135 research outputs found
Decoherence Functional and Inhomogeneities in the Early Universe
We investigate the quantum to classical transition of small inhomogeneous
fluctuations in the early Universe using the decoherence functional of
Gell-Mann and Hartle. We study two types of coarse graining; one due to coarse
graining the value of the scalar field and the other due to summing over an
environment. We compare the results with a previous study using an environment
and the off-diagonal rule proposed by Zurek. We show that the two methods give
different results.Comment: 15 pages in plain te
Comparison of Field Theory Models of Interest Rates with Market Data
We calibrate and test various variants of field theory models of the interest
rate with data from eurodollars futures. A model based on a simple
psychological factor are seen to provide the best fit to the market. We make a
model independent determination of the volatility function of the forward rates
from market data.Comment: 9 figure
Entropy and Uncertainty of Squeezed Quantum Open Systems
We define the entropy S and uncertainty function of a squeezed system interacting with a thermal bath, and study how they change in time by following the evolution of the reduced density matrix in the influence functional formalism. As examples, we calculate the entropy of two exactly solvable squeezed systems: an inverted harmonic oscillator and a scalar field mode evolving in an inflationary universe. For the inverted oscillator with weak coupling to the bath, at both high and low temperatures, , where r is the squeeze parameter. In the de Sitter case, at high temperatures, where , being the coupling to the bath and H the Hubble constant. These three cases confirm previous results based on more ad hoc prescriptions for calculating entropy. But at low temperatures, the de Sitter entropy is noticeably different. This result obtained from a more rigorous approach, shows that factors usually ignored by the conventional approaches, i.e., the nature of the environment and the coupling strength betwen the system and the environment, are important
Option Pricing from Wavelet-Filtered Financial Series
We perform wavelet decomposition of high frequency financial time series into
large and small time scale components. Taking the FTSE100 index as a case
study, and working with the Haar basis, it turns out that the small scale
component defined by most ( 99.6%) of the wavelet coefficients can be
neglected for the purpose of option premium evaluation. The relevance of the
hugely compressed information provided by low-pass wavelet-filtering is related
to the fact that the non-gaussian statistical structure of the original
financial time series is essentially preserved for expiration times which are
larger than just one trading day.Comment: 4 pages, 1 figur
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