30,073 research outputs found
On gauge-invariant Green function in 2+1 dimensional QED
Both the gauge-invariant fermion Green function and gauge-dependent
conventional Green function in dimensional QED are studied in the large
limit. In temporal gauge, the infra-red divergence of gauge-dependent
Green function is found to be regulariable, the anomalous dimension is found to
be . This anomalous dimension was argued to be
the same as that of gauge-invariant Green function. However, in Coulomb gauge,
the infra-red divergence of the gauge-dependent Green function is found to be
un-regulariable, anomalous dimension is even not defined, but the infra-red
divergence is shown to be cancelled in any gauge-invariant physical quantities.
The gauge-invariant Green function is also studied directly in Lorentz
covariant gauge and the anomalous dimension is found to be the same as that
calculated in temporal gauge.Comment: 8 pages, 6 figures, to appear in Phys. Rev.
Gauge-invariant Green function in 3+1 dimensional QED (QCD) and 2+1 dimensional Abelian (Non-Abelian) Chern-Simon theory
By applying the simple and effective method developed to study the the
gauge-invariant fermion Green function in dimensional non-compact QED,
we study the gauge-invariant Green function in dimensional QED and dimensional non-compact Chern-Simon theory. We also extend our results to
the corresponding non-Abelian gauge theories. Implications for
Fractional Quantum Hall effect are briefly discussed.Comment: 8 pages, 4 figures, published versio
Comparative study of microwave radiation-induced magnetoresistive oscillations induced by circularly- and linearly- polarized photo-excitation
A comparative study of the radiation-induced magnetoresistance oscillations
in the high mobility GaAs/AlGaAs heterostructure two dimensional electron
system (2DES) under linearly- and circularlypolarized microwave excitation
indicates a profound difference in the response observed upon rotating the
microwave launcher for the two cases, although circularly polarized microwave
radiation induced magnetoresistance oscillations observed at low magnetic
fields are similar to the oscillations observed with linearly polarized
radiation. For the linearly polarized radiation, the magnetoresistive response
is a strong sinusoidal function of the launcher rotation (or linear
polarization) angle, {\theta}. For circularly polarized radiation, the
oscillatory magnetoresistive response is hardly sensitive to {\theta}
A Universal Phase Diagram for PMN-xPT and PZN-xPT
The phase diagram of the Pb(Mg1/3Nb2/3)O3 and PbTiO3 solid solution (PMN-xPT)
indicates a rhombohedral ground state for x < 0.32. X-ray powder measurements
by Dkhil et al. show a rhombohedrally split (222) Bragg peak for PMN-10%PT at
80 K. Remarkably, neutron data taken on a single crystal of the same compound
with comparable q-resolution reveal a single resolution-limited (111) peak down
to 50 K, and thus no rhombohedral distortion. Our results suggest that the
structure of the outer layer of these relaxors differs from that of the bulk,
which is nearly cubic, as observed in PZN by Xu et al.Comment: Replaced Fig. 3 with better versio
The Relation of Thermal Fluctuation and Information-Entropy for One-Dimensional Rindler Oscillator
Within the framework of thermo-field-dynamics (TFD), the
information-entropies associated with the measurements of position and momentum
for one-dimensional Rindler oscillator are derived, and the connection between
its information-entropy and thermal fluctuation is obtained. A conclusion is
drawn that the thermal fluctuation leads to the loss of information.Comment: 14 pages, 1 figur
Analysis of Power-aware Buffering Schemes in Wireless Sensor Networks
We study the power-aware buffering problem in battery-powered sensor
networks, focusing on the fixed-size and fixed-interval buffering schemes. The
main motivation is to address the yet poorly understood size variation-induced
effect on power-aware buffering schemes. Our theoretical analysis elucidates
the fundamental differences between the fixed-size and fixed-interval buffering
schemes in the presence of data size variation. It shows that data size
variation has detrimental effects on the power expenditure of the fixed-size
buffering in general, and reveals that the size variation induced effects can
be either mitigated by a positive skewness or promoted by a negative skewness
in size distribution. By contrast, the fixed-interval buffering scheme has an
obvious advantage of being eminently immune to the data-size variation. Hence
the fixed-interval buffering scheme is a risk-averse strategy for its
robustness in a variety of operational environments. In addition, based on the
fixed-interval buffering scheme, we establish the power consumption
relationship between child nodes and parent node in a static data collection
tree, and give an in-depth analysis of the impact of child bandwidth
distribution on parent's power consumption.
This study is of practical significance: it sheds new light on the
relationship among power consumption of buffering schemes, power parameters of
radio module and memory bank, data arrival rate and data size variation,
thereby providing well-informed guidance in determining an optimal buffer size
(interval) to maximize the operational lifespan of sensor networks
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