202 research outputs found
Dynamics of a Disoriented Chiral Condensate
We use the linear model to analyse the dynamics of a disoriented
chiral condensate. For idealized boundary conditions appropriate to high energy
collisions, the problem can be reduced to a one dimensional one. The evolution
of the chiral state is then that of a simple dynamical system and can be
studied analytically.Comment: 14 pages Latex, LPTHE Orsay 94/18 , SPhT T94/01
The Strong-Coupling Expansion in Simplicial Quantum Gravity
We construct the strong-coupling series in 4d simplicial quantum gravity up
to volume 38. It is used to calculate estimates for the string susceptibility
exponent gamma for various modifications of the theory. It provides a very
efficient way to get a first view of the phase structure of the models.Comment: LATTICE98(surfaces), 3 pages, 4 eps figure
From simple to complex networks: inherent structures, barriers and valleys in the context of spin glasses
Given discrete degrees of freedom (spins) on a graph interacting via an
energy function, what can be said about the energy local minima and associated
inherent structures? Using the lid algorithm in the context of a spin glass
energy function, we investigate the properties of the energy landscape for a
variety of graph topologies. First, we find that the multiplicity Ns of the
inherent structures generically has a lognormal distribution. In addition, the
large volume limit of ln/ differs from unity, except for the
Sherrington-Kirkpatrick model. Second, we find simple scaling laws for the
growth of the height of the energy barrier between the two degenerate ground
states and the size of the associated valleys. For finite connectivity models,
changing the topology of the underlying graph does not modify qualitatively the
energy landscape, but at the quantitative level the models can differ
substantially.Comment: 10 pages, 9 figs, slightly improved presentation, more references,
accepted for publication in Phys Rev
Coherence and Decoherence in Radiation off Colliding Heavy Ions
We discuss the kinetics of a disoriented chiral condensate, treated as an
open quantum system. We suggest that the problem is analogous to that of a
damped harmonic oscillator. Master equations are used to establish a hierarchy
of relevant time scales. Some phenomenological consequences are briefly
outlined.Comment: 15 latex pages, LPTHE Orsay 93/19, e-mail: [email protected]
Energy consumption and capacity utilization of galvanizing furnaces
An explicit equation leading to a method for improving furnace efficiency is presented. This equation is dimensionless and can be applied to furnaces of any size and fuel type for the purposes of comparison. The implications for current furnace design are discussed. Currently the technique most commonly used to reduce energy consumption in galvanizing furnaces is to increase burner turndown. This is shown by the analysis presented here actually to worsen the thermal efficiency of the furnace, particularly at low levels of capacity utilization. Galvanizing furnaces are different to many furnaces used within industry, as a quantity of material (in this case zinc) is kept molten within the furnace at all times, even outside production periods. The dimensionless analysis can, however, be applied to furnaces with the same operational function as a galvanizing furnace, such as some furnaces utilized within the glass industry. © IMechE 2004
On the microscopic dynamics of DCC formation
The dynamics of the pion field after a quench is studied in the framework of
the linear sigma model. Our aim is to determine to what extent the amplified
pion field resembles the DCC picture originally proposed in the early '90s. We
present the result of a computer experiment where, among other things, we study
in detail the correlation between isospin orientations of the distinct modes of
the field. We show that this correlation is absent. In a sense, the distinct
modes behave as distinct DCCs. The implications of this observation are
discussed.Comment: 19 pages, Latex2e, 7 figures in EPS, uses (included) boldgreek.sty
and standard epsf package
Domains of Disoriented Chiral Condensate
The probability distribution of neutral pion fraction from independent
domains of disoriented chiral condensate is characterized. The signal for the
condensate is clear for a small number of domains but is greatly reduced for
more than three.Comment: revtex, 2 postscript figures, submitted to Phys.Rev.
Tree Networks with Causal Structure
Geometry of networks endowed with a causal structure is discussed using the
conventional framework of equilibrium statistical mechanics. The popular
growing network models appear as particular causal models. We focus on a class
of tree graphs, an analytically solvable case. General formulae are derived,
describing the degree distribution, the ancestor-descendant correlation and the
probability a randomly chosen node lives at a given geodesic distance from the
root. It is shown that the Hausdorff dimension of the causal networks is
generically infinite, in contrast to the maximally random trees, where it is
generically finite.Comment: 9 pages, 2-column revtex format, 1 eps figure, misprints correcte
Centauro- and anti-Centauro-type events
Assuming that leading particles in high-energy hadronic and nuclear
collisions become sources of a classical pion field, we show that the direct
production of pions favors Centauro (mainly charged) events and that the
production of pions through the -type channel favors anti-Centauro
(mainly neutral) events. We also observe a strong negative neutral-charged
correlation in both cases.Comment: 14 pages, 2 pictures, late
Can pions created in high-energy heavy-ion collisions produce a Centauro-type effect?
We study a Centauro-type phenomenon in high-energy heavy-ion collisions by
assuming that pions are produced semiclassically both directly and in pairs
through the isovector channel. The leading-particle effect and the
factorization property of the scattering amplitude in the impact-parameter
space are used to define the classical pion field. By analyzing the joint
probability function for producing neutral
and negative pions from a definite isospin state of the
incoming leading-particle system we show that only direct production of pions
without isovector pairs favors Centauro-type behavior. The presence of
isovector pairs seems to destroy the effect. Our conclusion is supported
through the calculation of two pion correlation parameters, and
, and the average number of neutral pions as
a function of negative pions produced.Comment: 12 pages, 3 pictures, late
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