11,740 research outputs found
Markov Properties of Electrical Discharge Current Fluctuations in Plasma
Using the Markovian method, we study the stochastic nature of electrical
discharge current fluctuations in the Helium plasma. Sinusoidal trends are
extracted from the data set by the Fourier-Detrended Fluctuation analysis and
consequently cleaned data is retrieved. We determine the Markov time scale of
the detrended data set by using likelihood analysis. We also estimate the
Kramers-Moyal's coefficients of the discharge current fluctuations and derive
the corresponding Fokker-Planck equation. In addition, the obtained Langevin
equation enables us to reconstruct discharge time series with similar
statistical properties compared with the observed in the experiment. We also
provide an exact decomposition of temporal correlation function by using
Kramers-Moyal's coefficients. We show that for the stationary time series, the
two point temporal correlation function has an exponential decaying behavior
with a characteristic correlation time scale. Our results confirm that, there
is no definite relation between correlation and Markov time scales. However
both of them behave as monotonic increasing function of discharge current
intensity. Finally to complete our analysis, the multifractal behavior of
reconstructed time series using its Keramers-Moyal's coefficients and original
data set are investigated. Extended self similarity analysis demonstrates that
fluctuations in our experimental setup deviates from Kolmogorov (K41) theory
for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references,
figures and major correction
Logarithmic two dimensional spin-1/3 fractional supersymmetric conformal field theories and the two point functions
Logarithmic spin-1/3 superconformal field theories are investigated. the
chiral and full two-point functions of two-(or more-) dimensional Jordanian
blocks of arbitrary weights, are obtained.Comment: 7 pages, Latex, no figure
Logarithmic conformal field theories with continuous weights
We study the logarithmic conformal field theories in which conformal weights
are continuous subset of real numbers. A general relation between the
correlators consisting of logarithmic fields and those consisting of ordinary
conformal fields is investigated. As an example the correlators of the
Coulomb-gas model are explicitly studied.Comment: Latex, 12 pages, IPM preprint, to appear in Phys. Lett.
Zamalodchikov's C-Theorem and The Logarithmic Conformal Field Theory
We consider perturbation of a conformal field theory by a pair of relevant
logarithmic operators and calculate the beta function up to two loops. We
observe that the beta function can not be derived from a potential. Thus the
renormalization group trajectories are not always along decreasing values of
the central charge. However there exists a domain of structure constants in
which the c-theorem still holds.Comment: 10 pages, latex, no figures, some references are added, The role of
coefficients of the OPE in LCFT on the beta-functions are disscuse
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