7,084 research outputs found
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 production and Bhabha scattering are
shortly discussed.Comment: Latex, 5 pages, 4 eps figures, uses included npb.sty, presented by at
RADCOR and Loops and Legs 2002 8-13 September 2002, in Kloster Banz, German
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
Calculation of Feynman diagrams with zero mass threshold from their small momentum expansion
A method of calculating Feynman diagrams from their small momentum expansion
[1] is extended to diagrams with zero mass thresholds. We start from the
asymptotic expansion in large masses [2] (applied to the case when all
are large compared to all momenta squared). Using dimensional regularization, a
finite result is obtained in terms of powers of logarithms (describing the
zero-threshold singularity) times power series in the momentum squared.
Surprisingly, these latter ones represent functions, which not only have the
expected physical `second threshold' but have a branchcut singularity as well
below threshold at a mirror position. These can be understood as
pseudothresholds corresponding to solutions of the Landau equations. In the
spacelike region the imaginary parts from the various contributions cancel. For
the two-loop examples with one mass , in the timelike region for we obtain approximations of high precision. This will be of
relevance in particular for the calculation of the decay in
the approximation.Comment: 17 pages with figures and tables, PostScript file gzip'ed and
uuencode
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.Comment: 4 pages, 4 Encapsulated postscript figures, LaTeX2e, uses espcrc2.sty
(included). Talk given at ACAT0
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.Comment: 23 pages, Latex using psfig, epsf and alltt, 3 figure
Exploring CP Violation through B Decays
The B-meson system provides many strategies to perform stringent tests of the
Standard-Model description of CP violation. In this brief review, we discuss
implications of the currently available B-factory data on the angles alpha,
beta and gamma of the unitarity triangle, emphasize the importance of Bs
studies at hadronic B experiments, and discuss new, theoretically clean
strategies to determine gamma.Comment: 22 pages, 4 figures, invited brief review for Modern Physics Letters
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
B -> pi pi, New Physics in B -> pi K and Implications for Rare K and B Decays
The measured B -> pi pi, pi K branching ratios exhibit puzzling patterns. We
point out that the B -> pi pi hierarchy can be nicely accommodated in the
Standard Model (SM) through non-factorizable hadronic interference effects,
whereas the B -> pi K system may indicate new physics (NP) in the electroweak
(EW) penguin sector. Using the B -> pi pi data and the SU(3) flavour symmetry,
we may fix the hadronic B -> pi K parameters, which allows us to show that any
currently observed feature of the B -> pi K system can be easily explained
through enhanced EW penguins with a large CP-violating NP phase. Restricting
ourselves to a specific scenario, where NP enters only through Z^0 penguins, we
derive links to rare K and B decays, where an enhancement of the K_L-> pi^0 nu
nu_bar rate by one order of magnitude, with BR(K_L -> pi^0 nu nu_bar) > BR(K^+
-> pi^+ nu nu_bar), BR(K_L -> pi^0 e^+ e^-)=O(10^{-10}), (\sin2\beta)_{pi nu
nu_bar} K* mu^+ mu^-,
are the most spectacular effects. We address also other rare K and B decays,
epsilon'/epsilon and B_d -> phi K_S.Comment: 6 pages, LaTeX, reference added and a few typos correced, to appear
in Physical Review Letter
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
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