3,619 research outputs found
Empiric Models of the Earth's Free Core Nutation
Free core nutation (FCN) is the main factor that limits the accuracy of the
modeling of the motion of Earth's rotational axis in the celestial coordinate
system. Several FCN models have been proposed. A comparative analysis is made
of the known models including the model proposed by the author. The use of the
FCN model is shown to substantially increase the accuracy of the modeling of
Earth's rotation. Furthermore, the FCN component extracted from the observed
motion of Earth's rotational axis is an important source for the study of the
shape and rotation of the Earth's core. A comparison of different FCN models
has shown that the proposed model is better than other models if used to
extract the geophysical signal (the amplitude and phase of FCN) from
observational data.Comment: 8 pages, 3 figures; minor update of the journal published versio
Wino Dark Matter in light of the AMS-02 2015 Data
The AMS-02 collaboration has recently reported the antiproton to proton ratio
with improved accuracy. In view of uncertainties of the production and the
propagation of the cosmic rays, the observed ratio is still consistent with the
secondary astrophysical antiproton to proton ratio. However, it is nonetheless
enticing to examine whether the observed spectrum can be explained by a
strongly motivated dark matter, the wino dark matter. As we will show, we find
that the antiproton flux from the wino annihilation can explain the observed
spectrum well for its mass range 2.5-3 TeV. The fit to data becomes
particularly well compared to the case without the annihilation for the thermal
wino dark matter case with a mass about 3 TeV. The ratio is predicted to be
quickly decreased at the energy several hundreds of GeV, if this possibility is
true, and it will be confirmed or ruled out in near future when the AMS-02
experiment accumulates enough data at this higher energy region.Comment: 6 pages, 2 figures, version accepted for publication in PRD (Rapid
Communication
Mass of Decaying Wino from AMS-02 2014
We revisit the decaying wino dark matter scenario in the light of the updated
positron fraction, electron and positron fluxes in cosmic ray recently reported
by the AMS-02 collaboration. We show the AMS-02 results favor the mass of the
wino dark matter at around a few TeV, which is consistent with the prediction
on the wino mass in the pure gravity mediation model.Comment: 10 pages, 1 figur
Photon and spin dependence of the resonance lines shape in the strong coupling regime
We study the quantum dynamics of a spin ensemble coupled to cavity photons.
Recently, related experimental results have been reported, showing the
existence of the strong coupling regime in such systems. We study the
eigenenergy distribution of the multi-spin system (following the Tavis-Cummings
model) which shows a peculiar structure as a function of the number of cavity
photons and of spins. We study how this structure causes changes in the
spectrum of the admittance in the linear response theory, and also the
frequency dependence of the excited quantities in the stationary state under a
probing field. In particular, we investigate how the structure of the higher
excited energy levels changes the spectrum from a double-peak structure (the
so-called vacuum field Rabi splitting) to a single peak structure. We also
point out that the spin dynamics in the region of the double-peak structure
corresponds to recent experiments using cavity ringing while in region of the
single peak structure, it corresponds to the coherent Rabi oscillation in a
driving electromagnetic filed. Using a standard Lindblad type mechanism, we
study the effect of dissipations on the line width and separation in the
computed spectra. In particular, we study the relaxation of the total spin in
the general case of a spin ensemble in which the total spin of the system is
not specified. The theoretical results are correlated with experimental
evidence of the strong coupling regime, achieved with a spin 1/2 ensemble
Image quality in double- and triple-intensity ghost imaging with classical partially polarized light
Classical ghost imaging is a correlation-imaging technique in which the image
of the object is found through intensity correlations of light. We analyze
three different quality parameters, namely the visibility, the signal-to-noise
ratio (SNR), and the contrast-to-noise ratio (CNR), to assess the performance
of double- and triple-intensity correlation-imaging setups. The source is a
random partially polarized beam of light obeying Gaussian statistics and the
image quality is evaluated as a function of the degree of polarization (DoP).
We show that the visibility improves when the DoP and the order of imaging
increase, while the SNR behaves oppositely. The CNR is for the most part
independent of DoP and the imaging order. The results are important for the
development of new imaging devices using partially polarized light.Comment: Added 2 references, corrected a few typos and revised text slightly.
Results unchange
Precise determination of two-carrier transport properties in the topological insulator TlBiSe
We report the electric transport study of the three-dimensional topological
insulator TlBiSe. We applied a newly developed analysis procedure and
precisely determined two-carrier transport properties. Magnetotransport
properties revealed a multicarrier conduction of high- and low-mobility
electrons in the bulk, which was in qualitative agreement with angle-resolved
photoemission results~[K. Kuroda , Phys. Rev. Lett. , 146801
(2010)]. The temperature dependence of the Hall mobility was explained well
with the conventional Bloch-Gr{\"u}neisen formula and yielded the Debye
temperature ~K. The results indicate that the
scattering of bulk electrons is dominated by acoustic phonons.Comment: 6 pages, 5 figures, to be published in Physical Review
Doping-induced quantum cross-over in ErTiSnO
We present the results of the investigation of magnetic properties of the
ErTiSnO series. For small doping values the ordering
temperature decreases linearly with while the moment configuration remains
the same as in the parent compound. Around doping level we
observe a change in the behavior, where the ordering temperature starts to
increase and new magnetic Bragg peaks appear. For the first time we present
evidence of a long-range order (LRO) in ErSnO () below
mK. It is revealed that the moment configuration corresponds to a
Palmer-Chalker type with a value of the magnetic moment significantly
renormalized compared to . We discuss our results in the framework of a
possible quantum phase transition occurring close to .Comment: accepted in PRB Rapi
- …