### Conveners

#### Computations in Theoretical Physics: Techniques and Methods: Monday

- Michal Malinsky (IFIC/CSIC and University of Valencia)

#### Computations in Theoretical Physics: Techniques and Methods: Monday

- Radja Boughezal (Argonne National Laboratory)

#### Computations in Theoretical Physics: Techniques and Methods: Tuesday

- Tord Riemann (DESY)

#### Computations in Theoretical Physics: Techniques and Methods: Tuesday

- Grigory Rubtsov (INR RAS)

#### Computations in Theoretical Physics: Techniques and Methods: Thursday

- Daniel Maitre (University of Durham (GB))

Thomas Hahn
(MPI f. Physik)

9/1/14, 2:00 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The Cuba library for multidimensional numerical integration has parallelization built in since Version 3. This presentation introduces Version 4 with extended facilities for distributed computation, including support for vectorized and GPU operation.

Stanislav Poslavsky
(I)

9/1/14, 2:25 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

Redberry is an open source computer algebra system with native support of tensorial expressions. It provides basic computer algebra tools (algebraic manipulations, substitutions, basic simplifications etc.) which are aware of specific features of indexed expressions: contractions of indices, permutational symmetries, multiple index types etc. The high energy physics package includes tools for...

Tord Riemann
(DESY)

9/1/14, 2:50 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

AMBRE is a Mathematica package for the evaluation of Feynman integrals with the aid of their Mellin-Barnes representations.
The new packages for
(i) a proper and efficient Mellin-Barnes presentation of non-planar topologies
and
(II) an automatic derivation of a subsequent representation by multiple sums are presented.
The latter one allows a linking of packages for automatic summation.

Michael Norbert Borinsky
(Humboldt-University Berlin)

9/1/14, 3:15 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

Two programs, feyngen and feyncop, are presented. feyngen is designed to generate high loop order Feynman graphs for Yang-Mills, QED and $\phi^k$ theories. feyncop can compute the coproduct of these graphs on the underlying Hopf algebra of Feynman graphs.
The programs can be validated by exploiting zero dimensional field theory combinatorics and identities on the Hopf algebra which follow...

Johann Felix von Soden-Fraunhofen
(Max Planck Institute for Physics)

9/1/14, 4:10 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

We present the version 2.0 of the program package GoSam, which
is a public program package to compute one-loop QCD and/or electroweak corrections
to multi-particle processes within and beyond the Standard Model.
The extended version of the Binoth-Les-Houches-Accord interface
to Monte Carlo programs is also implemented.
This allows a large flexibility regarding the combination of the...

juergen reuter
(DESY Hamburg, Germany)

9/1/14, 4:35 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

We describe the multi-purpose Monte-Carlo event generator WHIZARD
for the simulation of high-energy particle physics experiments. Besides
the presentation of the general features of the program like SM physics,
BSM physics, and QCD effects, special emphasis will be given to the support
of the most accurate simulation of the collider environments at hadron
colliders and especially at...

Karol Kampf
(Charles University (CZ))

9/1/14, 5:00 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The chiral SU(N) nonlinear sigma model represents one of the simplest case of effective field theory. For the last several decades it has played an extremely important role not only for the low energy phenomenology but also in many other areas of theoretical physics.
In this talk we will focus on the tree-level scattering amplitudes of the n-Goldstone bosons.
It will be shown that it can be...

Vitaly Yermolchyk
(Byelorussian State University (BY))

9/1/14, 5:25 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

We present the Monte Carlo event generator *LePaProGen* for lepton pair production at hadron colliders. LePaProGen focuses on the description of higher-order electroweak radiative corrections. The generator is implementing a new algorithm for the selection of the optimal variables for phase-space parametrization.

Gudrun Heinrich
(Max Planck Institute for Physics)

9/2/14, 2:00 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

SecDec is a program which can be used for the
evaluation of parametric integrals, in particular multi-loop integrals.
For a given set of propagators defining the graph,
the program automatically constructs
a Feynman parameter representation, extracts the singularities in the
dimensional regularisation parameter and produces a
Laurent series in this parameter, whose coefficients are...

David Heymes
(RWTH Aachen)

9/2/14, 2:25 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The main theoretical tool to provide precise predictions for scattering
cross sections of strongly interacting particles is perturbative QCD.
Starting at
next-to-leading order (NLO) the calculation suffers
from unphysical IR-divergences that cancel in the final result. At NLO
there exist general subtraction algorithms to treat these divergences
during a calculation. Since the LHC...

