20,049 research outputs found
A Feynman Diagram Analyser DIANA
A C-program DIANA (DIagram ANAlyser) for the automatic Feynman diagram
evaluation is presented. It consists of two parts: the analyzer of diagrams and
the interpreter of a special text manipulating language. This language is used
to create a source code for analytical or numerical evaluations and to keep the
control of the process in general.Comment: 20 pages, latex, 3 eps figure
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.Comment: 2 pages, Latex using espcrc2.sty, 3 figures using 3 eps files.
Contribution to ACAT 2002, Moscow, Russia, June 24-28, 200
UV-finite scalar field theory with unitarity
In this paper we show how to define the UV completion of a scalar field
theory such that it is both UV-finite and perturbatively unitary. In the UV
completed theory, the propagator is an infinite sum of ordinary propagators. To
eliminate the UV divergences, we choose the coefficients and masses in the
propagator to satisfy certain algebraic relations, and define the infinite sums
involved in Feynman diagram calculation by analytic continuation. Unitarity can
be proved relatively easily by Cutkosky's rules. The theory is equivalent to
infinitely many particles with specific masses and interactions. We take the
theory as an example and demonstrate our idea through explicit Feynman
diagram computation.Comment: 14 pages, references adde
DIANA, a program for Feynman Diagram Evaluation
A C-program DIANA (DIagram ANAlyser) for the automatic Feynman diagram
evaluation is presented.Comment: LaTeX, 5 pages, no figures; talk given at 6th International Workshop
on Software Engineering, Artificial Intelligence, Neural Nets, Genetic
Algorithms, Symbolic Algebra, Automatic Calculation (AIHENP 99), Heraklion,
Crete, Greece, 12-16 April, 199
A steepest descent calculation of RNA pseudoknots
We enumerate possible topologies of pseudoknots in single-stranded RNA
molecules. We use a steepest-descent approximation in the large N matrix field
theory, and a Feynman diagram formalism to describe the resulting pseudoknot
structure
Systematic Implementation of Implicit Regularization for Multi-Loop Feynman Diagrams
Implicit Regularization (IReg) is a candidate to become an invariant
framework in momentum space to perform Feynman diagram calculations to
arbitrary loop order. In this work we present a systematic implementation of
our method that automatically displays the terms to be subtracted by
Bogoliubov's recursion formula. Therefore, we achieve a twofold objective: we
show that the IReg program respects unitarity, locality and Lorentz invariance
and we show that our method is consistent since we are able to display the
divergent content of a multi-loop amplitude in a well defined set of basic
divergent integrals in one loop momentum only which is the essence of IReg.
Moreover, we conjecture that momentum routing invariance in the loops, which
has been shown to be connected with gauge symmetry, is a fundamental symmetry
of any Feynman diagram in a renormalizable quantum field theory
A simple algorithm for automatic Feynman diagram generation
An algorithm for the automatic Feynman diagram (FD) generation is presented
in this paper. The algorithm starts directly from the definition formula of FD,
and is simple in concept and easy for coding. The symmetry factor for each FD
is naturally generated. It is expected to bring convenience for the researchers
who are studying new calculation techniques or making new calculation tools and
for the researchers who are studying effective field theory. A C-program made
from the algorithm is also presented, which is short, fast, yet very general
purpose: it receives arbitrary user defined model and arbitrary process as
input and generates FD's at any order.Comment: 11 pages, 2 figure
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