13 research outputs found

    K-ary n-cube based off-chip communications architecture for high-speed packet processors

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    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

    Higgs characterisation at NLO in QCD: CP properties of the top-quark Yukawa interaction

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    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 H+2H+2 jet production through gluon fusion and correlations of the top-quark decay products in ttˉHt\bar tH 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

    tWH associated production at the LHC

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    We study Higgs boson production in association with a top quark and a WW boson at the LHC. At NLO in QCD, tWHtWH interferes with ttˉHt\bar t H and a procedure to meaningfully separate the two processes needs to be employed. In order to define tWHtWH 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 tWtW 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 tWtW process, for which an extensive literature exists and where an analogous interference with ttˉt \bar t production takes place. We then provide robust results for total and differential cross sections for tWtW and tWHtWH 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 WW boson in tWHtWH production.Comment: v3: expanded some discussions in the text, improved some plots (results unchanged

    Bismuth oxyhalides for NOx degradation under visible light: the role of the chloride precursor

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    ABSTRACT: Photocatalysis is a green technology for tackling water and air contamination. A valid alternative to the most exploited photocatalytic material, TiO2, is bismuth oxyhalides, which feature a wider bandgap energy range and use visible radiation to attain photoexcitation. Moreover, their layered structure favors the separation of photogenerated electron–hole pairs, with an enhancement in photocatalytic activity. Controlled doping of bismuth oxyhalides with metallic bismuth nanoparticles allows for further boosting of the performance of the material. In the present work, we synthesized Y%Bi-doped BiO(Cl0.875Br0.125) (Y = 0.85, 1, 2, 10) photocatalysts, using cetyltrimethylammonium bromide as the bromide source and varying the chloride source to assess the impact that both length and branching of the hydrocarbon chain might have on the framing and layering of the material. A change in the amount of the reducing agent NaBH4 allowed tuning of the percentage of metallic bismuth. After a thorough characterization (XRPD, SEM, TEM, UV-DRS, XPS), the photocatalytic activity of the catalysts was tested in the degradation of NOx under visible light, reaching a remarkable 53% conversion after 3 h of illumination for the material prepared using cetylpyridinium chloride

    PRENOLIN project. Results of the validation phase at sendai site

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    One of the objectives of the PRENOLIN project is the assessment of uncertainties associated with non-linear simulation of 1D site effects. An international benchmark is underway to test several numerical codes, including various non-linear soil constitutive models, to compute the non-linear seismic site response. The preliminary verification phase (i.e. comparison between numerical codes on simple, idealistic cases) is now followed by the validation phase, which compares predictions of such numerical estimations with actual strong motion data recorded from well-known sites. The benchmark presently involves 21 teams and 21 different non-linear computations. Extensive site characterization was performed at three sites of the Japanese KiK-net and PARI networks. This paper focuses on SENDAI site. The first results indicate that a careful analysis of the data for the lab measurement is required. The linear site response is overestimated while the non-linear effects are underestimated in the first iteration. According to these observations, a first set of recommendations for defining the non-linear soil parameters from lab measurements is proposed. PRENOLIN is part of two larger projects: SINAPS@, funded by the ANR (French National Research Agency) and SIGMA, funded by a consortium of nuclear operators (EDF, CEA, AREVA, ENL)

    Higgs boson interaction with the top quark : CP properties at the LHC

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    It is astonishing how the variety of Nature, from all the living species to oceans, mountains and stars, results from different rearrangements of the same few building blocks, the elementary particles. The standard model (SM) of particle physics has been incredibly effective so far in describing the interactions among our fundamental constituents, which ultimately determine significant properties of ourselves and our universe. The 2012 discovery of the Higgs boson at the LHC experiments has marked the completion of the SM picture, and the beginning of a new journey: the quest for new physics beyond the current paradigm. This quest can be pursued in many directions, including the search for deviations from the SM predictions in the interactions among the Higgs boson and the other elementary particles. In this thesis I address the interaction between the Higgs boson and the top quark, the two heaviest known elementary particles, which are at the centre of the LHC research. I promote predictions accurate at next-to-leading order (NLO) in perturbation theory for processes relevant to study this interaction at the LHC. I show how NLO accuracy is decisive in order to reduce systematic uncertainties in the theoretical computations, such as the scale dependence or the number of light quarks (flavour scheme). It is essential to control these uncertainties if we want to spot signs of new phenomena in deviations from the SM. I also discuss several observables sensitive to new physics that can be measured at the LHC. In particular, I focus on hypothetical CP-violating effects in the Higgs-top interaction, which could help to explain the imbalance between matter and antimatter observed in the universe.(SC - Sciences) -- UCL, 201

    Higgs production in association with a single top quark at the LHC

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    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

    Impact of parton distribution function and α

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    Bismuth Oxyhalides for NOx Degradation under Visible Light: The Role of the Chloride Precursor

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    Photocatalysis is a green technology for tackling water and air contamination. A valid alternative to the most exploited photocatalytic material, TiO2, is bismuth oxyhalides, which feature a wider bandgap energy range and use visible radiation to attain photoexcitation. Moreover, their layered structure favors the separation of photogenerated electron–hole pairs, with an enhancement in photocatalytic activity. Controlled doping of bismuth oxyhalides with metallic bismuth nanoparticles allows for further boosting of the performance of the material. In the present work, we synthesized Y%Bi-doped BiO(Cl0.875Br0.125) (Y = 0.85, 1, 2, 10) photocatalysts, using cetyltrimethylammonium bromide as the bromide source and varying the chloride source to assess the impact that both length and branching of the hydrocarbon chain might have on the framing and layering of the material. A change in the amount of the reducing agent NaBH4 allowed tuning of the percentage of metallic bismuth. After a thorough characterization (XRPD, SEM, TEM, UV-DRS, XPS), the photocatalytic activity of the catalysts was tested in the degradation of NOx under visible light, reaching a remarkable 53% conversion after 3 h of illumination for the material prepared using cetylpyridinium chloride
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