200,781 research outputs found
Study of the Wealth Inequality in the Minority Game
To demonstrate the usefulness of physical approaches for the study of
realistic economic systems, we investigate the inequality of players' wealth in
one of the most extensively studied econophysical models, namely, the minority
game (MG). We gauge the wealth inequality of players in the MG by a well-known
measure in economics known as the modified Gini index. From our numerical
results, we conclude that the wealth inequality in the MG is very severe near
the point of maximum cooperation among players, where the diversity of the
strategy space is approximately equal to the number of strategies at play. In
other words, the optimal cooperation between players comes hand in hand with
severe wealth inequality. We also show that our numerical results in the
asymmetric phase of the MG can be reproduced semi-analytically using a replica
method.Comment: 9 pages in revtex 4 style with 3 figures; minor revision with a
change of title; to appear in PR
The Angular Momentum Distribution within Halos in Different Dark Matter Models
We study the angular momentum profile of dark matter halos for a statistical
sample drawn from a set of high-resolution cosmological simulations of
particles. Two typical Cold Dark Matter (CDM) models have been analyzed, and
the halos are selected to have at least particles in order to
reliably measure the angular momentum profile. In contrast with the recent
claims of Bullock et al., we find that the degree of misalignment of angular
momentum within a halo is very high. About 50 percent of halos have more than
10 percent of halo mass in the mass of negative angular momentum . After the
mass of negative is excluded, the cumulative mass function follows
approximately the universal function proposed by Bullock et al., though we
still find a significant fraction of halos () which exhibit
systematic deviations from the universal function. Our results, however, are
broadly in good agreement with a recent work of van den Bosch et al.. We also
study the angular momentum profile of halos in a Warm Dark Matter (WDM) model
and a Self-Interacting Dark Matter (SIDM) model. We find that the angular
momentum profile of halos in the WDM is statistically indistinguishable from
that in the CDM model, but the angular momentum of halos in the SIDM is reduced
by the self-interaction of dark matter.Comment: 23 pages, 10 figures, 2 tables. Revised version, added a new table,
accepted for publication in MNRA
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Chinese peasant entrepreneurs: an examination of township and village
One of the greatest achievements in China's economic reform is the development of rural township and village enterprises (TVEs). Their importance in the national economy can be seen from the fact that by the end of 1993, TVEs accounted for nearly one third of the agricultural labour force, and one fifth of the total labour force nationwide. Despite some research attention being given to Chinese TVEs, the peasant entrepreneurs, owners and /or managers of these enterprises have remained largely unknown in the West. Who are they? Where are they from? What are their unique characteristics which distinguish them from both managers in the state-owned Chinese enterprises (SOEs) and small business owners /entrepreneurs in the West? What environmental factors contribute to the shaping of these characteristics? What are the problems faced by them and the possible solutions? This paper addresses these questions
Subtraction method for NLO corrections in Monte-Carlo event generators for Z boson production
We use a subtraction method to construct NLO corrections in a Monte-Carlo
event generator for the case of vector boson production in Drell-Yan processes.
Our calculations are carried out both for the Bengtsson-Sjostrand-van Zijl
(BSZ) algorithm and for a modified algorithm proposed by Collins. In the case
of the modified algorithm, we compute the relation between the parton
distribution functions and the ones in the MSbar scheme; this relation is the
same as the corresponding relation for DIS. For the BSZ algorithm, we show that
there is no simple relation.Comment: 16 pages, 4 figures, JHEP class. Misprints correcte
Decay rate of a Wannier exciton in low dimensional systems
The superradiant decay rate of Wannier exciton in one dimensional system is
studied. The crossover behavior from 1D chain to 2D film is also examined. It
is found that the decay rate shows oscillatory dependence on channel width L.
When the quasi 1-D channel is embeded with planar microcavities, it is shown
that the dark mode exciton can be examined experimentally.Comment: 12 pages, 1 figur
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