1,152,411 research outputs found
Design and Analysis of low coupling, high transmission optical wavelength Demultiplexer based on two dimensional photonic crystal
In this work, design and simulation of two dimensional photonic crystal with hexagonal lattice based wavelength division multiplexer is investigated. It is consists of high dielectric rods of GaAs with refractive index 3.375, surrounded by air. This device is ultra compact. The demultiplexing of wavelengths 1330nm and 1470nm is done, based on different output line defects with different radius by pitch ratio. The Discrete Fourier Transforms and power spectrum is obtained using OptiFDTD method and results are compared for various wavelengths
Effects to Scalar Meson Decays of Strong Mixing between Low and High Mass Scalar Mesons
We analyze the mass spectroscopy of low and high mass scalar mesons and get
the result that the coupling strengths of the mixing between low and high mass
scalar mesons are very strong and the strengths of mixing for scalar
mesons and those of I=0 scalar mesons are almost same. Next, we analyze the
decay widths and decay ratios of these mesons and get the results that the
coupling constants for which represents the coupling of high
mass scalar meson -> two pseudoscalar mesons are almost same as the
coupling for the I=0. On the other hand, the coupling constant for
which represents the low mass scalar meson -> are far
from the coupling constant for I=0. We consider a resolution for this
discrepancy. Coupling constant for glueball -> is smaller than
the coupling . is .Comment: 15 pages, 6 figure
The strong coupling constant at large distances
In this paper we discuss effective strong coupling constants. Those are well
behaved in the low-Q^2 domain, contrarily to alpha_s from pQCD. We present an
extraction of an effective strong coupling constant from Jefferson Lab
polarized data at intermediate and low Q^2. We also show how these data,
together with spin sum rules, allow us to obtain the effective coupling
constant over the entire Q^2 range. We then discuss the relation between the
experimentally extracted coupling constant and theoretical calculations at low
Q^2. We conclude on the importance of such study for the application of the
AdS/CFT correspondence to QCD.Comment: Proceedings for Spin2008 symposium. v2: added 2 referecences re.
infrared fixed poin
Double expansion in asymptotically free theories
I propose an approximation scheme for asymptotically free field theories
combining both weak coupling and strong coupling series. The weak coupling
expansion is used to integrate the high frequency modes and the resulting low
energy effective theory is solved using the strong coupling expansion. In some
models there exists an intermediate scale at which both expansions make sense.
The method is tested on few low dimensional models for which an exact solution
is known.Comment: 15 pages, written in LaTeX, figures generated using FEYNMANN are
commented and can be obtained upon request
Frequency behavior of Raman coupling coefficient in glasses
Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient when frequency tends to zero. The results are
discussed in terms of the vibration wavefunction that combines features of
localized and extended modes.Comment: 8 pages, 9 figure
Spectrum and thermodynamic properties of two-dimensional N=(1,1) super Yang-Mills theory with fundamental matter and a Chern-Simons term
We consider N=(1,1) super Yang-Mills theory in 1+1 dimensions with
fundamentals at large-N_c. A Chern-Simons term is included to give mass to the
adjoint partons. Using the spectrum of the theory, we calculate thermodynamic
properties of the system as a function of the temperature and the Yang-Mills
coupling. In the large-N_c limit there are two non-communicating sectors, the
glueball sector, which we presented previously, and the meson-like sector that
we present here. We find that the meson-like sector dominates the
thermodynamics. Like the glueball sector, the meson sector has a Hagedorn
temperature T_H, and we show that the Hagedorn temperature grows with the
coupling. We calculate the temperature and coupling dependence of the free
energy for temperatures below T_H. As expected, the free energy for weak
coupling and low temperature grows quadratically with the temperature. Also the
ratio of the free energies at strong coupling compared to weak coupling,
r_{s-w}, for low temperatures grows quadratically with T. In addition, our data
suggest that r_{s-w} tends to zero in the continuum limit at low temperatures.Comment: 34 p
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