106,909 research outputs found
Using MiniBooNE neutral current elastic cross section results to constrain 3+1 sterile neutrino models
The MiniBooNE Neutral Current Elastic (NCEL) cross section results are used
to extract limits in the plane for a
3+1 sterile neutrino model with a mass splitting eV. GENIE is used with a cross section model close to the one
employed by MiniBooNE to make event rate predictions using simulations on the
MiniBooNE target material CH. The axial mass is a free parameter in all
fits. Sterile modifications to the flux and changes to the cross section in the
simulation relate the two and allow limits to be set on sterile neutrino mixing
using cross section results. The large axial mass problem makes it necessary
for experiments to perform their own axial mass fits, but a prior fit to the
same dataset could mask a sterile oscillation signal if the sterile and cross
section model parameters are not independent. We find that for the NCEL dataset
there are significant correlations between the sterile and cross section model
parameters, making a fit to both models simultaneously necessary to get robust
results. Failure to do this results in stronger than warranted limits on the
sterile parameters. The general problems that the current uncertainty on
charged-current quasi-elastic (CCQE) and NCEL cross sections at MiniBooNE
energies pose for sterile neutrino measurements are discussed.Comment: Final version accepted for publication in JHE
Secrecy Wireless Information and Power Transfer in Fading Wiretap Channel
Simultaneous wireless information and power transfer (SWIPT) has recently
drawn significant interests for its dual use of radio signals to provide
wireless data and energy access at the same time. However, a challenging
secrecy communication issue arises as the messages sent to the information
receivers (IRs) may be eavesdropped by the energy receivers (ERs), which are
presumed to harvest energy only from the received signals. To tackle this
problem, we propose in this paper an artificial noise (AN) aided transmission
scheme to facilitate the secrecy information transmission to IRs and yet meet
the energy harvesting requirement for ERs, under the assumption that the AN can
be cancelled at IRs but not at ERs. Specifically, the proposed scheme splits
the transmit power into two parts, to send the confidential message to the IR
and an AN to interfere with the ER, respectively. Under a simplified three-node
wiretap channel setup, the transmit power allocations and power splitting
ratios over fading channels are jointly optimized to minimize the outage
probability for delay-limited secrecy information transmission, or to maximize
the average rate for no-delay-limited secrecy information transmission, subject
to a combination of average and peak power constraints at the transmitter as
well as an average energy harvesting constraint at the ER. Both the secrecy
outage probability minimization and average rate maximization problems are
shown to be non-convex, for each of which we propose the optimal solution based
on the dual decomposition as well as suboptimal solution based on the
alternating optimization. Furthermore, two benchmark schemes are introduced for
comparison. Finally, the performances of proposed schemes are evaluated by
simulations in terms of various trade-offs for wireless (secrecy) information
versus energy transmissions.Comment: to appear in IEEE Transactions on Vehicular Technolog
Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal
We report results of 75As nuclear magnetic resonance (NMR) experiments on a
self-flux grown single crystal of BaFe2As2. A first-order antiferromagnetic
(AF) transition near 135 K was detected by the splitting of NMR lines, which is
accompanied by simultaneous structural transition as evidenced by a sudden
large change of the electric field gradient tensor at the As site. The NMR
results lead almost uniquely to the stripe spin structure in the AF phase. The
data of spin-lattice relaxation rate indicate development of anisotropic spin
fluctuations of the stripe-type with decreasing temperature in the paramagnetic
phase.Comment: 7 pages, 7 figures, accepted for publication in J. Phys. Soc. Jp
Wireless information and power transfer: from scientific hypothesis to engineering practice
Recently, there has been substantial research interest in the subject of Simultaneous Wireless Information andPower Transfer (SWIPT) owing to its cross-disciplinary appeal and its wide-ranging application potential, whichmotivates this overview. More explicitly, we provide a brief survey of the state-of-the-art and introduce severalpractical transceiver architectures that may facilitate its implementation. Moreover, the most important link-levelas well as system-level design aspects are elaborated on, along with a variety of potential solutions and researchideas. We envision that the dual interpretation of Radio Frequency (RF) signals creates new opportunities as wellas challenges requiring substantial research, innovation and engineering efforts
Improved +He potentials by inversion, the tensor force and validity of the double folding model
Improved potential solutions are presented for the inverse scattering problem
for +He data. The input for the inversions includes both the data of
recent phase shift analyses and phase shifts from RGM coupled-channel
calculations based on the NN Minnesota force. The combined calculations provide
a more reliable estimate of the odd-even splitting of the potentials than
previously found, suggesting a rather moderate role for this splitting in
deuteron-nucleus scattering generally. The approximate parity-independence of
the deuteron optical potentials is shown to arise from the nontrivial
interference between antisymmetrization and channel coupling to the deuteron
breakup channels. A further comparison of the empirical potentials established
here and the double folding potential derived from the M3Y effective NN force
(with the appropriate normalisation factor) reveals strong similarities. This
result supports the application of the double folding model, combined with a
small Majorana component, to the description even of such a loosely bound
projectile as the deuteron. In turn, support is given for the application of
iterative-perturbative inversion in combination with the double folding model
to study fine details of the nucleus-nucleus potential. A -He tensor
potential is also derived to reproduce correctly the negative Li quadrupole
moment and the D-state asymptotic constant.Comment: 22 pages, 12 figures, in Revte
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