7,691 research outputs found
Electroweak Baryogenesis in the Minimal Supersymmetric Standard Model
I describe work done in collaboration with M. Joyce and K. Kainulainen on (1)
the strength of the electroweak phase transition in the MSSM and (2) the
mechanism for producing the baryon asymmetry during the phase transition. In
the former we compare the effective potential and dimensional reduction methods
for describing the phase transition and search the parameter space of the MSSM
for those values where it is strong enough. In the latter we give a systematic
computation of the baryon asymmetry due the CP-violating force acting on
charginos in the vicinity of the bubble wall. We find that a light right-handed
stop, a light Higgs boson, and a large phase in the mu parameter, are the main
necessary ingredients for producing the baryon asymmetry.Comment: 5 pages, Latex; Talk given at the Eotvos Conference in Science,
Strong and Electroweak Matter '97, Eger, Hungary, 21-25 May 1997; and at the
19th Annual MRST (Montreal-Rochester-Syracuse-Toronto) High-energy Theory
Meeting, Syracuse, New York, 12-13 May 199
Tachyon Defect Formation and Reheating in Brane-Antibrane Inflation
We study analytically the dynamical formation of lower dimensional branes at
the endpoint of brane-antibrane inflation through the condensation of
topological defects of the tachyon field which describes the instability of the
initial state. We then use this information to quantify the efficiency of the
reheating which is due to the coupling of time dependent tachyon background to
massless gauge fields which will be localized on the final state branes. We
improve upon previous estimates indicating that this can be an efficient
reheating mechanism for observers on the brane.Comment: 9 pages. Talk given at the 26th annual
Montreal-Rochester-Syracuse-Toronto Conference on High-Energy Physics: MRST
200
Supersymmetric Electroweak Baryogenesis in the WKB approximation
We calculate the baryon asymmetry generated at the electroweak phase
transition in the minimal supersymmetric standard model, treating the particles
in a WKB approximation in the bubble wall background. A set of diffusion
equations for the particle species relevant to baryon generation, including
source terms arising from the CP violation associated with the complex phase
of the parameter, are derived from Boltzmann equations, and
solved. The conclusion is that must be \gsim 0.1 to generate a
baryon asymmetry consistent with nucleosynthesis. We compare our results to
several other recent computations of the effect, arguing that some are
overestimates.Comment: 12 pages, 1 figure, corrected some criticisms of hep-ph/9702409; to
appear in Phys. Lett.
Status of Electroweak Phase Transition and Baryogenesis
I review recent progress on the electroweak phase transition and
baryogenesis, focusing on the minimal supersymmetric standard model as the
source of new physics.Comment: 10 pp, 6 figures; plenary talk given at 6th Workshop on High Energy
Physics Phenomenology, 4 Jan. 2000, Chennai, India. v.2: added reference
One hundred angstrom niobium wire
Composite of fine niobium wires in copper is used to study the size and proximity effects of a superconductor in a normal matrix. The niobium rod was drawn to a 100 angstrom diameter wire on a copper tubing
An optimistic CoGeNT analysis
Inspired by a recently proposed model of millicharged atomic dark matter
(MADM), we analyze several classes of light dark matter models with respect to
CoGeNT modulated and unmodulated data, and constraints from CDMS, XENON10 and
XENON100. After removing the surface contaminated events from the original
CoGeNT data set, we find an acceptable fit to all these data (but with the
modulating part of the signal making a statistically small contribution), using
somewhat relaxed assumptions about the response of the null experiments at low
recoil energies, and postulating an unknown modulating background in the CoGeNT
data at recoil energies above 1.5 keVee. We compare the fits of MADM---an
example of inelastic magnetic dark matter---to those of standard elastically
and inelastically scattering light WIMPs (eDM and iDM). The iDM model gives the
best fit, with MADM close behind. The dark matter interpretation of the DAMA
annual modulation cannot be made compatible with these results however. We find
that the inclusion of a tidal debris component in the dark matter phase space
distribution improves the fits or helps to relieve tension with XENON
constraints.Comment: 16 pages, 11 figures; v2: added discussion of dipole-dipole
scattering and details of matrix elements; also implications of XENON100 2012
limits. Qualitative conclusions unchanged. Published versio
Recent Progress in Baryogenesis
I give a synopsis, specifically aimed at nonexperts, of some of the recent developments in electroweak baryogenesis. The focus of the talk is on the present status of electroweak baryogenesis in supersymmetric models, since this is a plausible and realistic possibility that is currently being probed by experimental searches for the Higgs boson and the top squark. The question of whether it is viable to have a period of color-breaking during the electroweak phase transition is also discussed
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