1,798 research outputs found
A Classification and Analysis of Higgs-flavor Models
A classification is given of Higgs-flavor models. In these models, there are
several Higgs doublets in an irreducible multiplet R_{Phi} of a non-abelian
symmetry G_{Phi}, under which the quarks and leptons do not transform (thus
giving minimal flavor-changing for the fermions). It is found that different
G_{Phi} and R_{Phi} lead to very distinctive spectra of the extra Higgs
doublets, including different numbers of "sequential Higgs" and of "inert
Higgs" that could play the role of dark matter, different mass relations, and
different patterns of SU(2)_L-breaking splittings within the Higgs doublets.Comment: 35 page
Higher order Josephson effects
Gaussian linking of superconducting loops containing Josephson junctions with
enclosed magnetic fields give rise to interference shifts in the phase that
modulates the current carried through the loop, proportional to the magnitude
of the enclosed flux. We generalize these results to higher order linking of a
superconducting loop with several magnetic solenoids, and show there may be
interference shifts proportional to the product of two or more fluxes.Comment: 8 pages, 2 figure
Spacetime Emergence and General Covariance Transmutation
Spacetime emergence refers to the notion that classical spacetime "emerges"
as an approximate macroscopic entity from a non-spatio-temporal structure
present in a more complete theory of interacting fundamental constituents. In
this article, we propose a novel mechanism involving the "soldering" of
internal and external spaces for the emergence of spacetime and the twin
transmutation of general covariance. In the context of string theory, this
mechanism points to a critical four dimensional spacetime background.Comment: 11 pages, v2: version to appear in MPL
Simulating non-Markovian stochastic processes
We present a simple and general framework to simulate statistically correct
realizations of a system of non-Markovian discrete stochastic processes. We
give the exact analytical solution and a practical an efficient algorithm alike
the Gillespie algorithm for Markovian processes, with the difference that now
the occurrence rates of the events depend on the time elapsed since the event
last took place. We use our non-Markovian generalized Gillespie stochastic
simulation methodology to investigate the effects of non-exponential
inter-event time distributions in the susceptible-infected-susceptible model of
epidemic spreading. Strikingly, our results unveil the drastic effects that
very subtle differences in the modeling of non-Markovian processes have on the
global behavior of complex systems, with important implications for their
understanding and prediction. We also assess our generalized Gillespie
algorithm on a system of biochemical reactions with time delays. As compared to
other existing methods, we find that the generalized Gillespie algorithm is the
most general as it can be implemented very easily in cases, like for delays
coupled to the evolution of the system, where other algorithms do not work or
need adapted versions, less efficient in computational terms.Comment: Improvement of the algorithm, new results, and a major reorganization
of the paper thanks to our coauthors L. Lafuerza and R. Tora
Effective Potential of a Black Hole in Thermal Equilibrium with Quantum Fields
Expectation values of one-loop renormalized thermal equilibrium stress-energy
tensors of free conformal scalars, spin- fermions and U(1) gauge
fields on a Schwarzschild black hole background are used as sources in the
semi-classical Einstein equation. The back-reaction and new equilibrium metric
are solved for at for each spin field. The nature of the modified
black hole spacetime is revealed through calculations of the effective
potential for null and timelike orbits. Significant novel features affecting
the motions of both massive and massless test particles show up at lowest order
in , where is the renormalized black hole mass,
and is the Planck mass. Specifically, we find the tendency for
\underline{stable} circular photon orbits, an increase in the black hole
capture cross sections, and the existence of a gravitationally repulsive region
associated with the black hole which is generated from the U(1) back-reaction.
We also consider the back-reaction arising from multiple fields, which will be
useful for treating a black hole in thermal equilibrium with field ensembles
belonging to gauge theories.Comment: 25 pages (not including seven figures), VAND-TH-93-6. Typed in Latex,
uses RevTex macro
Muon anomalous magnetic moment in string inspired extended family models
We propose a standard model minimal extension with two lepton weak SU(2)
doublets and a scalar singlet to explain the deviation of the measured
anomalous magnetic moment of the muon from the standard model expectation. This
scheme can be naturally motivated in string inspired models such as E_6 and
AdS/CFT.Comment: 9 pages, RevTeX, 2 figures, version to be published in Phys. Rev.
Agents Play Mix-game
In mix-game which is an extension of minority game, there are two groups of
agents; group1 plays the majority game, but the group2 plays the minority game.
This paper studies the change of the average winnings of agents and
volatilities vs. the change of mixture of agents in mix-game model. It finds
that the correlations between the average winnings of agents and the mean of
local volatilities are different with different combinations of agent memory
length when the proportion of agents in group 1 increases. This study result
suggests that memory length of agents in group1 be smaller than that of agent
in group2 when mix-game model is used to simulate the financial markets.Comment: 8 pages, 6 figures, 3 table
Moduli in Exceptional SUSY Gauge Theories
The low energy structures of N=1 supersymmetric models with E_6, F_4 and E_7
gauge groups and fundamental irrep matter contents are studied herein. We
identify sets of gauge invariant composites which label all flat directions in
the confining/Higgs phases of these theories. The impossibility of mapping
several of these primary operators rules out previously conjectured exceptional
self duals reported in the literature.Comment: 20 pages, harvmac and tables macro
The Ubiquitous Inflaton in String-Inspired Models
A string theory based inflationary model is developed where the inflaton
interacts with a multitude of massive string level states causing dissipation
of vacuum energy. Inflation terminates in a warm Universe without the need for
reheating.Comment: In Press Physical Review Letters 1999, modified titl
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