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M. Tentyukov

Publications and source records attributed to M. Tentyukov.

At least 19 recordsLinked to original sources
arXiv2010

Parallel versions of the symbolic manipulation system FORM

The symbolic manipulation program FORM is specialized to handle very large algebraic expressions. Some specific features of its internal structure make FORM very well suited for parallelization. We have now two parallel versions of FORM, one is based on POSIX threads and is optimal for modern multicore computers while another one uses MPI and can be used to parallelize FORM on clusters and Massive Parallel Processing systems. Most existing FORM programs will be able to take advantage of the parallel execution without the need for modifications.

hep-ph↗
arXiv2010

Applications of FIESTA

Sector decomposition in its practical aspect is a constructive method used to evaluate Feynman integrals numerically. We present a new program performing the sector decomposition and integrating the expression afterwards. The program can be also used in order to expand Feynman integrals automatically in limits of momenta and masses with the use of sector decompositions and Mellin--Barnes representations. The program is parallelizable on modern multicore computers and even on multiple computers. Also we demonstrate some new numerical results for four-loop massless propagator master integrals.

hep-ph↗
arXiv2009

FIESTA 2: parallelizeable multiloop numerical calculations

The program FIESTA has been completely rewritten. Now it can be used not only as a tool to evaluate Feynman integrals numerically, but also to expand Feynman integrals automatically in limits of momenta and masses with the use of sector decompositions and Mellin-Barnes representations. Other important improvements to the code are complete parallelization (even to multiple computers), high-precision arithmetics (allowing to calculate integrals which were undoable before), new integrators and Speer sectors as a strategy, the possibility to evaluate more general parametric integrals.

hep-ph↗
arXiv2007

The Multithreaded version of FORM

We present TFORM, the version of the symbolic manipulation system FORM that can make simultaneous use of several processors in a shared memory architecture. The implementation uses Posix threads, also called pthreads, and is therefore easily portable between various operating systems. Most existing FORM programs will be able to take advantage of the increased processing power, without the need for modifications. In some cases some minor additions may be needed. For a computer with two processors a typical improvement factor in the running time is 1.7 when compared to the traditional version of FORM. In the case of computers with 4 processors a typical improvement factor in the execution time is slightly above 3.

hep-ph↗
arXiv2006

ep-Finite Basis of Master Integrals for the Integration-By-Parts Method

It is shown that for every problem within dimensional regularization, using the Integration-By-Parts method, one is able to construct a set of master integrals such that each corresponding coefficient function is finite in the limit of dimension equal to four. We argue that the use of such a basis simplifies and stabilizes the numerical evaluation of the master integrals. As an example we explicitly construct the ep-finite basis for the set of all QED-like four-loop massive tadpoles. Using a semi-numerical approach based on Pade approximations we evaluate analytically the divergent and numerically the finite part of this set of master integrals. The calculations confirm the recent results of Schröder and Vuorinen. All the contributions found there by fitting the high precision numerical results have been confirmed by direct analytical calculation without using any numerical input.

hep-ph↗
arXiv2005

Sophisticated momenta mapping with DIANA

Details of recent developments of the Feynman diagram analyzer DIANA (DIagram ANAlyser) are presented. Apart from some discussion about QGRAF and new plotting features, we concentrate on a new sophisticated mechanism of momenta mapping.

hep-ph↗
arXiv2005

ParFORM: recent development

We report on the status of our project of parallelization of the symbolic manipulation program FORM. We have now parallel versions of FORM running on Cluster- or SMP-architectures. These versions can be used to run arbitrary FORM programs in parallel.

cs.SC↗
arXiv2004

ParFORM: Parallel Version of the Symbolic Manipulation Program FORM

After an introduction to the sequential version of FORM and the mechanisms behind, we report on the status of our project of parallelization. We have now a parallel version of FORM running on Cluster- and SMP-architectures. This version can be used to run arbitrary FORM programs in parallel.

