The Experts below are selected from a list of 138210 Experts worldwide ranked by ideXlab platform
Giampiero Passarino - One of the best experts on this subject based on the ideXlab platform.
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algebraic Numerical Evaluation of feynman diagrams two loop self energies
Nuclear Physics, 2002Co-Authors: Giampiero Passarino, Sandro UcciratiAbstract:Abstract A recently proposed scheme for Numerical Evaluation of Feynman diagrams is extended to cover all two-loop two-point functions with arbitrary internal and external masses. The adopted algorithm is a modification of the one proposed by F.V. Tkachov and it is based on the so-called generalized Bernstein functional relation. On-shell derivatives of self-energies are also considered and their infrared properties analyzed to prove that the method which is aimed to a Numerical Evaluation of massive diagrams can handle the infrared problem within the scheme of dimensional regularization. Particular care is devoted to study the general massive diagrams around their leading and non-leading Landau singularities.
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an approach toward the Numerical Evaluation of multi loop feynman diagrams
Nuclear Physics, 2001Co-Authors: Giampiero PassarinoAbstract:Abstract A scheme for systematically achieving accurate Numerical Evaluation of multi-loop Feynman diagrams is developed. This shows the feasibility of a project aimed to produce a complete calculation for two-loop predictions in the Standard Model. As a first step an algorithm, proposed by F.V. Tkachov and based on the so-called generalized Bernstein functional relation, is applied to one-loop multi-leg diagrams with particular emphasis to the presence of infrared singularities, to the problem of tensorial reduction and to the classification of all singularities of a given diagram. Successively, the extension of the algorithm to two-loop diagrams is examined. The proposed solution consists in applying the functional relation to the one-loop sub-diagram which has the largest number of internal lines. In this way the integrand can be made smooth, a part from a factor which is a polynomial in x S , the vector of Feynman parameters needed for the complementary sub-diagram with the smallest number of internal lines. Since the procedure does not introduce new singularities one can distort the x S -integration hyper-contour into the complex hyper-plane, thus achieving Numerical stability. The algorithm is then modified to deal with Numerical Evaluation around normal thresholds. Concise and practical formulas are assembled and presented, Numerical results and comparisons with the available literature are shown and discussed for the so-called sunset topology.
G Heinrich - One of the best experts on this subject based on the ideXlab platform.
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pysecdec a toolbox for the Numerical Evaluation of multi scale integrals
Computer Physics Communications, 2018Co-Authors: S Borowka, G Heinrich, S P Jones, Matthias Kerner, Johannes Schlenk, S Jahn, T ZirkeAbstract:Abstract We present py SecDec , a new version of the program SecDec , which performs the factorization of dimensionally regulated poles in parametric integrals, and the subsequent Numerical Evaluation of the finite coefficients. The algebraic part of the program is now written in the form of python modules, which allow a very flexible usage. The optimization of the C++ code, generated using FORM , is improved, leading to a faster Numerical convergence. The new version also creates a library of the integrand functions, such that it can be linked to user-specific codes for the Evaluation of matrix elements in a way similar to analytic integral libraries. Program summary Program Title: pySecDec Program Files doi: http://dx.doi.org/10.17632/3y8bbz9c9v.1 Licensing provisions: GNU Public License v3 Programming language: python, FORM, C++ External routines/libraries: catch [1], gsl [2], numpy [3], sympy [4], Nauty [5], Cuba [6], FORM [7], Normaliz [8]. The program can also be used in a mode which does not require Normaliz. Journal reference of previous version: Comput. Phys. Commun. 