1,076 research outputs found
K-ary n-cube based off-chip communications architecture for high-speed packet processors
We present a detailed study of Higgs boson production in association with a single top quark at the LHC, at next-to-leading order accuracy in QCD. We consider total and differential cross sections, at the parton level as well as by matching short distance events to parton showers, for both t-channel and s-channel production. We provide predictions relevant for the LHC at 13 TeV together with a thorough evaluation of the residual uncertainties coming from scale variation, parton distributions, strong coupling constant and heavy quark masses. In addition, for t-channel production, we compare results as obtained in the 4-flavour and 5-flavour schemes, pinning down the most relevant differences between them. Finally, we study the sensitivity to a non-standard-model relative phase between the Higgs couplings to the top quark and to the weak bosons
tWH associated production at the LHC
We study Higgs boson production in association with a top quark and a
boson at the LHC. At NLO in QCD, interferes with and a
procedure to meaningfully separate the two processes needs to be employed. In
order to define production for both total rates and differential
distributions, we consider the diagram removal and diagram subtraction
techniques that have been previously proposed for treating intermediate
resonances at NLO, in particular in the context of production. These
techniques feature approximations that need to be carefully taken into account
when theoretical predictions are compared to experimental measurements. To this
aim, we first critically revisit the process, for which an extensive
literature exists and where an analogous interference with
production takes place. We then provide robust results for total and
differential cross sections for and at 13 TeV, also matching
short-distance events to a parton shower. We formulate a reliable prescription
to estimate the theoretical uncertainties, including those associated to the
very definition of the process at NLO. Finally, we study the sensitivity to a
non-Standard-Model relative phase between the Higgs couplings to the top quark
and to the boson in production.Comment: v3: expanded some discussions in the text, improved some plots
(results unchanged
Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction
At the LHC the CP properties of the top-quark Yukawa interaction can be
probed through Higgs production in gluon fusion or in association with top
quarks. We consider the possibility for both CP-even and CP-odd couplings to
the top quark to be present, and study CP-sensitive observables at
next-to-leading order (NLO) in QCD, including parton-shower effects. We show
that the inclusion of NLO corrections sizeably reduces the theoretical
uncertainties, and confirm that di-jet correlations in jet production
through gluon fusion and correlations of the top-quark decay products in production can provide sensitive probes of the CP nature of the Higgs
interactions.Comment: 18 pages, 9 figures, 12 tables; v2: references added, version to
appear in EPJ
Zinc(II)-methimazole complexes: synthesis and reactivity
The tetrahedral S-coordinated complex [Zn(MeImHS)(4)](ClO4)(2), synthesised from the reaction of [Zn(ClO4)(2)] with methimazole (1-methyl-3H-imidazole-2-thione, MeImHS), reacts with triethylamine to yield the homoleptic complex [Zn(MeImS)(2)] (MeImS = anion methimazole). ESI-MS and MAS C-13-NMR experiments supported MeImS acting as a (N, S)-chelating ligand. The DFT-optimised structure of [Zn(MeImS)(2)] is also reported and the main bond lengths compared to those of related Zn-methimazole complexes. The complex [Zn(MeImS)(2)] reacts under mild conditions with methyl iodide and separates the novel complex [Zn(MeImSMe)(2)I-2] (MeImSMe = S-methylmethimazole). X-ray diffraction analysis of the complex shows a ZnI2N2 core, with the methyl thioethers uncoordinated to zinc. Conversely, the reaction of [Zn( MeImS)(2)] with hydroiodic acid led to the formation of the complex [Zn(MeImHS)(2)I-2] having a ZnI2S2 core with the neutral methimazole units S-coordinating the metal centre. The Zn-coordinated methimazole can markedly modify the coordination environment when changing from its thione to thionate form and vice versa. The study of the interaction of the drug methimazole with the complex [Zn(MeIm)(4)](2+) (MeIm = 1-methylimidazole) - as a model for Zn-enzymes containing a N-4 donor set from histidine residues shows that methimazole displaces only one of the coordinated MeIm molecules; the formation constant of the mixed complex [Zn(MeIm)(3)(MeImHS)](2+) was determined
Piezoelectric Properties of SrBi4Ti4O15 Ferroelectric Ceramics
The dynamic piezoelectric response of SrBi4Ti4O15 ceramics with Aurivillius structure was investigated at high alternating stress, low frequencies (0.01 to 100 Hz), and temperatures from 20 to 200 °C. The piezoelectric nonlinearity, observed only at high pressures (>10 MPa) and elevated temperatures (>150 °C), is interpreted in terms of contributions from non-180° domain walls. At weak fields, the frequency dependence of the longitudinal piezoelectric coefficient was explained in terms of Maxwell-Wagner piezoelectric relaxation. The Maxwell-Wagner units are identified as colonies that consist of highly anisotropic grains which sinter together, and whose distribution in the ceramic is strongly dependent on sintering condition
Sol-gel synthesis of CaTiO3:Pr3+ red phosphors : tailoring the synthetic parameters for luminescent and afterglow applications
Two sol-gel synthetic routes for the preparation of CaTiO3: Pr3+ red emitting phosphors were compared, with the aim of producing nanostructured materials with tailored luminescence/afterglow properties. The effect of the synthetic parameters, such as the addition of a stabilizer and calcination temperature, on the structural, morphological, and optical properties was investigated. The desired perovskite phase was obtained at a calcination temperature of 800 degrees C or higher. Although the use of acetic acid as the chelating agent leads to micrometric particles with heterogeneous composition, the presence of hydroxypropylcellulose (HPC) results in smaller, less aggregated particles as well as in a high phase purity. At the highest HPC content, surface Ca-rich impurities were detected, although no segregated Ca-rich phases were detectable by X-ray powder diffraction analyses. Luminescence properties were found to be positively related to the phase purity of the oxide, with the highest quantum yields at temperatures equal to or higher than 1000 degrees C. On the contrary, persistent luminescence properties were highest at intermediate calcination temperatures and for samples synthesized with acetic acid. Overall, a notable role of oxygen vacancies resulting from local Ca excess was observed, acting as trap levels promoting longer relaxation pathways. Thanks to the small-sized particles and best steady-state luminescent properties due to a substantial decrease of lattice defects, the HPC synthesis is a promising strategy for light-emitting diode applications. On the other hand, the acetic acid synthesis promoted a higher defect density, which is required for an efficient yield of light emission in the long time range and is thus more suitable for afterglow applications
Emerg. Infect. Dis
The multidrug-resistant (MDR) Salmonella enterica serotype Newport strain that produces CMY-2 β-lactamase(Newport MDR-AmpC) was the source of sporadic cases and outbreaks in humans in France during 2000–2005. Because this strain was not detected in food animals, it was most likely introduced into France through imported food products
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