5,061 research outputs found
Electroweak phase transition by four dimensional simulations
The finite temperature phase transition in the SU(2)-Higgs model at a Higgs
boson mass GeV is studied in numerical simulations on four
dimensional lattices with time-like extensions up to . is
extrapolated to the continuum limit and a comparison with the perturbative
prediction is made. A one-loop calculation to the coupling anisotropies of the
SU(2)-Higgs model on lattices with asymmetric lattice spacings is presented.
Our numerical simulations show that the above perturbative result is applicable
in the phenomenologically interesting parameter region.Comment: 3 pages, Latex, 3 figures, Talk presented at LATTICE96(electroweak)
by Z. Fodo
Wilson Loops in string duals of Walking and Flavored Systems
We consider the VEV of Wilson loop operators by studying the behavior of
string probes in solutions of Type IIB string theory generated by Nc D5 branes
wrapped on an internal manifold. In particular, we focus on solutions to the
background equations that are dual to field theories with a walking gauge
coupling as well as for flavored systems. We present in detail our walking
solution and emphasize various general aspects of the procedure to study Wilson
loops using string duals. We discuss the special features that the strings show
when probing the region associated with the walking of the field theory
coupling.Comment: 28 pages. Various figures. Version to be published
Phase Fluctuations near the Chiral Critical Point
The Helmholtz free energy density is parametrized as a function of
temperature and baryon density near the chiral critical point of QCD. The
parametrization incorporates the expected critical exponents and amplitudes. An
expansion away from equilibrium states is achieved with Landau theory. This is
used to calculate the probability that the system is found at a density other
than the equilibrium one. Such fluctuations are predicted to be very large in
heavy ion collisions.Comment: 7 pages, 8 figures, Winter Workshop on Nuclear Dynamics 201
Cognitive Computation sans Representation
The Computational Theory of Mind (CTM) holds that cognitive processes are essentially computational, and hence computation provides the scientific key to explaining mentality. The Representational Theory of Mind (RTM) holds that representational content is the key feature in distinguishing mental from non-mental systems. I argue that there is a deep incompatibility between these two theoretical frameworks, and that the acceptance of CTM provides strong grounds for rejecting RTM. The focal point of the incompatibility is the fact that representational content is extrinsic to formal procedures as such, and the intended interpretation of syntax makes no difference to the execution of an algorithm. So the unique 'content' postulated by RTM is superfluous to the formal procedures of CTM. And once these procedures are implemented in a physical mechanism, it is exclusively the causal properties of the physical mechanism that are responsible for all aspects of the system's behaviour. So once again, postulated content is rendered superfluous. To the extent that semantic content may appear to play a role in behaviour, it must be syntactically encoded within the system, and just as in a standard computational artefact, so too with the human mind/brain - it's pure syntax all the way down to the level of physical implementation. Hence 'content' is at most a convenient meta-level gloss, projected from the outside by human theorists, which itself can play no role in cognitive processing
The quadrupole moment of slowly rotating fluid balls
In this paper we use the second order formalism of Hartle to study slowly and
rigidly rotating stars with focus on the quadrupole moment of the object. The
second order field equations for the interior fluid are solved numerically for
different classes of possible equations of state and these solutions are then
matched to a vacuum solution that includes the general asymptotically flat
axisymmetric metric to second order, using the Darmois-Israel procedure. For
these solutions we find that the quadrupole moment differs from that of the
Kerr metric, as has also been found for some equations of state in other
studies. Further we consider the post-Minkowskian limit analytically. In the
paper we also illustrate how the relativistic multipole moments can be
calculated from a complex gravitational potential.Comment: 13 pages, 5 figure
Numerical tests of the electroweak phase transition and thermodynamics of the electroweak plasma
The finite temperature phase transition in the SU(2) Higgs model at a Higgs
boson mass GeV is studied in numerical simulations on
four-dimensional lattices with time-like extensions up to . The effects
of the finite volume and finite lattice spacing on masses and couplings are
studied in detail. The errors due to uncertainties in the critical hopping
parameter are estimated. The thermodynamics of the electroweak plasma near the
phase transition is investigated by determining the relation between energy
density and pressure.Comment: latex2e, 32 pages, 11 figures with epsfig; A few comments and a new
table are adde
On the non-monotonic variation of the entrainment buoyancy flux with wind shear
The magnitude of the entrainment buoyancy flux, and hence the growth rate of the convective boundary layer, does not increase monotonically with wind shear. Explanations for this have previously been based on wind-shear effects on the turbulence kinetic energy. By distinguishing between turbulent and non-turbulent regions, we provide an alternative explanation based on two competing wind-shear effects: the initial decrease in the correlation between buoyancy and vertical velocity fluctuations, and the increase in the turbulent area fraction. The former is determined by the change in the dominant forcing; without wind shear, buoyancy fluctuations drive vertical velocity fluctuations and the two are thus highly correlated; with wind shear, vertical velocity fluctuations are partly determined by horizontal velocity fluctuations via the transfer of kinetic energy through the pressure-strain correlation, thus reducing their correlation with the buoyancy field. The increasing turbulent area fraction, on the other hand, is determined by the increasing shear production of turbulence kinetic energy inside the entrainment zone. We also show that the dependence of these conditional statistics on the boundary-layer depth and on the magnitude of the wind shear can be captured by a single non-dimensional variable, which can be interpreted as an entrainment-zone Froude number
The QCD phase diagram at nonzero quark density
We determine the phase diagram of QCD on the \mu-T plane for small to
moderate chemical potentials. Two transition lines are defined with two
quantities, the chiral condensate and the strange quark number susceptibility.
The calculations are carried out on N_t =6,8 and 10 lattices generated with a
Symanzik improved gauge and stout-link improved 2+1 flavor staggered fermion
action using physical quark masses. After carrying out the continuum
extrapolation we find that both quantities result in a similar curvature of the
transition line. Furthermore, our results indicate that in leading order the
width of the transition region remains essentially the same as the chemical
potential is increased.Comment: 12 pages, 6 figure
Technicolor and Beyond: Unification in Theory Space
The salient features of models of dynamical electroweak symmetry breaking are
reviewed. The ideal walking idea is introduced according to which one should
carefully take into account the effects of the extended technicolor dynamics on
the technicolor dynamics itself. The effects amount at the enhancement of the
anomalous dimension of the mass of the techniquarks allowing to decouple the
Flavor Changing Neutral Currents problem from the one of the generation of the
top mass. Precision data constraints are reviewed focussing on the latest
crucial observation that the S-parameter can be computed exactly near the upper
end of the conformal window (Conformal S-parameter) with relevant consequences
on the selection of nature's next strong force. We will then introduce the
Minimal Walking Technicolor (MWT) models. In the second part of this review we
consider the interesting possibility to marry supersymmetry and technicolor.
The reason is to provide a unification of different extensions of the standard
model. For example, this means that one can recover, according to the
parameters and spectrum of the theory distinct extensions of the standard
model, from supersymmetry to technicolor and unparticle physiscs. A surprising
result is that a minimal (in terms of the smallest number of fields)
supersymmetrization of the MWT model leads to the maximal supersymmetry in four
dimensions, i.e. N=4 SYM.Comment: Extended version of the PASCOS10 proceedings for the Plenary Tal
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