1,642 research outputs found
Nonextensive Quantum H-Theorem
A proof of the quantum -theorem taking into account nonextensive effects
on the quantum entropy is shown. The positiveness of the time variation
of combined with a duality transformation implies that the nonextensive
parameter lies in the interval [0,2]. It is also shown that the equilibrium
states are described by quantum -power law extensions of the Fermi-Dirac and
Bose-Einstein distributions. Such results reduce to the standard ones in the
extensive limit, thereby showing that the nonextensive entropic framework can
be harmonized with the quantum distributions contained in the quantum
statistics theory.Comment: 5 pages, LaTe
A Layman's guide to SUSY GUTs
The determination of the most straightforward evidence for the existence of
the Superworld requires a guide for non-experts (especially experimental
physicists) for them to make their own judgement on the value of such
predictions. For this purpose we review the most basic results of Super-Grand
unification in a simple and clear way. We focus the attention on two specific
models and their predictions. These two models represent an example of a direct
comparison between a traditional unified-theory and a string-inspired approach
to the solution of the many open problems of the Standard Model. We emphasize
that viable models must satisfy {\em all} available experimental constraints
and be as simple as theoretically possible. The two well defined supergravity
models, and , can be described in terms of only a few
parameters (five and three respectively) instead of the more than twenty needed
in the MSSM model, \ie, the Minimal Supersymmetric extension of the Standard
Model. A case of special interest is the strict no-scale
supergravity where all predictions depend on only one parameter (plus the
top-quark mass). A general consequence of these analyses is that supersymmetric
particles can be at the verge of discovery, lurking around the corner at
present and near future facilities. This review should help anyone distinguish
between well motivated predictions and predictions based on arbitrary choices
of parameters in undefined models.Comment: 25 pages, Latex, 11 figures (not included), CERN-TH.7077/93,
CTP-TAMU-65/93. A complete ps file (1.31MB) with embedded figures is
available by request from [email protected]
Hunting for the New Symmetries in Calabi-Yau Jungles
It was proposed that the Calabi-Yau geometry can be intrinsically connected
with some new symmetries, some new algebras. In order to do this it has been
analyzed the graphs constructed from K3-fibre CY_d (d \geq 3) reflexive
polyhedra. The graphs can be naturally get in the frames of Universal
Calabi-Yau algebra (UCYA) and may be decode by universal way with changing of
some restrictions on the generalized Cartan matrices associated with the Dynkin
diagrams that characterize affine Kac-Moody algebras. We propose that these new
Berger graphs can be directly connected with the generalizations of Lie and
Kac-Moody algebras.Comment: 29 pages, 15 figure
A new scenario for string unification
We present a new scenario for gauge coupling unification in flipped SU(5)
string models, which identifies the scale of SU(3) and SU(2)
unification with the empirical ~GeV scale, and the
scale of SU(5) and U(1) unification with the theoretical ~GeV string unification scale. The vacuum shift
necessary for the cancellation of the anomalous and an SU(4)
hidden sector with fractionally-charged particles, play a crucial role in the
dynamical determination of all intermediate mass scales in this scenario.Comment: 8 pages, LaTeX, 2 figures (uuencoded
Precision Electroweak Tests of the Minimal and Flipped SU(5) Supergravity Models
We explore the one-loop electroweak radiative corrections in the minimal
and the no-scale flipped supergravity models via explicit
calculation of vacuum polarization contributions to the
parameters. Experimentally, are obtained from a global fit
to the LEP observables, and measurements. We include -dependent
effects which have been neglected in most previous ``model-independent"
analyses of this type. These effects induce a large systematic negative shift
on for light chargino masses (m_{\chi^\pm_1}\lsim70\GeV).
In agreement with previous general arguments, we find that for increasingly
large sparticle masses, the heavy sector of both models rapidly decouples, \ie,
the values for quickly asymptote to the Standard Model
values with a {\it light} Higgs (m_{H_{SM}}\sim100\GeV). Specifically, at
present the CL upper limit on the top-quark mass is m_t\lsim175\GeV in
the no-scale flipped supergravity model. These bounds can be
strengthened for increasing chargino masses in the 50-100\GeV interval. In
particular, for m_t\gsim160\GeV, the Tevatron may be able to probe through
gluino() and squark() production up to m_{\tilde g}\approx
m_{\tilde q}\approx250\GeV, exploring at least half of the parameter space in
this model.Comment: 15 pages,(6 ps figures available upon request), TeX(harvmac),
CTP-TAMU-19/93, ACT-07/9
Predictions for Constrained Minimal Supersymmetry with Bottom-Tau Mass Unification
We examine the Constrained Minimal Supersymmetric Standard Model (CMSSM) with
an additional requirement of strict b - tau unification in the region of small
tan(beta). We find that the parameter space becomes completely limited below
about 1 TeV by physical constraints alone, without a fine-tuning constraint. We
study the resulting phenomenological consequences, and point out several ways
of falsifying the adopted b - tau unification assumption. We also comment on
the effect of a constraint from the non-observation of proton decay.Comment: Michigan preprint UM-TH-94-03, LaTeX, 18 pages with inline figures
(figures included in uuencoded file). Complete PS file also available by
anonymous FTP to williams.physics.lsa.umich.edu in
/pub/preprints/UM-TH-94-03.ps.Z or by e-mailing reques
Planck Scale Physics and the Testability of SU(5) Supergravity GUT
GUT scale threshold corrections in minimal SU(5) supergravity grand
unification are discussed. It is shown that predictions may be made despite
uncertainties associated with the high energy scale. A bound relating the
strong coupling constant to the mass scales associated with proton decay and
supersymmetry is derived, and a sensitive probe of the underlying theory is
outlined. In particular, low energy measurements can in principle determine the
presence of Planck scale () terms.Comment: 12 pages, REVTeX, 2 figures included in an uuencoded Z-compressed
PostScript file. Ready to print PostScript version (with figures) may be
picked up at ftp://phys.tamu.edu/urano/planck/paper_prep.p
Proton Decay and Cosmology Strongly Constrain the Minimal SU(5) Supergravity Model
We present the results of an extensive exploration of the five-dimensional
parameter space of the minimal supergravity model, including the
constraints of a long enough proton lifetime (\tau_p>1\times10^{32}\y) and a
small enough neutralino cosmological relic density ().
We find that the combined effect of these two constraints is quite severe,
although still leaving a small region of parameter space with m_{\tilde
g,\tilde q}<1\TeV. The allowed values of the proton lifetime extend up to
\tau_p\approx1\times10^{33}\y and should be fully explored by the
SuperKamiokande experiment. The proton lifetime cut also entails the following
mass correlations and bounds: m_h\lsim100\GeV,
m_\chi\approx{1\over2}m_{\chi^0_2}\approx0.15\gluino, , and m_\chi<85\,(115)\GeV,
m_{\chi^0_2,\chi^+_1}<165\,(225)\GeV for . Finally,
the {\it combined} proton decay and cosmology constraints predict that if
m_h\gsim75\,(80)\GeV then m_{\chi^+_1}\lsim90\,(110)\GeV for
. Thus, if this model is correct, at least one of
these particles will likely be observed at LEPII.Comment: 11 pages plus 5 figures (not included). CERN-TH.6628/92,
CTP-TAMU-61/92. A condensed version of this paper will appear in the
Proceedings of the XXVI International Conference on High Energy Physics,
Dallas--Texas, August 5--12, 199
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