2,063 research outputs found
Baryons and baryonic matter in the large Nc and heavy quark limits
This paper explores properties of baryons and finite density baryonic matter
in an artificial world in which Nc, the number of colors, is large and the
quarks of all species are degenerate and much larger than {\Lambda}_QCD. It has
long been known that in large Nc QCD, baryons composed entirely of heavy quarks
are accurately described in the mean-field approximation. However, the detailed
properties of baryons in the combined large Nc and heavy quark limits have not
been fully explored. Here some basic properties of baryons are computed using a
variational approach. At leading order in both the large Nc and heavy quark
expansions the baryon mass is computed explicitly as is the baryon form factor.
Baryonic matter, the analog of nuclear matter in this artificial world, should
also be well described in the mean-field approximation. In the special case
where all baryons have an identical spin flavor structure, it is shown that in
the formal heavy quark and large Nc limit interactions between baryons are
strictly repulsive at low densities. The energy per baryon is computed in this
limit and found to be exponentially small. It is shown that when the
restriction to baryons with an identical spin-flavor structure is dropped, a
phase of baryonic matter exists with a density of 2Nf times that for the
restricted case but with the same energy (where Nf is the number of degenerate
flavors). It is shown that this phase is at least metastable.Comment: 19 page
Mergers Simulation and Demand Analysis for the U.S. Carbonated Soft Drink Industry
Replaced with revised version of paper on 09/29/09. Former title: Mergers, Price Competition for the U.S. Carbonated Soft Drink Industrydistance metrics, demand, merger simulation, Agribusiness, Industrial Organization, Marketing, L13, C14,
Multivariate phase space reconstruction by nearest neighbor embedding with different time delays
A recently proposed nearest neighbor based selection of time delays for phase
space reconstruction is extended to multivariate time series, with an iterative
selection of variables and time delays. A case study of numerically generated
solutions of the x- and z coordinates of the Lorenz system, and an application
to heart rate and respiration data, are used for illustration.Comment: 4 pages, 3 figure
Correlations of non-affine displacements in metallic glasses through the yield transition
We study correlations of non-affine displacement during simple shear
deformation of Cu-Zr bulk metallic glasses in molecular dynamics calculations.
In the elastic regime, our calculations show exponential correlation with a
decay length that we interpret as the size of a shear transformation zone in
the elastic regime. This correlation length becomes system-size dependent
beyond the yield transition as our calculation develops a shear band,
indicative of a diverging length scale. We interpret these observations in the
context of a recent proposition of yield as a first-order phase transition.Comment: 23 pages, 8 figure
Noise-Induced Desynchronization and Stochastic Escape from Equilibrium in Complex Networks
Complex physical systems are unavoidably subjected to external environments
not accounted for in the set of differential equations that models them. The
resulting perturbations are standardly represented by noise terms. We derive
conditions under which such noise terms perturb the dynamics strongly enough
that they lead to stochastic escape from the initial basin of attraction of an
initial stable equilibrium state of the unperturbed system. Focusing on
Kuramoto-like models we find in particular that, quite counterintuitively,
systems with inertia leave their initial basin faster than or at the same time
as systems without inertia, except for strong white-noise perturbations.Comment: Main text: 5 pages, 4 figures. Supplemental material: 6 pages, 7
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