18,016 research outputs found
A Proposal of a Renormalization Group Transformation for Lattice Field Theories
We propose a new Real Space Renormalization Group transformation useful for
Monte Carlo calculations in theories with global or local symmetries. From
relaxation arguments we define the block-spin transformation with two tunable
free parameters, adapted to the system's action. Varying them it is possible to
place the fixed point very close to the simulation point. We show how the
method works in a simple model with global symmetry: the three dimensional XY
model.Comment: 26 pages, uuencoded compressed postscript single file, 8 figures
include
SUSY Soft Breaking Terms from String Scenarios
The general SUSY soft breaking terms for a large class of phenomenologically
relevant string scenarios (symmetric orbifolds) are given. They show a certain
lack of universality, but not dangerous for flavor changing neutral currents.
To get more quantitative results a specific SUSY breaking mechanism has to be
considered, namely gaugino condensation in the hidden sector. Then, it turns
out that squark and slepton masses tend to be much larger than scalar masses
(), which probably is a quite general fact. Experimental
bounds and the requirement of a successful electroweak breaking without fine
tuning impose further restrictions on the soft breaking terms. As a consequence
the gluino and chargino masses should be quite close to their present
experimental limits, whereas squark and slepton masses should be much higher (>
1 TeV).Comment: (Talk presented at the SUSY-93 Conference, Boston, March 29 - April
2, 1993), 11 pages, CERN--TH.6922/9
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