39,476 research outputs found
Precise calculation of parity nonconservation in cesium and test of the standard model
We have calculated the 6s-7s parity nonconserving (PNC) E1 transition
amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in
the calculation of the correlations and have included all significant
contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times
10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations
used for the interpretation of Cs PNC experiments. The resulting nuclear weak
charge Q_{W} for Cs deviates by about 2 standard deviations from the value
predicted by the standard model.Comment: 24 pages, 8 figure
Constellation Mapping for Physical-Layer Network Coding with M-QAM Modulation
The denoise-and-forward (DNF) method of physical-layer network coding (PNC)
is a promising approach for wireless relaying networks. In this paper, we
consider DNF-based PNC with M-ary quadrature amplitude modulation (M-QAM) and
propose a mapping scheme that maps the superposed M-QAM signal to coded
symbols. The mapping scheme supports both square and non-square M-QAM
modulations, with various original constellation mappings (e.g. binary-coded or
Gray-coded). Subsequently, we evaluate the symbol error rate and bit error rate
(BER) of M-QAM modulated PNC that uses the proposed mapping scheme. Afterwards,
as an application, a rate adaptation scheme for the DNF method of PNC is
proposed. Simulation results show that the rate-adaptive PNC is advantageous in
various scenarios.Comment: Final version at IEEE GLOBECOM 201
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