213 research outputs found
Spectroscopy, Equation Of State And Monopole Percolation In Lattice QED With Two Flavors
Non-compact lattice QED with two flavors of light dynamical quarks is
simulated on lattices, and the chiral condensate, monopole density and
susceptibility and the meson masses are measured. Data from relatively high
statistics runs at relatively small bare fermion masses of 0.005, 0.01, 0.02
and 0.03 (lattice units) are presented. Three independent methods of data
analysis indicate that the critical point occurs at and that
the monopole condensation and chiral symmetry breaking transitions are
coincident. The monopole condensation data satisfies finite size scaling
hypotheses with critical indices compatible with four dimensional percolation.
The best chiral equation of state fit produces critical exponents
(, ) which deviate significantly from mean
field expectations. Data for the ratio of the sigma to pion masses produces an
estimate of the critical index in good agreement with chiral
condensate measurements. In the strong coupling phase the ratio of the meson
masses are ,
and , while on the weak coupling side of the
transition , ,
indicating the restoration of chiral symmetry.\footnote{\,^{}}{August 1992}Comment: 21 pages, 24 figures (not included
The Block Spin Renormalization Group Approach and Two-Dimensional Quantum Gravity
A block spin renormalization group approach is proposed for the dynamical
triangulation formulation of two-dimensional quantum gravity. The idea is to
update link flips on the block lattice in response to link flips on the
original lattice. Just as the connectivity of the original lattice is meant to
be a lattice representation of the metric, the block links are determined in
such a way that the connectivity of the block lattice represents a block
metric. As an illustration, this approach is applied to the Ising model coupled
to two-dimensional quantum gravity. The correct critical coupling is
reproduced, but the critical exponent is obscured by unusually large finite
size effects.Comment: 10 page
Investigation of Cyclic Liquefaction with Discrete Element Simulations
A discrete-element method (DEM) assembly of virtual particles is calibrated to approximate the behavior of a natural sand in undrained loading. The particles are octahedral, bumpy clusters of spheres that are compacted into assemblies of different densities. The contact modelis a Jäger generalization of the Hertz contact, which yields a small-strain shear modulus that is proportional to the square root of confining stress. Simulations made of triaxial extension and compression loading conditions and of simple shear produce behaviors that are similar to sand. Undrained cyclic shearing simulations are performed with nonuniform amplitudes of shearing pulses and with 24 irregular seismic shearing sequences. A methodology is proposed for quantifying the severities of such irregular shearing records, allowing the 24 sequences to be ranked in severity. The relative severities of the 24 seismic sequences show an anomalous dependence on sampling density. Four scalar measures are proposed for predicting the severity of a particular loading sequence. A stress-based scalar measure shows superior efficiency in predicting initial liquefaction and pore pressure rise
Catalyst development for the selective methylation of catechol
Gas-phase alkylation of catechol with methanol on g-alumina and modified g-alumina catalysts is studied exptl. By limiting the conversion of X < 0.3, the formation of polymethylated species can be avoided and only the three isomers guaiacol, 3-methylcatechol and 4-methylcatechol are obsd. Optimizing the catalyst compn. and the reaction conditions, a selectivity of 0.75 for the industrially most valuable product 3-methylcatechol can be obtained. [on SciFinder (R)
QCD Thermodynamics at and 12
We present results from studies of high temperature QCD with two flavors of
Kogut-Susskind quarks on lattices at a quark mass of
and on lattices at quark masses and
0.016. The value of the crossover temperature is consistent with that obtained
on coarser lattices and/or at larger quark masses. Results are presented for
the chiral order parameter and for the baryon number susceptibility.Comment: 3-pages, uuencoded compressed postscript file, contribution to
Lattice'94 conferenc
Folding transition of the triangular lattice in a discrete three--dimensional space
A vertex model introduced by M. Bowick, P. Di Francesco, O. Golinelli, and E.
Guitter (cond-mat/9502063) describing the folding of the triangular lattice
onto the face centered cubic lattice has been studied in the hexagon
approximation of the cluster variation method. The model describes the
behaviour of a polymerized membrane in a discrete three--dimensional space. We
have introduced a curvature energy and a symmetry breaking field and studied
the phase diagram of the resulting model. By varying the curvature energy
parameter, a first-order transition has been found between a flat and a folded
phase for any value of the symmetry breaking field.Comment: 11 pages, latex file, 2 postscript figure
Dealing with consumer differences in liking during repeated exposure to food; typical dynamics in rating behavior
Consumers show high interindividual variability in food liking during repeated exposure. To investigate consumer liking during repeated exposure, data is often interpreted on a product level by averaging results over all consumers. However, a single product may elicit inconsistent behaviors in consumers; averaging will mix and hide possible subgroups of consumer behaviors, leading to a misinterpretation of the results. To deal with the variability in consumer liking, we propose to use clustering on data from consumer-product combinations to investigate the nature of the behavioral differences within the complete dataset. The resulting behavioral clusters can then be used to describe product acceptance. To test this approach we used two independent data sets in which young adults were repeatedly exposed to drinks and snacks, respectively. We found that five typical consumer behaviors existed in both datasets. These behaviors differed both in the average level of liking as well as its temporal dynamics. By investigating the distribution of a single product across typical consumer behaviors, we provide more precise insight in how consumers divide in subgroups based on their product liking (i.e. product modality). This work shows that taking into account and using interindividual differences can unveil information about product acceptance that would otherwise be ignored
The Effective Lagrangian of the Two Higgs Doublet Model
We consider the two Higgs doublet model extension of the Standard Model in
the limit where all physical scalar particles are very heavy; too heavy, in
fact, to be experimentally produced in forthcoming experiments. The symmetry
breaking sector can thus be described by an effective chiral Lagrangian. We
obtain the values of the coefficients of the O(p^4) operators relevant to the
oblique corrections and investigate to what extent some non-decoupling effects
may remain at low energies.Comment: 16 pages, LaTeX, 2 figure
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