1,981 research outputs found
The principle of symmetric bracket invariance as the origin of first and second quantization
The principle of invariance of the c-number symmetric bracket is used to
derive both the quantum operator commutator relation
and the time-dependent Schr\"odinger equation. A c-number dynamical equation is
found which leads to the second quantized field theory of bosons and fermions.Comment: 14 pages. Contributed Paper: XIX International Symposium on Lepton
and Photon Interactions at High Energies, Stanford University, August 9-14,
199
Non-grassmann "classicization" of fermion dynamics
A carefully motivated symmetric variant of the Poisson bracket in ordinary (not Grassmann) phase space variables is shown to satisfy identities which are in algebraic correspondence with the anticommutation postulates for quantized Fermion systems. "Symplecticity" in terms of this symmetric Poisson bracket implies generalized Hamilton's equations that can only be of Schroedinger type (e.g., the Dirac equation but not the Klein-Gordon or Maxwell equations). This restriction also excludes the old "four-Fermion" theory of beta decay
Large scale bias and the peak background split
Dark matter haloes are biased tracers of the underlying dark matter
distribution. We use a simple model to provide a relation between the abundance
of dark matter haloes and their spatial distribution on large scales. Our model
shows that knowledge of the unconditional mass function alone is sufficient to
provide an accurate estimate of the large scale bias factor. Then we use the
mass function measured in numerical simulations of SCDM, OCDM and LCDM to
compute this bias. Comparison with these simulations shows that this simple way
of estimating the bias relation and its evolution is accurate for less massive
haloes as well as massive ones. In particular, we show that haloes which are
less/more massive than typical M* haloes at the time they form are more/less
strongly clustered than formulae based on the standard Press-Schechter mass
function predict.Comment: 8 pages, 6 figures, submitted to MNRAS corrected y-label for fig.4
(newlabel = 1 + oldlabel
NIR Luminosity Function of Galaxies in Close Major-Merger Pairs and Mass Dependence of Merger Rate
A sample of close major-merger pairs (projected separation kpc, band magnitude difference mag) is selected from the matched 2MASS-2dFGRS catalog of Cole et al.
(2001). The pair primaries are brighter than mag. After
corrections for various biases, the comparison between counts in the paired
galaxy sample and counts in the parent sample shows that for the local `M*
galaxies' sampled by flux limited surveys, the fraction of galaxies in the
close major-merger pairs is 1.70. Using 38 paired galaxies in the
sample, a band luminosity function (LF) is calculated. This is the
first unbiased LF for a sample of objectively defined interacting/merging
galaxies in the local universe, while all previously determined LFs of paired
galaxies are biased by mistreating paired galaxies as singles. A stellar mass
function (MF) is translated from the LF. Compared to the LF/MF of 2MASS
galaxies, a differential pair fraction function is derived. The results suggest
a trend in the sense that less massive galaxies may have lower chance to be
involved in close major-merger pairs than more massive galaxies. The algorithm
presented in this paper can be easily applied to much larger samples of 2MASS
galaxies with redshifts in near future.Comment: Accepted by ApJL, 16 pages, 2 figure
Collisional effects on global gyrokinetic particle-in-cell simulations of ITG and TEM instabilities in tokamaks
The environmental dependence of clustering in hierarchical models
In hierarchical models, density fluctuations on different scales are
correlated. This induces correlations between dark halo masses, their formation
histories, and their larger-scale environments. In turn, this produces a
correlation between galaxy properties and environment. This correlation is
entirely statistical in nature. We show how the observed clustering of galaxies
can be used to quantify the importance of this statistical correlation relative
to other physical effects which may also give rise to correlations between the
properties of galaxies and their surroundings. We also develop a halo model
description of this environmental dependence of clustering.Comment: 11 pages, 6 figures, MNRAS in pres
An integrated response to risks of violence against bus drivers:When on-board assaults affect safety on our roads
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