196 (2015) 470–491. Nature of the problem: Extraction of ultraviolet and infrared singularities from parametric integrals appearing in higher order perturbative calculations in quantum field theory. Numerical integration in the presence of integrable singularities (e.g. kinematic thresholds). Solution method: Algebraic extraction of singularities within dimensional regularization using iterated sector decomposition. This leads to a Laurent series in the dimensional regularization parameter ϵ (and optionally other regulators), where the coefficients are finite integrals over the unit-hypercube. Those integrals are evaluated Numerically by Monte Carlo integration. The integrable singularities are handled by choosing a suitable integration contour in the complex plane, in an automated way. The parameter integrals forming the coefficients of the Laurent series in the regulator(s) are provided in the form of libraries which can be linked to the calculation of (multi-) loop amplitudes. Restrictions: Depending on the complexity of the problem, limited by memory and CPU time. References: [1] https://github.com/philsquared/Catch/ . [2] http://www.gnu.org/software/gsl/ . [3] http://www.numpy.org/ . [4] http://www.sympy.org/ . [5] http://pallini.di.uniroma1.it/ . [6] T. Hahn, “CUBA: A Library for multidimensional Numerical integration,” Comput. Phys. Commun. 168 (2005) 78 [hep-ph/0404043], http://www.feynarts.de/cuba/ . [7] J. Kuipers, T. Ueda and J. A. M. Vermaseren, “Code Optimization in FORM,” Comput. Phys. Commun. 189 (2015) 1 [arXiv:1310.7007], http://www.nikhef.nl/ form/ . [8] W. Bruns, B. Ichim, B. and T. Romer, C. Soger, “Normaliz. Algorithms for rational cones and affine monoids.” http://www.math.uos.de/normaliz/ .
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secdec 3 0 Numerical Evaluation of multi scale integrals beyond one loop
Computer Physics Communications, 2015Co-Authors: S Borowka, G Heinrich, S P Jones, Matthias Kerner, Johannes Schlenk, T ZirkeAbstract:Abstract SecDec is a program which can be used for the factorization of dimensionally regulated poles from parametric integrals, in particular multi-loop integrals, and the subsequent Numerical Evaluation of the finite coefficients. Here we present version 3.0 of the program, which has major improvements compared to version 2: it is faster, contains new decomposition strategies, an improved user interface and various other new features which extend the range of applicability. Program summary Program title: SecDec 3.0 Catalogue identifier: AEIR_v3_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEIR_v3_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 123828 No. of bytes in distributed program, including test data, etc.: 1651026 Distribution format: tar.gz Programming language: Wolfram Mathematica, perl, Fortran/C++. Computer: From a single PC to a cluster, depending on the problem. Operating system: Unix, Linux. RAM: Depending on the complexity of the problem Classification: 4.4, 5, 11.1. Catalogue identifier of previous version: AEIR_v2_1 Journal reference of previous version: Comput. Phys. Comm. 184(2013)2552 Does the new version supersede the previous version?: Yes Nature of problem: Extraction of ultraviolet and infrared singularities from parametric integrals appearing in higher order perturbative calculations in gauge theories. Numerical integration in the presence of integrable singularities (e.g. kinematic thresholds). Solution method: Algebraic extraction of singularities within dimensional regularization using iterated sector decomposition. This leads to a Laurent series in the dimensional regularization parameter, where the coefficients are finite integrals over the unit-hypercube. Those integrals are evaluated Numerically by Monte Carlo integration. The integrable singularities are handled by choosing a suitable integration contour in the complex plane, in an automated way. Reasons for new version: • Improved user interface. • Additional new decomposition strategies. • Usage on a cluster is much improved. • Speed-up in Numerical Evaluation times. • Various new features (please see below). Summary of revisions: • Implementation of two new decompositions strategies based on a geometric algorithm. • Scans over large ranges of parameters are facilitated. • Linear propagators can be treated. • Propagators with negative indices are possible. • Interface to reduction programs like Reduze, Fire, LiteRed facilitated. • Option to use Numerical integrator from Mathematica. • Using CQUAD for 1-dimensional integrals to improve speed of Numerical Evaluations. • Option to include epsilon-dependent dummy functions. Restrictions: Depending on the complexity of the problem, limited by memory and CPU time. Running time: Between a few seconds and several hours, depending on the complexity of the problem.
