3,688 research outputs found
Single Leptoquark Production at and Colliders
We consider single production of leptoquarks (LQ's) at and
colliders, for two values of the centre-of-mass energy,
GeV and 1 TeV. We find that LQ's which couple within the first
generation are observable for LQ masses almost up to the kinematic limit, both
at and colliders, for the LQ coupling strength equal to
. The cross sections for single production of - and
-generation LQ's at colliders are too small to be observable.
In collisions, on the other hand, -generation LQ's with
masses much larger than can be detected. However,
-generation LQ's can be seen at colliders only for
masses at most , making their observation more probable via the
pair production mechanism.Comment: plain TeX, 14 pages, 6 figures (not included but available on
request), some minor changes to the text, one reference added, figures and
conclusions unchanged, UdeM-LPN-TH-93-152, McGill-93/2
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
The visible effect of a very heavy magnetic monopole at colliders
If a heavy Dirac monopole exists, the light-to-light scattering below the
monopole production threshold is enhanced due to strong coupling of monopoles
to photons. At the next Linear Collider with electron beam energy 250 GeV this
photon pair production could be observable at monopole masses less than 2.5-6.4
TeV in the mode or 3.7-10 TeV in the mode, depending on
the monopole spin. At the upgraded Tevatron such an effect is expected to be
visible at monopole masses below 1-2.5 TeV. The strong dependence on the
initial photon polarizations allows to find the monopole spin in experiments at
and colliders. We consider the production and
the production at and or colliders via the
same monopole loop. The possibility to discover these processes is
significantly lower than that of the case.Comment: 18 pages, 2 figures, RevTe
Chain length dependence of the polymer-solvent critical point parameters
We report grand canonical Monte Carlo simulations of the critical point
properties of homopolymers within the Bond Fluctuation model. By employing
Configurational Bias Monte Carlo methods, chain lengths of up to N=60 monomers
could be studied. For each chain length investigated, the critical point
parameters were determined by matching the ordering operator distribution
function to its universal fixed-point Ising form. Histogram reweighting methods
were employed to increase the efficiency of this procedure. The results
indicate that the scaling of the critical temperature with chain length is
relatively well described by Flory theory, i.e. \Theta-T_c\sim N^{-0.5}. The
critical volume fraction, on the other hand, was found to scale like \phi_c\sim
N^{-0.37}, in clear disagreement with the Flory theory prediction \phi_c\sim
N^{-0.5}, but in good agreement with experiment. Measurements of the chain
length dependence of the end-to-end distance indicate that the chains are not
collapsed at the critical point.Comment: 13 Pages Revtex, 9 epsf embedded figs. gzipped tar file. To appear in
J. Chem. Phy
Dependence of the critical temperature on the Higgs field reparametrization
We show that, despite of the reparametrization symmetry of the Lagrangian
describing the interaction between a scalar field and gauge vector bosons, the
dynamics of the Higgs mechanism is really affected by the representation gauge
chosen for the Higgs field. Actually, we find that, varying the parametrization
for the two degrees of freedom of the complex scalar field, we obtain different
expressions for the Higgs mass: in its turn this entails different expressions
for the critical temperatures, ranging from zero to a maximum value, as well as
different expressions for other basic thermodynamical quantities.Comment: revtex, 12 pages, 2 eps figure
The dependence of the hard diffractive photoproduction of vector meson or photon and the range of pQCD validity
We consider two coupled problems.
We study the dependence on photon virtuality for the semihard
quasi--elastic photoproduction of neutral vector mesons on a quark, gluon or
real photon (at
GeV)). To this end we calculate the corresponding amplitudes (in an
analytical form) in the lowest nontrivial approximation of perturbative QCD. It
is shown that the amplitude for the production of light meson varies very
rapidly with the photon virtuality near .
We estimate the bound of the pQCD validity region for such processes. For the
real incident photon the obtained bound for the meson production is very
high. This bound decreases fast with the increase of , and we expect that
the virtual photoproduction at HERA gives opportunity to test the pQCD results.
The signature of this region is discussed. For the hard Compton effect the pQCD
should work good at not too high , and this effect seems measurable
at HERA.Comment: ReVTeX, 36 pages, 5 Postscript figures, uses epsf.st
Vortex Origin of Tricritical Point in Ginzburg-Landau Theory
Motivated by recent experimental progress in the critical regime of
high- superconductors we show how the tricritical point in a
superconductor can be derived from the Ginzburg-Landau theory as a consequence
of vortex fluctuations. Our derivation explains why usual renormalization group
arguments always produce a first-order transition, in contrast to experimental
evidence and Monte Carlo simulations.Comment: 4 pages,1 figur
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Modelling DoS Attacks & Interoperability in the Smart Grid
Smart grids perform the crucial role of delivering electricity to millions of people and driving today’s industries. However, the integration of physical operational technology (OT) with IT systems introduces many security challenges. Denial-of-Service (DoS) is a well-known IT attack with a large potential for damage within the smart grid. Whilst DoS is relatively well-understood in IT networks, the unique characteristics and requirements of smart grids bring up new challenges. In this paper, we examine this relationship and propose the OT impact chain to capture possible sequences of events resulting from an IT-side DoS attack. We then apply epidemic principles to explore the same dynamics using the proposed S-A-C model
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