Prof.
Elise de Doncker
(Western Michigan University)

9/2/14, 2:50 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The paper will include numerical integration results
for Feynman loop diagrams through 3-loop such as
those covered by (Laporta, 2000). While Laporta
generated solutions by solving systems of difference
equations, the current methods are based on automatic
adaptive integration, using iterated integration
with programs from the QuadPack package, or multivariate
techniques from the ParInt...

Dr
Mikhail Kompaniets
(SPbSU)

9/2/14, 3:15 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

We present results of the six loop renormalization group calculations of the critical exponents in $O(n)$-symmetric $\phi^4$ theory in the framework of $\epsilon$-expansion (minimal subtraction scheme). Technical details of this calculations are discussed. Obtained results are compared with experimental data and with results of other theoretical approaches like $1/n$ expansion, renormalization...

Mr
Vladimir Bytev
(JINR)

9/2/14, 4:10 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The differential reduction algorithm which allow one to express generalized hypergeometric functions with arbitrary values of parameters
in terms of functions with fixed values of parameters differing from the original ones by integers is discussed in a context of evaluation of Feynman diagrams.
It is shown that the criterion of reducibility of multiloop Feynman integrals can be...

Andrey Pikelner
(Joint Inst. for Nuclear Research (RU))

9/2/14, 4:35 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

After three-loop beta functions for all Standard Model(SM) couplings in $\overline{MS}$ scheme become available, the last missing part for three-loop RGE analysis of SM become two-loop threshold corrections for low-energy input.
In this work we present full two-loop Electro-Weak corrections for top and bottom mass, it's Yukawa couplings, Higgs mass and it's self-coupling, and masses of W...

Gorazd Cvetic
(Santa Maria University)

9/2/14, 5:00 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

Perturbative QCD in the usual mass independent schemes gives us running coupling $a(Q^2) \equiv \alpha_s(Q^2)/\pi$ which has unphysical (Landau) singularities at low squared momenta $|Q^2| < 1 \ {\rm GeV}^2$ (where $Q^2 \equiv -q^2$). Such singularities do not reflect correctly the analytic (holomorphic) properties of spacelike observables ${\cal D}(Q^2)$ such as current correlators or...

Dr
Shinji Motoki
(High Energy Accelerator Research Organization)

9/2/14, 5:25 PM

Computing Technology for Physics Research

Oral

With the discovery of Higgs particle in CERN Large Hadron Collider,precision measurements are expected in future International Linear Collider to explore new physics beyond Standard Model. In tandem with experiments, an accurate theoretical prediction is required.To meet such a request, higher order correction in perturbative quantum field theory becomes more and more important and the method...

Dr
Andrei Kataev
(Institute for Nuclear Research of the Academy of Sciences of Russia)

9/4/14, 2:00 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The brief review of the modern developments of the studied by Grunberg ,Kataev, Chyla, Mikhailov , Brodsky, Wu , Mojaza and others
generalized Brodsky-Lepage-McKenzie approach,
for fixinx the sclaes in mutiloop
corrections to the renormalization-group invariant observable quantities in QCD are presented. The special attention is paid
to the procedure of splitting the perturbative...

Jakub Vícha on behalf of Pierre Auger Collaboration
(Institute of Physics AS CR)

9/4/14, 2:25 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

Cosmic rays of of ultra-high energy (above 10$^{18}$ eV) are very rare events and still of unknown origin. They provide a unique opportunity e.g. to study hadronic interactions at CMS energies more than one order of magnitude higher than it is achievable at LHC. The existence of the most energetic events (around $10^{20}$ eV) is theoretically very hard to
explain mostly because of the opacity...

David Walz
(RWTH Aachen)

9/4/14, 2:50 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

Solving the question of the origin of ultra-high energy cosmic rays
(UHECR) requires the development of detailed simulation tools in order
to interpret the experimental data and draw conclusions on the UHECR
universe. CRPropa is a public Monte Carlo code for the galactic and
extragalactic propagation of cosmic ray nuclei above $\sim 10^{17}$ eV, as well
as their photon and neutrino...

Grigory Rubtsov
(INR RAS)

9/4/14, 3:15 PM

Computations in Theoretical Physics: Techniques and Methods

Oral

The Telescope Array (TA) surface detector (SD) stations record the temporal development of the signal from the extensive air shower front which carries information about the type of the primary particle. We develop methods for studies of the primary mass composition of ultra-high-energy cosmic rays based on multivariate analysis (MVA). We propose to convert each observable into percentile rank...