9,998 research outputs found
Novel Scaling Behavior for the Multiplicity Distribution under Second-Order Quark-Hadron Phase Transition
Deviation of the multiplicity distribution in small bin from its
Poisson counterpart is studied within the Ginzburg-Landau description for
second-order quark-hadron phase transition. Dynamical factor for the distribution and ratio are defined, and
novel scaling behaviors between are found which can be used to detect the
formation of quark-gluon plasma. The study of and is also very
interesting for other multiparticle production processes without phase
transition.Comment: 4 pages in revtex, 5 figures in eps format, will be appeared in Phys.
Rev.
Anomalous scaling and Lee-Yang zeroes in Self-Organized Criticality
We show that the generating functions of avalanche observables in SOC models
exhibits a Lee-Yang phenomenon. This establishes a new link between the
classical theory of critical phenomena and SOC. A scaling theory of the
Lee-Yang zeroes is proposed including finite sampling effects.Comment: 33 pages, 19 figures, submitte
Scaling in the Lattice Gas Model
A good quality scaling of the cluster size distributions is obtained for the
Lattice Gas Model using the Fisher's ansatz for the scaling function. This
scaling identifies a pseudo-critical line in the phase diagram of the model
that spans the whole (subcritical to supercritical) density range. The
independent cluster hypothesis of the Fisher approach is shown to describe
correctly the thermodynamics of the lattice only far away from the critical
point.Comment: 4 pages, 3 figure
Star formation histories and evolution of 35 brightest E+A galaxies from SDSS DR5
We pick out the 35 brightest galaxies from Goto's E+A galaxies catalogue
which are selected from the Sloan Digital Sky Survey Data Release 5. The
spectra of E+As are prominently characterized by the strong Balmer absorption
lines but little [Oii] or H_alpha emission lines. In this work we study the
stellar populations of the sample galaxies by fitting their spectra using
ULySS, which is a robust full spectrum fitting method. We fit each of the
sample with 1-population (a single stellar population-a SSP) and 3-population
(3 SSPs) models, separately. By 1-population fits, we obtain SSP-equivalent
ages and metallicities which correspond to the `luminosity-weighted' averages.
By 3-population fits, we divide components into three groups in age (old
stellar population-OSP, intermediate-age stellar population-ISP, and young
stellar population-YSP), and then get the optimal age, metallicity and
population fractions in both mass and light for OSP, ISP and YSP. During the
fits, both Pegase.HR/Elodie3.1 and Vazdekis/Miles are used as two independent
population models. The two models result in generally consistent conclusions as
follows: for all the sample galaxies, YSPs (< 1Gyr) make important
contributions to the light. However, the dominant contributors to mass are
OSPs. We also reconstruct the smoothing star formation histories (SFHs) by
giving star formation rate (SFR) versus evolutionary age. In addition, we fit
the E+A sample and 34 randomly selected elliptical galaxies with 2-population
(2 SSPs) model. We obtain the equivalent age of old components for each of the
E+A sample and elliptical galaxies. By comparison, the old components of E+As
are statistically much younger than those of ellipticals. From the standpoint
of the stellar population age, this probably provides an evidence for the
proposed evolutionary link from E+As to early-types (E/S0s).Comment: 16 pages, 9 figures, Accepted for publication on MNRA
Topology of event distribution as a generalized definition of phase transitions in finite systems
We propose a definition of phase transitions in finite systems based on
topology anomalies of the event distribution in the space of observations. This
generalizes all the definitions based on the curvature anomalies of
thermodynamical potentials and provides a natural definition of order
parameters. The proposed definition is directly operational from the
experimental point of view. It allows to study phase transitions in Gibbs
equilibria as well as in other ensembles such as the Tsallis ensemble.Comment: 4 pages, 3 figure
Symmetries of Large N Matrix Models for Closed Strings
We obtain the symmetry algebra of multi-matrix models in the planar large N
limit. We use this algebra to associate these matrix models with quantum spin
chains. In particular, certain multi-matrix models are exactly solved by using
known results of solvable spin chain systems.Comment: 12 pages, 1 eps figure, RevTex, some minor typos in the publised
version are correcte
Scaling of Aharonov-Bohm couplings and the dynamical vacuum in gauge theories
Recent results on the vacuum polarization induced by a thin string of
magnetic flux lead us to suggest an analogue of the Copenhagen `flux spaghetti'
QCD vacuum as a possible mechanism for avoiding the divergence of perturbative
QED, thus permitting consistent completion of the full, nonperturbative theory.
The mechanism appears to operate for spinor, but not scalar, QED.Comment: 11 pages, ITP-SB-92-40, (major conceptual evolution from original
Proximity of Iron Pnictide Superconductors to a Quantum Tricritical Point
We determine the nature of the magnetic quantum critical point in the doped
LaFeAsO using a set of constrained density functional calculations that provide
ab initio coefficients for a Landau order parameter analysis. The system turns
out to be remarkably close to a quantum tricritical point, where the nature of
the phase transition changes from first to second order. We compare with the
effective field theory and discuss the experimental consequences.Comment: 4 pages, 4 figure
Franck-Condon Effect in Central Spin System
We study the quantum transitions of a central spin surrounded by a
collective-spin environment. It is found that the influence of the
environmental spins on the absorption spectrum of the central spin can be
explained with the analog of the Franck-Condon (FC) effect in conventional
electron-phonon interaction system. Here, the collective spins of the
environment behave as the vibrational mode, which makes the electron to be
transitioned mainly with the so-called "vertical transitions" in the
conventional FC effect. The "vertical transition" for the central spin in the
spin environment manifests as, the certain collective spin states of the
environment is favored, which corresponds to the minimal change in the average
of the total spin angular momentum.Comment: 8 pages, 8 figure
Three-dimensional CFD simulations with large displacement of the geometries using a connectivity-change moving mesh approach
This paper deals with three-dimensional (3D) numerical simulations involving 3D moving geometries with large displacements on unstructured meshes. Such simulations are of great value to industry, but remain very time-consuming. A robust moving mesh algorithm coupling an elasticity-like mesh deformation solution and mesh optimizations was proposed in previous works, which removes the need for global remeshing when performing large displacements. The optimizations, and in particular generalized edge/face swapping, preserve the initial quality of the mesh throughout the simulation. We propose to integrate an Arbitrary Lagrangian Eulerian compressible flow solver into this process to demonstrate its capabilities in a full CFD computation context. This solver relies on a local enforcement of the discrete geometric conservation law to preserve the order of accuracy of the time integration. The displacement of the geometries is either imposed, or driven by fluid–structure interaction (FSI). In the latter case, the six degrees of freedom approach for rigid bodies is considered. Finally, several 3D imposed-motion and FSI examples are given to validate the proposed approach, both in academic and industrial configurations
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