9,299 research outputs found
MSSM inflaton: SUSY dark matter and LHC
In this talk we will discuss how inflation can be embedded within a minimal
extension of the Standard Model where the inflaton carries the Standard Model
charges. There is no need of an ad-hoc scalar field to be introduced in order
to explain the temperature anisotropy of the cosmic microwave background
radiation, all the ingredients are present within a minimal supersymmetric
Standard Model. For the first time inflaton properties can be directly linked
to the particle phenomenology, dark matter, and the baryons of the Standard
Model.Comment: 6 Pages, UCLA DM 200
Aspects of brane-antibrane inflation
I describe a dynamical mechanism for solving the fine-tuning problem of
brane-antibrane inflation. By inflating with stacks of branes and antibranes,
the branes can naturally be trapped at a metastable minimum of the potential.
As branes tunnel out of this minimum, the shape of the potential changes to
make the minimum shallower. Eventually the minimum disappears and the remaining
branes roll slowly because the potential is nearly flat. I show that even with
a small number of branes, there is a good chance of getting enough inflation.
Running of the spectral index is correlated with the tilt in such a way as to
provide a test of the model by future CMB experiments.Comment: 6 pages, 5 figures; proceedings of Theory Canada 1 conference, 2-5
June 2005, UBC, Vancouve
A Decade of Dark Energy: 1998 - 2008
The years 1998 to 2008 were very exciting years for cosmology. It was a
pleasure to accept this invitation to describe my contributions to the
development of our knowledge and understanding of the universe over the course
of the past decade. Here, I begin by describing some of my work on radio
galaxies as a modified standard yardstick and go on to describe
model-independent studies of the accelerating universe and the properties of
the dark energy. During the course of these studies, I came upon interesting
ways to study the spin and other properties of supermassive black holes, some
of which are briefly mentioned.Comment: Proceedings of the 2008 UCLA Conference "Dark Matter and Dark Energy
in the Universe," submitted to AIP Conference Proceedings, 6 page
A Neutrino-Factory Muon Storage Ring to Provide Beams for Multiple Detectors Around the World
We briefly discuss the physics motivation for a neutrino factory with varying
baseline distances of about 1000 to 9000 km. We describe the amount of non
planarity of the storage ring required to service three or four detectors at
once. A novel bowtie storage ring is described that could in part provide these
beams; a preliminary lattice design is given. We give the space angles between
the various detector locations and possible sites for neutrino factories.
Finally we describe detectors at the Gran Sasso Laboratory and at a new
laboratory near Carlsbad, NM to observe the neutrino interactions with wrong
sign leptons.Comment: 8 pages. Presented at the 5th Int. Conf. sponsored by UCLA on the
Physics Potential and Develoment of mu^+mu^- Colliders (San Francisco,
December 15-17, 1999) and to be published in the Proceedings by AI
CF6 High Pressure Compressor and Turbine Clearance Evaluations
In the CF6 Jet Engine Diagnostics Program the causes of performance degradation were determined for each component of revenue service engines. It was found that a significant contribution to performance degradation was caused by increased airfoil tip radial clearances in the high pressure compressor and turbine areas. Since the influence of these clearances on engine performance and fuel consumption is significant, it is important to accurately establish these relatonships. It is equally important to understand the causes of clearance deterioration so that they can be reduced or eliminated. The results of factory engine tests run to enhance the understanding of the high pressure compressor and turbine clearance effects on performance are described. The causes of clearance deterioration are indicated and potential improvements in clearance control are discussed
Dilaton Stabilization in Brane Gas Cosmology
Brane Gas Cosmology is an M-theory motivated attempt to reconcile aspects of
the standard cosmology based on Einstein's theory of general relativity.
Dilaton gravity, when incorporating winding p-brane states, has verified the
Brandenberger--Vafa mechanism --a string-motivated conjecture which explains
why only three of the nine spatial dimensions predicted by string theory grow
large. Further investigation of this mechanism has argued for a hierarchy of
subspaces, and has shown the internal directions to be stable to initial
perturbations. These results, however, are dependent on a rolling dilaton, or
varying strength of Newton's gravitational constant. In these proceedings we
show that it is not possible to stabilize the dilaton and maintain the
stability of the internal directions within the standard Brane Gas Cosmology
setup.Comment: 6 pages, no figures. To appear in the Proceedings of MRST 2004, held
at Concordia University, Montreal, QC, 12-14 May 200
Gravitational Field of Spherical Branes
The warped solution of Einstein's equations corresponding to the spherical
brane in five-dimensional AdS is considered. This metric represents interiors
of black holes on both sides of the brane and can provide gravitational
trapping of physical fields on the shell. It is found the analytic form of the
coordinate transformations from the Schwartschild to co-moving frame that
exists only in five dimensions. It is shown that in the static coordinates
active gravitational mass of the spherical brane, in agreement with Tolman's
formula, is negative, i.e. such objects are gravitationally repulsive.Comment: Minor corrections, 8 pages, the version accepted by Mod. Phys. Lett.
Leptogenesis with Left-Right domain walls
The presence of domain walls separating regions of unbroken and
is shown to provide necessary conditions for leptogenesis which
converts later to the observed Baryon aymmetry. The strength of lepton number
violation is related to the majorana neutrino mass and hence related to current
bounds on light neutrino masses. Thus the observed neutrino masses and the
Baryon asymmetry can be used to constrain the scale of Left-Right symmetry
breaking.Comment: References added, To appear in Praman
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