11 research outputs found
Chaotic scalar fields as models for dark energy
We consider stochastically quantized self-interacting scalar fields as
suitable models to generate dark energy in the universe. Second quantization
effects lead to new and unexpected phenomena is the self interaction strength
is strong. The stochastically quantized dynamics can degenerate to a chaotic
dynamics conjugated to a Bernoulli shift in fictitious time, and the right
amount of vacuum energy density can be generated without fine tuning. It is
numerically observed that the scalar field dynamics distinguishes fundamental
parameters such as the electroweak and strong coupling constants as
corresponding to local minima in the dark energy landscape. Chaotic fields can
offer possible solutions to the cosmological coincidence problem, as well as to
the problem of uniqueness of vacua.Comment: 30 pages, 3 figures. Replaced by final version accepted by Phys. Rev.
Angular Dependence of Neutrino Flux in KM3 Detectors in Low Scale Gravity Models
Cubic kilometer neutrino telescopes are capable of probing fundamental
questions of ultra-high energy neutrino interactions. There is currently great
interest in neutrino interactions caused by low-scale, extra dimension models.
Above 1 PeV the cross section in low scale gravity models rises well above the
total Standard Model cross section. We assess the observability of this effect
in the 1 PeV - 100 PeV energy range of kilometer-scale detectors with several
new points of emphasis that hinge on enhanced neutral current cross sections. A
major point is the importance of ``feed-down'' regeneration of upward neutrino
flux, driven by new-physics neutral current interactions in the flux evolution
equations. Feed-down is far from negligible, and it is essential to include its
effect. We then find that the angular distribution of events has high
discriminating value in separating models. In particular the ``up-to-down''
ratio between upward and downward-moving neutrino fluxes is a practical
diagnostic tool which can discriminate between models in the near future. The
slope of the angular distribution, in the region of maximum detected flux, is
also substantially different in low-scale gravity and the Standard Model. These
observables are only weakly dependent on astrophysical flux uncertainties. We
conclude that angular distributions can reveal a breakdown of the Standard
Model and probe the new physics beyond, as soon as data become available.Comment: 25 pages, 6 figures, discussion of calculations expanded, references
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Large Neutrino Mixing from Renormalization Group Evolution
The renormalization group evolution equation for two neutrino mixing is known
to exhibit nontrivial fixed point structure corresponding to maximal mixing at
the weak scale. The presence of the fixed point provides a natural explanation
of the observed maximal mixing of if the and
are assumed to be quasi-degenerate at the seesaw scale without
constraining on the mixing angles at that scale. In particular, it allows them
to be similar to the quark mixings as in generic grand unified theories. We
discuss implementation of this program in the case of MSSM and find that the
predicted mixing remains stable and close to its maximal value, for all
energies below the (TeV) SUSY scale. We also discuss how a particular
realization of this idea can be tested in neutrinoless double beta decay
experiments.Comment: Latex file, 21 pages and 4 ps figures include
Lepton flavor violation two-body decays of quarkoniums
In this paper we firstly study various model-independent bounds on lepton
flavor violation (LFV) in processes of , and
two-body decays, then calculate their branch ratios % By using the constraints
from other ways, we obtain %the indirect bounds of in models of the leptoquark, violating
MSSM and topcolor assisted technicolor(TC2) models.Comment: 14 pages, 4 figures, submitted to PR
Implications of supersymmetric models with natural R-parity conservation
In the minimal supersymmetric standard model, the conservation of R-parity is
phenomenologically desirable, but is ad hoc in the sense that it is not
required for the internal consistency of the theory. However, if B-L is gauged
at very high energies, R-parity will be conserved automatically and exactly,
provided only that all order parameters carry even integer values of 3(B-L). We
propose a minimal extension of the supersymmetric standard model in which
R-parity conservation arises naturally in this way. This approach predicts the
existence of a very weakly coupled, neutral chiral supermultiplet of particles
with electroweak-scale masses and lifetimes which may be cosmologically
interesting. Neutrino masses arise via an intermediate-scale seesaw mechanism,
and a solution to the problem is naturally incorporated. The apparent
unification of gauge couplings at high energies is shown to be preserved in
this approach. We also discuss a next-to-minimal extension, which predicts a
pair of electroweak-scale chiral supermultiplets with electric charge 2.Comment: 19 pages, plain TeX, no figure
Next-to-Minimal Supersymmetric Standard Model with the Gauge Mediation of Supersymmetry Breaking
We study the Next-to-Minimal Supersymmetric Standard Model (NMSSM) as the
simplest candidate solution to the -problem in the context of the gauge
mediation of supersymmetry breaking (GMSB). We first review various proposals
to solve the -problem in models with the GMSB. We find none of them
entirely satisfactory and point out that many of the scenarios still lack
quantitative studies, and motivate the NMSSM as the simplest possible solution.
We then study the situation in the Minimal Supersymmetric Standard Model (MSSM)
with the GMSB and find that an order 10% cancellation is necessary between the
-parameter and the soft SUSY-breaking parameters to correctly reproduce
. Unfortunately, the NMSSM does not to give a phenomenologically viable
solution to the -problem. We present quantitative arguments which apply
both for the low-energy and high-energy GMSB and prove that the NMSSM does not
work for either case. Possible modifications to the NMSSM are then discussed.
The NMSSM with additional vector-like quarks works phenomenologically, but
requires an order a few percent cancellation among parameters. We point out
that this cancellation has the same origin as the cancellation required in the
MSSM.Comment: 36 pages, LaTeX, epsf.sty, 5 figures, references added, comments on
some other papers based on our misundestanding corrected, none of our results
change