466 research outputs found

    Helac-nlo

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    Based on the OPP technique and the HELAC framework, HELAC-1LOOP is a program that is capable of numerically evaluating QCD virtual corrections to scattering amplitudes. A detailed presentation of the algorithm is given, along with instructions to run the code and benchmark results. The program is part of the HELAC-NLO framework that allows for a complete evaluation of QCD NLO corrections.Comment: minor text revisions, version to appear in Comput.Phys.Commu

    Standard Model Higgs boson production in association with a top anti-top pair at NLO with parton showering

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    We present predictions for the production cross section of a Standard Model Higgs boson in association with a top-antitop pair at next-to-leading order accuracy using matrix elements obtained from the HELAC-Oneloop package. The NLO prediction was interfaced to the PYTHIA and HERWIG shower Monte Carlo programs with the help of POWHEG-Box, allowing for decays of massive particles, showering and hadronization, thus leading to final results at the hadron level.Comment: 14 pages, 9 figure

    Inhaler Devices for Delivery of LABA/LAMA Fixed-Dose Combinations in Patients with COPD

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    Published 13th March 2019. Issue Date June 2019. Funding. The preparation of this manuscript was funded by Novartis Pharma AG. No funding or sponsorship was recieved for the publication of this article. Medical Writing and Editorial Assistance The authors thank David Prefontaine, PhD and Rahul Lad, PhD (Novartis), and Praveen Kaul, PhD for providing medical writing and editorial support, which was funded by Novartis Pharma AG in accordance with Good Publication Practice (GPP3) guidelines.Peer reviewedPublisher PD

    Impact of the Conformational Variability of Oligopeptides on the Computational Prediction of Their CD Spectra

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    Although successful in the structural determination of ordered biomolecules, the spectroscopic investigation of oligopeptides in solution is hindered by their complex and rapidly changing conformational ensemble. The measured circular dichroism (CD) spectrum of an oligopeptide is an ensemble average over all microstates, severely limiting its interpretation, in contrast to ordered biomolecules. Spectral deconvolution methods to estimate the secondary structure contributions in the ensemble are still mostly based on databases of larger ordered proteins. Here, we establish how the interpretation of CD spectra of oligopeptides can be enhanced by the ability to compute the same observable from a set of atomic coordinates. Focusing on two representative oligopeptides featuring a known propensity toward an α-helical and ÎČ-hairpin motif, respectively, we compare and cross-validate the structural information coming from deconvolution of the experimental CD spectra, sequence-based de novo structure prediction, and molecular dynamics simulations based on enhanced sampling methods. We find that small conformational variations can give rise to significant changes in the CD signals. While for the simpler conformational landscape of the α-helical peptide de novo structure prediction can already give reasonabl

    GoSam: A program for automated one-loop Calculations

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    The program package GoSam is presented which aims at the automated calculation of one-loop amplitudes for multi-particle processes. The amplitudes are generated in terms of Feynman diagrams and can be reduced using either D-dimensional integrand-level decomposition or tensor reduction, or a combination of both. GoSam can be used to calculate one-loop corrections to both QCD and electroweak theory, and model files for theories Beyond the Standard Model can be linked as well. A standard interface to programs calculating real radiation is also included. The flexibility of the program is demonstrated by various examples.Comment: 10 pages, Talk given at the International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT), Uxbridge, London, September 201

    t \bar{t} W production and decay at NLO

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    We present results for the production of a top pair in association with a W-boson at next-to-leading order. We have implemented this process into the parton-level integrator MCFM including the decays of both the top quarks and the W-bosons with full spin correlations. Although the cross section for this process is small, it is a Standard Model source of same-sign lepton events that must be accounted for in many new physics searches. For a particular analysis of same-sign lepton events in which b-quarks are also present, we investigate the effect of the NLO corrections as a function of the signal region cuts.Comment: 10 pages, 7 figure

    Top Partner Discovery in the T→tZT\to tZ channel at the LHC

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    In this paper we study the discovery potential of the LHC run II for heavy vector-like top quarks in the decay channel to a top and a ZZ boson. Despite the usually smaller branching ratio compared to charged-current decays, this channel is rather clean and allows for a complete mass reconstruction of the heavy top. The latter is achieved in the leptonic decay channel of the ZZ boson and in the fully hadronic top channel using boosted jet and jet substructure techniques. To be as model-independent as possible, a simplified model approach with only two free parameters has been applied. The results are presented in terms of parameter space regions for 3σ3\sigma evidence or 5σ5\sigma discovery for such new states in that channel.Comment: 24 pages, 8 figures, version 2 updated to JHEP 01 (2015) 08

    Les Houches 2013: Physics at TeV Colliders: Standard Model Working Group Report

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    This Report summarizes the proceedings of the 2013 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt primarily with (1) the techniques for calculating standard model multi-leg NLO and NNLO QCD and NLO EW cross sections and (2) the comparison of those cross sections with LHC data from Run 1, and projections for future measurements in Run 2.Comment: Proceedings of the Standard Model Working Group of the 2013 Les Houches Workshop, Physics at TeV Colliders, Les houches 3-21 June 2013. 200 page
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