cs.SC↗
arXiv2003

Parallel Computation of Feynman diagrams with DIANA

Co-operation of the Feynman DIagram ANAlyzer (DIANA) with the underlying operational system (UNIX) is presented. We discuss operators to run external commands and a recent development of parallel processing facilities and an extension in the spirit of a component model.

hep-ph↗
arXiv2002

DIANA and selected applications

New developments concerning the extension of the Feynman diagram analyzer DIANA are presented. We discuss new graphics facilities, different approaches to automation of momenta distribution and parallel processing facilities. Furthermore applications to $t\bar t$ production and Bhabha scattering are shortly discussed.

hep-ph↗
arXiv2002

A Feynman diagram analyzer DIANA: recent development

New developments concerning the extension of the Feynman diagram analyzer DIANA are presented. We discuss new graphic facilities, application of DIANA to processes with Majorana fermions and different approaches to automation of momenta distribution.

hep-ph↗
arXiv2002

Diffraction and sigma_{gamma* p}

The empirical scaling law, wherein the total photoabsorption cross section depends on the single variable eta=(Q^2+m_0^2)/Lambda^2(W^2), provides empirical evidence for saturation in the sense of sigma_{gamma* p}(W^2,Q^2)/sigma_{gamma p}(W^2) --> 1 for W^2 --> infinity at fixed Q^2. The total photoabsorption cross section is related to elastic diffraction in terms of a sum rule. The excess of diffractive production over the elastic component is due to inelastic diffraction that contains the production of hadronic states of higher spins. Motivated by the diffractive mass spectrum, the generalized vector dominance/color dipole picture (GVD/CDP) is extended to successfully describe the DIS data in the full region of x=<0.1, all Q^2>=0, where the diffractive two-gluon-exchange mechanism dominates.

hep-ph↗
arXiv2002

The longitudinal structure function of the proton for small x

A comparison of the H1 data on the longitudinal structure function, $F_L$, at small $x$ with the predictions from the generalized vector dominance / color dipole picture (GVD/CDP) is presented. Using the set of parameters previously determined in the fits to the total cross section, $σ_{γ^* p}$, we find good agreement with the data for $F_L$. Scaling in $η= (Q^2 + m^2_0) / Λ^2 (W^2)$ is discussed in detail for the longitudinal and transverse photoabsorption cross sections.

hep-ph↗
arXiv2001

Scaling in $γ^* p$ total cross sections, saturation and the gluon density

Including the new HERA data, the $γ^* p$ total cross section is analysed in the generalized vector dominance/colour-dipole picture (GVD/CDP) that contains scaling in $η= (Q^2 + m^2_0) / Λ^2 (W^2)$, where $Λ^2 (W^2)$ is an increasing function of $W^2$. At any $Q^2$, for $W^2 \to \infty$, the cross sections for virtual and real photons become identical, $σ_{γ^* p} (W^2, Q^2) / σ_{γp} (W^2) \to 1$. The gluon density deduced from the colour-dipole cross section fulfills the leading order DGLAP relationship. Evolution à la DGLAP breaks down for $η\lsim 0.1$.

hep-ph↗
arXiv2001

The generalized vector dominance/colour-dipole picture of deep-inelastic scattering at low x

We give a detailed account of the recently formulated generalized vector dominance/colour-dipole picture (GVD/CDP) of deep-inelastic scattering at low $x\cong Q^2/W^2$, including photoproduction. The approach, based on $γ^*(q \bar q)$ transitions, $q \bar q$ propagation and diffractive $(q \bar q)p$ scattering via the generic structure of the two-gluon exchange, provides a unique and quantitatively successful theory for the $γ^* p$ total cross section, $σ_{γ^* p} (W^2,Q^2)$, at low $x$. The GVD/CDP is shown to imply the empirical low-$x$ scaling law, $σ_{γ^* p} (W^2,Q^2)=σ_{γ^* p} (η)$ with $η=(Q^2+m_0^2)/Λ^2(W^2)$, that was established by a model-independent analysis of the experimental data.

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