134 research outputs found
Monetary economics from econophysics perspective
This is an invited article for the Discussion and Debate special issue of The
European Physical Journal Special Topics on the subject "Can Economics Be a
Physical Science?" The first part of the paper traces the personal path of the
author from theoretical physics to economics. It briefly summarizes
applications of statistical physics to monetary transactions in an ensemble of
economic agents. It shows how a highly unequal probability distribution of
money emerges due to irreversible increase of entropy in the system. The second
part examines deep conceptual and controversial issues and fallacies in
monetary economics from econophysics perspective. These issues include the
nature of money, conservation (or not) of money, distinctions between money vs.
wealth and money vs. debt, creation of money by the state and debt by the
banks, the origins of monetary crises and capitalist profit. Presentation uses
plain language understandable to laypeople and may be of interest to both
specialists and general public.Comment: 23 pages, 1 figur
Econophysics, Statistical Mechanics Approach to
This is a review article for Encyclopedia of Complexity and System Science,
to be published by Springer http://refworks.springer.com/complexity/. The paper
reviews statistical models for money, wealth, and income distributions
developed in the econophysics literature since late 1990s.Comment: 24 pages, 11 figures, 151 citations. V.2: one reference added. V.3:
many minor corrections, some references added. V.4: many minor stylistic
corrections incorporated after receiving the proof
Hopf invariant for long-wavelength skyrmions in quantum Hall systems for integer and fractional fillings
We show that a Hopf term exists in the effective action of long-wavelength
skyrmions in quantum Hall systems for both odd integer and fractional filling
factors , where is an integer. We evaluate the prefactor
of the Hopf term using Green function method in the limit of strong external
magnetic field using model of local interaction. The prefactor () of the
Hopf term is found to be equal to . The spin and charge densities and
hence the total spin and charge of the skyrmion are computed from the effective
action. The total spin is found to have a dominant contribution from the Berry
term in the effective action and to increase with the size of the skyrmion. The
charge and the statistics of the skyrmion, on the other hand, are completely
determined by the prefactor of the Hopf term. Consequently, the skyrmions have
charge and are Fermions (anyons) for odd integer (fractional) fillings.
We also obtain the effective action of the skyrmions at finite temperature. It
is shown that at finite temperature, the value of the prefactor of the Hopf
term depends on the order in which the zero-momentum and zero-frequency limits
are taken.Comment: Replaced with revised versio
Evidence for the exponential distribution of income in the USA
Using tax and census data, we demonstrate that the distribution of individual
income in the USA is exponential. Our calculated Lorenz curve without fitting
parameters and Gini coefficient 1/2 agree well with the data. From the
individual income distribution, we derive the distribution function of income
for families with two earners and show that it also agrees well with the data.
The family data for the period 1947-1994 fit the Lorenz curve and Gini
coefficient 3/8=0.375 calculated for two-earners families.Comment: 4 pages, including 5 figures. Uses Springer Verlag style classes for
Eur. Phys. J. B (included). Submitted to the proceedings of APFA2 conference.
V.2: minor stylistic improvement
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