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Numerical Evaluation of multi loop integrals for arbitrary kinematics with secdec 2 0
Computer Physics Communications, 2013Co-Authors: S Borowka, Jonathon Carter, G HeinrichAbstract:We present the program SecDec 2.0, which contains various new features. First, it allows the Numerical Evaluation of multi-loop integrals with no restriction on the kinematics. Dimensionally regulated ultraviolet and infrared singularities are isolated via sector decomposition, while threshold singularities are handled by a deformation of the integration contour in the complex plane. As an application, we present Numerical results for various massive two-loop four-point diagrams. SecDec 2.0 also contains new useful features for the calculation of more general parameter integrals, related for example to phase space integrals.
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Numerical Evaluation of multi loop integrals by sector decomposition
Nuclear Physics, 2004Co-Authors: T Binoth, G HeinrichAbstract:Abstract In a recent paper [Nucl. Phys. B 585 (2000) 741] we have presented an automated subtraction method for divergent multi-loop/leg integrals in dimensional regularisation which allows for their Numerical Evaluation, and applied it to diagrams with massless internal lines. Here we show how to extend this algorithm to Feynman diagrams with massive propagators and arbitrary propagator powers. As applications, we present Numerical results for the master 2-loop 4-point topologies with massive internal lines occurring in Bhabha scattering at two loops, and for the master integrals of planar and non-planar massless double box graphs with two off-shell legs. We also evaluate Numerically some two-point functions up to 5 loops relevant for beta-function calculations, and a 3-loop 4-point function, the massless on-shell planar triple box. Whereas the 4-point functions are evaluated in non-physical kinematic regions, the results for the propagator functions are valid for arbitrary kinematics.
Jocelyn Wittstein - One of the best experts on this subject based on the ideXlab platform.
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correlation of single assessment Numerical Evaluation score for sport and activities of daily living to modified harris hip score and hip outcome score in patients undergoing arthroscopic hip surgery
American Journal of Sports Medicine, 2019Co-Authors: Melissa Scribani, Tally Lassiter, Jocelyn WittsteinAbstract:Background:The Single Assessment Numerical Evaluation (SANE) is a single-question outcome score that has been shown to be a reliable measure of outcomes for shoulder and knee injuries but has not b...
Jason P Fine - One of the best experts on this subject based on the ideXlab platform.
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Numerical Evaluation of spray position for improved nasal drug delivery
arXiv: Medical Physics, 2019Co-Authors: Saikat Basu, Landon T Holbrook, Kathryn Kudlaty, Olulade O Fasanmade, Alyssa Burke, Benjamin Langworthy, Zainab Farzal, Mohammed Mamdani, William D Bennett, Jason P FineAbstract:Topical intra-nasal sprays are amongst the most commonly prescribed therapeutic options for sinonasal diseases in humans. However, inconsistency and ambiguity in instructions show a lack of definitive knowledge on best spray use techniques. In this study, we have identified a new usage strategy for nasal sprays available over-the-counter, that registers an average 8-fold improvement in topical delivery of drugs at diseased sites, when compared to prevalent spray techniques. The protocol involves re-orienting the spray axis to harness inertial motion of particulates and has been developed using computational fluid dynamics simulations of respiratory airflow and droplet transport in medical imaging-based digital models. Simulated dose in representative models is validated through in vitro spray measurements in 3D-printed anatomic replicas using the gamma scintigraphy technique. This work breaks new ground in proposing an alternative user-friendly strategy that can significantly enhance topical delivery inside human nose. While these findings can eventually translate into personalized spray usage instructions and hence merit a change in nasal standard-of-care, this study also demonstrates how relatively simple engineering analysis tools can revolutionize everyday healthcare.
Melissa Scribani - One of the best experts on this subject based on the ideXlab platform.
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correlation of single assessment Numerical Evaluation score for sport and activities of daily living to modified harris hip score and hip outcome score in patients undergoing arthroscopic hip surgery
American Journal of Sports Medicine, 2019Co-Authors: Melissa Scribani, Tally Lassiter, Jocelyn WittsteinAbstract:Background:The Single Assessment Numerical Evaluation (SANE) is a single-question outcome score that has been shown to be a reliable measure of outcomes for shoulder and knee injuries but has not b...
