14,203 research outputs found
The Feynman-Wilson gas and the Lund model
We derive a partition function for the Lund fragmentation model and compare
it with that of a classical gas. For a fixed rapidity ``volume'' this partition
function corresponds to a multiplicity distribution which is very close to a
binomial distribution. We compare our results with the multiplicity
distributions obtained from the JETSET Monte Carlo for several scenarios.
Firstly, for the fragmentation vertices of the Lund string. Secondly, for the
final state particles both with and without decays.Comment: Latex, 21+1 pages, 11 figure
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Black and Asian police officers and support staff: prejudice, identity, agency and social cohesion
This primary research paper presents a review of research that finds that the British Government’s new social cohesion agenda does hold promise for racial and ethnic prejudice reduction – but that social cohesion policies and practice must include at their core policies to reduce institutional racism in British police services. Analysis of the literature reveals that considerably more research is required to examine the precise nature and dynamics of institutional racism within the police services. There is a need to understand how racism against Black and minority ethnic (BME) police employees, and police racism against BME communities, influences social cohesion. That this is important, given the British government’s current social cohesion policy agenda, is patently clear. Considerably more research is about to be undertaken in this area by the authors of this paper and the results will be published in the academic press, disseminated at conferences and presented in training programmes
Evolution of the Pairwise Peculiar Velocity Distribution Function in Lagrangian Perturbation Theory
The statistical distribution of the radial pairwise peculiar velocity of
galaxies is known to have an exponential form as implied by observations and
explicitly shown in N-body simulations. Here we calculate its statistical
distribution function using the Zel'dovich approximation assuming that the
primordial density fluctuations are Gaussian distributed. We show that the
exponential distribution is realized as a transient phenomena on megaparsec
scales in the standard cold-dark-matter model.Comment: 19 pages, 8 Postscript figures, AAS LaTe
Documentation of Apollo 15 samples
A catalog is presented of the documentation of Apollo 15 samples using photographs and verbal descriptions returned from the lunar surface. Almost all of the Apollo 15 samples were correlated with lunar surface photographs, descriptions, and traverse locations. Where possible, the lunar orientations of rock samples were reconstructed in the lunar receiving laboratory, using a collimated light source to reproduce illumination and shadow characteristics of the same samples shown in lunar photographs. In several cases, samples were not recognized in lunar surface photographs, and their approximate locations are known only by association with numbered sample bags used during their collection. Tables, photographs, and maps included in this report are designed to aid in the understanding of the lunar setting of the Apollo 15 samples
Nonlinear Transport through NS Junctions due to Imperfect Andreev Reflection
We investigate a normal metal -- superconductor (point) contact in the limit
where the number of conducting channels in the metallic wire is reduced to few
channels. As the effective Fermi energy drops below the gap energy, a
conducting band with a width twice the Fermi energy is formed. Depending on the
mode of operation, the conduction band can be further squeezed, leading to
various non-linear effects in the current-voltage characteristics such as
current saturation, a N-shaped negative differential resistance, bistability,
and hysteresis.Comment: 4 pages, RevTeX, three postscript figure
Josephson Coupling through a Quantum Dot
We derive, via fourth order perturbation theory, an expression for the
Josephson current through a gated interacting quantum dot. We analyze our
expression for two different models of the superconductor-dot-superconductor
(SDS) system. When the matrix elements connecting dot and leads are featureless
constants, we compute the Josephson coupling J_c as a function of the gate
voltage and Coulomb interaction. In the diffusive dot limit, we compute the
probability distribution P(J_c) of Josephson couplings. In both cases, pi
junction behavior (J_c < 0) is possible, and is not simply dependent on the
parity of the dot occupancy.Comment: 9 pages; 3 encapsulated PostScript figure
Is there screwiness at the end of the QCD cascades?
We discuss what happens at the end of the QCD cascades. We show that, with
just a few reasonable assumptions, the emission of soft gluons is constrained
to produce an ordered field in the form of a helix. We describe how to modify
the Lund fragmentation scheme in order to fragment such a field. Our modified
fragmentation scheme yields results which are consistent with current
experimental measurements, but predicts at least one signature which should be
observable.Comment: 21+1 page
Temperature dependence of surface reconstructions of Au on Pd(110)
Surface reconstructions of Au film on Pd(110) substrate are studied using a
local Einstein approximation to quasiharmonic theory with the Sutton-Chen
interatomic potential. Temperature dependent surface free energies for
different coverages and surface structures are calculated. Experimentally
observed transformations from to and
structures can be explained in the framework of this model. Also conditions for
Stranski-Krastanov growth mode are found to comply with experiments. The domain
of validity of the model neglecting mixing entropy is analyzed.Comment: 7 pages, REVTeX two-column format, 3 postscript figures available on
request from [email protected] To appear in Phys. Rev. Letter
Preliminary catalog of pictures taken on the lunar surface during the Apollo 15 mission
Catalog of all pictures taken from lunar module or lunar surface during Apollo 15 missio
A Longitudinal perspective on the social and economic characteristics of the U.S. Gulf of Mexico Charter and Party Boat Industry
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