Fermilab Tevatron pp Collider in final states in which the heavy-flavor quark content is enhanced by requiring at least one tagged jet in an event. Jets are tagged using one algorithm based on semileptonic decays of b/c hadrons, and another on their lifetimes. We compare e+jets (164 pb(-1)) and mu+jets (145 pb(-1)) channels collected with the D0 detector at sqrt[s]=1.96 TeV to expectations from the standard model and set upper limits on anomalous production of such events.     

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).     

Jets and energy flow in photon-proton collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to data and QCD calculations. The comparisons show that theγp events can be consistently described by QCD models including — in addition to the primary hard scattering process — interactions between the two beam remnants. The differential jet cross sectionsdσ/dE _T^jet anddσ/dη ^jet are measured. Supported by the Bundesministerium für Forschung und Technologie, FRG under contract numbers 6AC17P, 6AC47P, 6DO571, 6HH17P, 6HH27I, 6HD17I, 6HD27I, 6KI17P, 6MP17I, and 6WT87P     

A model for dynamic chance constraints in hydro power reservoir management

In this paper, a model for (joint) dynamic chance constraints is proposed and applied to an optimization problem in water reservoir management. The model relies on discretization of the decision variables but keeps the probability distribution continuous. Our approach relies on calculating probabilities of rectangles which is particularly useful in the presence of independent random variables but works equally well in the case of correlated variables. Numerical results are provided for two and three stages.     

Using infrared thermography in order to compare laser and hybrid (laser+MIG) welding processes

In order to deepen the understanding of the differences between laser and laser-arc hybrid welding, comparisons were undertaken using thermography. The experiments were carried out for a T assembly of aluminium alloy plates. Modelling, based on the finite element method approach, was realized using IR temperature measurements and seam geometry. For a value of the power supply, depicted as a surface source in the hybrid case, agreement was found between simulated and measured temperatures. The arc power supply efficiency value is similar to the usually used value.     

Synthesis of adaptative and amphiphilic polymer model conetworks by versatile combination of ATRP,ROP, and “Click chemistry”

Well‐defined adaptative and amphiphilic polymer conetworks based on hydrophilic poly(N,N‐dimethylamino‐2‐ethyl methacrylate) (PDMAEMA) and hydrophobic poly(ε‐caprolactone) (PCL) have been prepared by combination of ATRP, ROP, and “Click chemistry.” Telechelic α,ω‐alkyne terminated PCL crosslinker was obtained by ring‐opening polymerization (ROP) of CL in THF at 80 °C initiated by 1,4‐butanediol and catalyzed by tin(II) bis 2‐ethyl hexanoate (Sn(Oct)₂), followed by the quantitative esterification of hydroxyl end‐groups by activated 4‐pentynoic acid. In parallel, an azido‐containing PDMAEMA‐based copolymer was obtained in a three‐step strategy involving primarily the copolymerization of DMAEMA with newly synthesized 2‐(2‐azidoethoxy)ethyl methacrylate (AEEMA) monomer. The latter was obtained by nucleophilic substitution of chloride atom from 2‐(2‐chloroethoxy)ethanol by an azide group followed by the esterification reaction of the hydroxyl group with methacrylic anhydride. The copolymerization was carried out in an equivolumic mixture of H₂O and isopropanol at r.t. and initiated by a ω‐bromoisobutyryl oligo PEO macroinitiator in the presence of various ligated copper(I)‐based catalysts. In a last step, both polymer precursors were chemically linked by the Huisgen‐1,3‐dipolar cycloaddition in anhydrous THF at r.t. using CuBr complexed by 2,2′‐bipyridine ligand as catalyst. Final material was characterized by the means of DSC and SEM, both attesting of a homogeneous distribution of the PCL crosslinkers and a highly porous structure in this new amphiphilic model conetworks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4997–5013, 2008