2,404 research outputs found
On free energy of 2-d black hole in bosonic string theory
Trying to interpret recent matrix model results (hep-th/0101011) we discuss
computation of classical free energy of exact dilatonic 2-d black hole from the
effective action of string theory. The euclidean space-time action evaluated on
the black hole background is divergent due to linear dilaton vacuum
contribution, and its finite part depends on a subtraction procedure. The
thermodynamic approach based on subtracting the vacuum contribution for fixed
values of temperature and dilaton charge at the "wall" gives (as in the
leading-order black hole case) S= M/T for the entropy and zero value for the
free energy F. We suggest that in order to establish a correspondence with a
non-vanishing matrix model result for F one may need an alternative
reparametrization-invariant subtraction procedure using analogy with
non-critical string theory (i.e. replacing the spatial coordinate by the
dilaton field). The subtraction of the dilaton divergence then produces a
finite value for the free energy. We also propose a microscopic estimate for
the entropy and energy of the black hole based on the contribution of
non-singlet states of the matrix model.Comment: 25 pages, lanlma
Renormalization Group Improved Radiative Corrections to the Supersymmetric Higgs Boson Masses
The one-loop radiative corrections to the Higgs boson potential in the MSSM,
originating from the top quark and squark loops, are summed in the leading log
approximation using the renormalization group. The RG improved effective
potential is minimized and the corrections to the CP-odd and CP-even Higgs
boson masses are calculated. The resulting masses exhibit smoother top mass
dependence than those calculated without RG summation. We have also found that
for preferable values of the top mass the light Higgs mass does not exceed 100
GeV.Comment: 10 PAGES, 1 FIGURE ENCLOSED, LATE
IS (Low Energy) SUSY STILL ALIVE?
Supersymmetry, a new symmetry that relates bosons and fermions in particle
physics, still escapes observation. Search for supersymmetry is one of the main
aims of the Large Hadron Collider. The other possible manifestation of
supersymmetry is the Dark Matter in the Universe. The present lectures contain
a brief introduction to supersymmetry in particle physics. The main notions of
supersymmetry are introduced. The supersymmetric extension of the Standard
Model -- the Minimal Supersymmetric Standard Model -- is considered in more
detail. Phenomenological features of the Minimal Supersymmetric Standard Model
as well as possible experimental signatures of supersymmetry at the Large
Hadron Collider are described. The present limits on supersymmetric particles
are presented and the allowed region of parameter space of the MSSM is shown.Comment: 59 pages, 35 figures, PDFLatex, Lectures at the European School of
High-Energy Physics, June 2012, Anjou, Franc
Two-logarithm matrix model with an external field
We investigate the two-logarithm matrix model with the potential
related to an exactly solvable
Kazakov-Migdal model. In the proper normalization, using Virasoro constraints,
we prove the equivalence of this model and the Kontsevich-Penner matrix model
and construct the 1/N-expansion solution of this model.Comment: 15pp., LaTeX, no figures, reference adde
Determination of the observation conditions of celestial bodies with the aid of the DISPO system
The interactive system for determining the observation conditions of celestial bodies is described. A system of programs was created containing a part of the DISPO Display Interative System of Orbit Planning. The system was used for calculating the observatiion characteristics of Halley's comet during its approach to Earth in 1985-86
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