97 research outputs found
Do internal symmetries get restored in hot and dense SUSY?
I offer some computational details and useful and concise formulae to
calculate the effective potential for a general abelian supersymmetric model at
high temperature and density. It will be shown that such cases are very good
candidates for symmetry nonrestoration at high temperature, providing large
densities are present.Comment: 3 pages, uses sprocl.sty, talk given at the International Workshop
COSMO97 on Particle Physics and the Early Universe, 15-19 September 1997,
Ambleside, Lake District, England, to be published in the Proceeding
High Temperature Symmetry Nonrestoration
This is a short review on the subject of symmetry nonrestoration at high
temperature. Special emphasis is put on experimental discoveries and different
theoretical mechanisms. At the end, possible cosmological applications are
briefly mentioned.Comment: 7 pages; plenary talk at COSMO99, Trieste, Italy, Sep 27 - Oct 2,
1999; to appear in the proceedings; minor text changes and new references
adde
Proton decay, supersymmetry breaking and its mediation
We study the breaking of supersymmetry and its transmission to the light
states in the context of the minimal SU(5) grand unified theory, with no
additional singlets. This simple theory can be taken as a prototype for a
program of breaking simultaneously grand unified symmetry and supersymmetry.
The main predictions are: (i) d=6 proton decay is completely negligible and d=5
is in accord with experiment, (ii) supersymmetry breaking is mainly mediated by
gravity.Comment: 18 page
Towards the minimal renormalizable supersymmetric model
We find an explicit renormalizable supersymmetric model with all the
ingredients for being realistic. It consists of the Higgs sector
, which breaks directly to the
Standard Model gauge group. Three copies of dimensional representations
then describe the matter sector, while an extra pair is
needed to successfully split the Standard Model Higgs doublet from the heavy
Higgs triplet. We perform the analysis of the vacuum structure and the Yukawa
sector of this model, as well as compute contributions to proton decay. Also,
we show why some other simpler models fail to be realistic at the
renormalizable level.Comment: 36 pages, a new section on proton decay added, new reference, results
unchanged. To be published in JHE
Hidden flavor symmetries of SO(10) GUT
The Yukawa interactions of the SO(10) GUT with fermions in 16-plets (as well
as with singlets) have certain intrinsic ("built-in") symmetries which do not
depend on the model parameters. Thus, the symmetric Yukawa interactions of the
10 and 126 dimensional Higgses have intrinsic discrete
symmetries, while the antisymmetric Yukawa interactions of the 120 dimensional
Higgs have a continuous SU(2) symmetry. The couplings of SO(10) singlet
fermions with fermionic 16-plets have symmetry. We consider a
possibility that some elements of these intrinsic symmetries are the residual
symmetries, which originate from the (spontaneous) breaking of a larger
symmetry group . Such an embedding leads to the determination of certain
elements of the relative mixing matrix between the matrices of Yukawa
couplings , , , and consequently, to restrictions of
masses and mixings of quarks and leptons. We explore the consequences of such
embedding using the symmetry group conditions. We show how unitarity emerges
from group properties and obtain the conditions it imposes on the parameters of
embedding. We find that in some cases the predicted values of elements of
are compatible with the existing data fits. In the supersymmetric version of
SO(10) such results are renormalization group invariant.Comment: 28 pages, a reference added, typos corrected, to be published in NP
Scalar potentials, propagators and global symmetries in AdS/CFT
We study the transition of a scalar field in a fixed background
between an extremum and a minimum of a potential. We first prove that two
conditions must be met for the solution to exist. First, the potential involved
cannot be generic, i.e. a fine-tuning of their parameters is mandatory. Second,
at least in some region its second derivative must have a negative upper limit
which depends only on the dimensionality . We then calculate the boundary
propagator for small momenta in two different ways: first in a WKB
approximation, and second with the usual matching method, generalizing the
known calculation to arbitrary order. Finally, we study a system with
spontaneously broken non-Abelian global symmetry, and show in the holographic
language why the Goldstone modes appear.Comment: 26 pages - Invited contribution for the Central European Journal of
Physics, topical issue devoted to "Cosmology and Particle Physics beyond
Standard Models". Some parts overlap with 1304.3051v1, which has been
replaced by the published versio
- …