1,521 research outputs found
Renormalization Properties of Softly Broken SUSY Gauge Theories
In the present review we show that renormalizations in a softly broken SUSY
gauge theory are not independent but directly follow from those of an unbroken
or rigid theory. This is a consequence of a treatment of a softly broken theory
as a rigid one in external spurion superfield. This enables one to get the
singular part of effective action in a broken theory from a rigid one by a
simple modification of the couplings. Substituting the modified couplings into
renormalization constants, RG equations, solutions to these equations,
approximate solutions, fixed points, etc., one can get corresponding relations
for the soft terms by a simple Taylor expansion over the Grassmannian
variables. Some examples including the MSSM in low and high regime,
SUSY GUTs and the N=2 Seiberg-Witten model are considered.Comment: LaTeX, 25pp, 2 eps figures. Talk at "Continuous Advances in QCD
2002/Arkadyfest
Beyond The Standard Model
The present lectures contain an introduction to possible new physics beyond
the Standard Model. Having in mind first of all accelerator experiments of the
nearest future we concentrate on supersymmetry, a new symmetry that relates
bosons and fermions, as the first target of experimental search. Since
supersymmetry is widely covered in the literature, we mostly consider novel
developments and applications to hadron colliders. We describe then the
so-called extra dimensional models in less detail and discuss their possible
manifestations.Comment: 52 pages, 51 eps figures, Lectures given at the European School on
High Energy Physics, May-June 2004, Sant Feliu de Guixols, Spai
Renormalization Group Treatment of Nonrenormalizable Interactions
The structure of the UV divergencies in higher dimensional nonrenormalizable
theories is analysed. Based on renormalization operation and renormalization
group theory it is shown that even in this case the leading divergencies
(asymptotics) are governed by the one-loop diagrams the number of which,
however, is infinite. Explicit expression for the one-loop counter term in an
arbitrary D-dimensional quantum field theory without derivatives is suggested.
This allows one to sum up the leading asymptotics which are independent of the
arbitrariness in subtraction of higher order operators. Diagrammatic
calculations in a number of scalar models in higher loops are performed to be
in agreement with the above statements. These results do not support the idea
of the na\"ive power-law running of couplings in nonrenormalizable theories and
fail (with one exception) to reveal any simple closed formula for the leading
terms.Comment: LaTex, 11 page
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