1,813 research outputs found
What is the upper limit on the lightest supersymmetric Higgs mass?
In this talk the question of what is the upper bound on the lightest
supersymmetric Higgs mass, m_h is addressed. This question is relevant since
experimental lower bounds on m_h might implement, in the near future, exclusion
of supersymmetry. By imposing (perturbative) unification of the gauge couplings
at some high scale \simgt 10^{17} GeV, we have found that for a top-quark mass
M_t=175 GeV, and depending on the supersymmetric parameters, this bound can be
as high as 205 GeV.Comment: 7 pages, 4 figures, Work presented at PASCOS-98, March 22-29 199
Superfield approach to a novel symmetry for non-Abelian gauge theory
In the framework of superfield formalism, we demonstrate the existence of a
new local, covariant, continuous and nilpotent (dual-BRST) symmetry for the
BRST invariant Lagrangian density of a self-interacting two ()-dimensional (2D) non-Abelian gauge theory (having no interaction with
matter fields). The local and nilpotent Noether conserved charges corresponding
to the above continuous symmetries find their geometrical interpretation as the
translation generators along the odd (Grassmannian) directions of the four (-dimensional supermanifold.Comment: LaTeX, 12 pages, equations (4.2)--(4.6) correcte
Unified Models of Inflation and Quintessence
We apply an extended version of the method developed in reference
Int.J.Mod.Phys.D5(1996)71, to derive exact cosmological (flat)
Friedmann-Robertson-Walker solutions in RS2 brane models with a perfect fluid
of ordinary matter plus a scalar field fluid trapped on the brane. We found new
exact solutions, that can serve to unify inflation and quintessence in a common
theoretical framework.Comment: 8 pages, no figure
Brassica genomics: a complement to, and early beneficiary of, the Arabidopsis sequence.
Those studying the genus Brassica will be among the early beneficiaries of the now-completed Arabidopsis sequence. The remarkable morphological diversity of Brassica species and their relatives offers valuable opportunities to advance our knowledge of plant growth and development, and our understanding of rapid phenotypic evolution
Inflation from IIB Superstrings with Fluxes
We study the conditions needed to have an early epoch of inflationary
expansion with a potential coming from IIB superstring theory with fluxes
involving two moduli fields. The phenomenology of this potential is different
from the usual hybrid inflation scenario and we analize the possibility that
the system of field equations undergo a period of inflation in three different
regimes with the dynamics modified by a Randall-Sundrum II term in the
Friedmann equation. We find that the system can produce inflation and due to
the modification of the dynamics, a period of accelerated contraction can
follow or preceed this inflationary stage depending on the sign of one of the
parameters of the potential. We discuss on the viability of this model in a
cosmological context.Comment: 10 pages, 6 figure
On local scale symmetry in Riemann, Weyl and Riemann-Cartan geometry based gravitational theories and the role of the Noether current
In this paper, we delve into the significance of local scale symmetry and the
role of the associated Noether current, within Riemann, Weyl and Riemann-Cartan
geometry based gravitational theories. Our primary emphasis lies in conformal
coupling scalar gravitational theories and pure quadratic curvature theories,
wherein we examine the circumstances under which these can exhibit a local
scale symmetry. We show that local scale symmetry is associated with vanishing
Noether current whenever there are not new propagating (gravitational) degrees
of freedom beyond the two polarizations of the massless graviton. In contrast,
in local scale invariant theories where there are more than two propagating
gravitational degrees of freedom, local scale symmetry is associated with
nonvanishing Noether current.Comment: 15 page
On boundary terms and conformal transformations in curved space-times
We intend to clarify the interplay between boundary terms and conformal
transformations in scalar-tensor theories of gravity. We first consider the
action for pure gravity in five dimensions and show that, on compactifing a la
Kaluza-Klein to four dimensions, one obtains the correct boundary terms in the
Jordan (or String) Frame form of the Brans-Dicke action. Further, we analyze
how the boundary terms change under the conformal transformations which lead to
the Pauli (or Einstein) frame and to the non-minimally coupled massless scalar
field. In particular, we study the behaviour of the total energy in
asymptotically flat space-times as it results from surface terms in the
Hamiltonian formalism.Comment: LaTeX 2e, 12 pages, no figure
Higher Order Stability of a Radiatively Induced 220 GeV Higgs Mass
The effective potential for radiatively broken electroweak symmetry in the
single Higgs doublet Standard Model is explored to four sequentially subleading
logarithm-summation levels (5-loops) in the dominant Higgs self-interaction
couplant . We augment these results with all contributing leading
logarithms in the remaining large but sub-dominant Standard Model couplants
(t-quark, QCD and gauge couplants) as well as next to
leading logarithm contributions from the largest of these, the t-quark and QCD
couplants. Order-by-order stability is demonstrated for earlier leading
logarithm predictions of an order 220 GeV Higgs boson mass in conjunction with
fivefold enhancement of the value for over that anticipated from
conventional spontaneous symmetry breaking.Comment: revtex, 6 pages. Analysis and text is expanded in revised versio
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