463 research outputs found
Extending the Minlo method
We consider improving Powheg+Minlo simulations, so as to also render them NLO accurate in the description of observables receiving contributions from events with lower parton multiplicity than present in their underlying NLO calculation. On a conceptual level we follow the strategy of the so-called Minlo ′ programs. Whereas the existing Minlo ′ framework requires explicit analytic input from higher order resummation, here we derive an effective numerical approximation to these ingredients, by imposing unitarity. This offers a way of extending the Minlo ′ method to more complex processes, complementary to the known route which uses explicit computations of high-accuracy resummation inputs. Specifically, we have focused on Higgs-plus-two-jet production (Hjj) and related processes. We also consider how one can cover three units of multiplicity at NLO accuracy, i.e. we consider how the Hjj-Minlo simulation may yield NLO accuracy for inclusive H, Hj and Hjj quantities. We perform a feasibility study assessing the potential of these ideas
Drell-Yan, ZZ, W+W- production in SM & ADD model to NLO+PS accuracy at the LHC
In this paper, we present the next-to-leading order QCD corrections for
di-lepton, di-electroweak boson (ZZ, W+W-) production in both the SM and the
ADD model, matched to the HERWIG parton-shower using the aMC@NLO framework. A
selection of results at the 8 TeV LHC, which exhibits deviation from the SM as
a result of the large extra-dimension scenario are presented.Comment: 12 pages, 10 figures, search sensitivity for the 14 TeV LHC
discussed, version to appear in Eur. Phys. J.
A Drug Dosage Table is a Useful Tool to Facilitate Prescriptions of Antiretroviral Drugs for Children in Thailand.
Scaling up of antiretroviral treatment (ART) for children in countries like Thailand will require decentralization and management by non-specialist doctors. We describe (a) the formulation of a standardized drug dosage table to facilitate antiretroviral drug (ARV) prescriptions for children, (b) the acceptability of such a table among doctors and (c) the safety and efficacy of drug doses in the table. Acceptability was assessed using a questionnaire. Safety and efficacy were assessed on the basis of incidence of adverse effects and virological response to treatment, respectively. Of all doctors (n=18), 17 (94%) found that the table was practical to use, avoided miscalculations and made them more confident with prescriptions. Of 49 children prescribed ARVs, less than 5% had adverse side-effects. All ARV-naĂŻve children achieved undetectable viral loads within six months of ART. In our setting, a standardized drug dosage table provided a simple and reliable tool that facilitated ARV prescriptions for children
Eulerian modeling of inertial and diffusional aerosol deposition in bent pipes
This paper presents a sectional Eulerian aerosol model for size-dependent droplet deposition at walls of the domain, driven by both diffusion and inertia. The model is based on the internally mixed assumption and employs the formulation for compressible aerosols. It is validated in a bent pipe geometry against models and experimental and numerical data from literature. Good agreement is found in both the diffusion and inertial deposition regimes. To improve the overprediction of inertial deposition by a boundary treatment that adopts zero-gradient droplet wall velocity, we use a corrected wall velocity, based on an analytical solution of the droplet motion near the wall. In the bent pipe setting the corrected wall velocity is found to reduce the overprediction of deposition and is less sensitive to grid refinement. We also show that refining the computational mesh near the pipe wall improves the predicted deposition efficiency, significantly. Finally, we present a parameter study varying the Reynolds number and the bend curvature. The deposition efficiency curve is recorded for droplet diameters ranging from the nanometer scale to beyond the micrometer scale, which is a unique contribution of this paper. The complete size range is simulated in only one simulation, due to the sectional approach. In the diffusion-dominated regime an increase in Reynolds number leads to a gradual enhancement of deposition. In the inertial regime, where droplet drift dominates deposition, a much stronger dependence on the Reynolds number is found. The dependence of the deposition on the bend curvature is less pronounced. The results shown in this paper establish the role of Eulerian simulation in predicting deposition of aerosol droplets and are useful for understanding size-dependent aerosol deposition in other more complex confined geometries
Thread-Scalable Evaluation of Multi-Jet Observables
A leading-order, leading-color parton-level event generator is developed for
use on a multi-threaded GPU. Speed-up factors between 150 and 300 are obtained
compared to an unoptimized CPU-based implementation of the event generator. In
this first paper we study the feasibility of a GPU-based event generator with
an emphasis on the constraints imposed by the hardware. Some studies of Monte
Carlo convergence and accuracy are presented for PP -> 2,...,10 jet observables
using of the order of 1e11 events.Comment: 16 pages, 5 figures, 3 table
Photon Radiation with MadDipole
We present the automation of a subtraction method for photon radiation using
the dipole formalism within the MadGraph framework. The subtraction terms are
implemented both in dimensional regularization and mass regularization for
massless and massive cases and non-collinear-safe observables are accounted
for.Comment: 23 pages, 2 figures, minor additions, references added, version
published in JHE
NLO QCD corrections in Herwig++ with MC@NLO
We present the calculations necessary to obtain next-to-leading order QCD
precision with the Herwig++ event generator using the MC@NLO approach, and
implement them for all the processes that were previously available from
Fortran HERWIG with MC@NLO. We show a range of results comparing the two
implementations. With these calculations and recent developments in the
automatic generation of NLO matrix elements, it will be possible to obtain NLO
precision with Herwig++ for a much wider range of processesComment: 26 pages, 28 figure
Super AutoDipole
The publicly available package for an automated dipole subtraction,
AutoDipole, is extended to include the SUSY dipoles in the MSSM. All fields in
the SM and the MSSM are available. The code is checked against the analytical
expressions for a simple process. The extended package makes it possible to
compute the QCD NLO corrections to SUSY multi-parton processes like the stop
pair production plus jets at the LHC.Comment: 16 pages, 1 figure, v2: a few typos to match the published version in
Eur. Phys. J.
Dynamic Behavior in Piezoresponse Force Microscopy
Frequency dependent dynamic behavior in Piezoresponse Force Microscopy (PFM)
implemented on a beam-deflection atomic force microscope (AFM) is analyzed
using a combination of modeling and experimental measurements. The PFM signal
comprises contributions from local electrostatic forces acting on the tip,
distributed forces acting on the cantilever, and three components of the
electromechanical response vector. These interactions result in the bending and
torsion of the cantilever, detected as vertical and lateral PFM signals. The
relative magnitudes of these contributions depend on geometric parameters of
the system, the stiffness and frictional forces of tip-surface junction, and
operation frequencies. The dynamic signal formation mechanism in PFM is
analyzed and conditions for optimal PFM imaging are formulated. The
experimental approach for probing cantilever dynamics using frequency-bias
spectroscopy and deconvolution of electromechanical and electrostatic contrast
is implemented.Comment: 65 pages, 15 figures, high quality version available upon reques
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