1,310 research outputs found
Neutrino propagation in media and axis of complete polarization
We construct a spectral representation of neutrino propagator in moving
matter or in external magnetic field. In both cases there exists fixed
four-dimensional axis of polarization, such that the corresponding spin
projectors commute with propagator. As a result, all eigenvalues of propagator
and, consequently, dispersion laws for neutrino in media are classified
according to spin projection onto this axis. Use of the found spin projectors
simplifies essentially the eigenvalue problem and allows to build spectral
representation of propagator in moving matter or external magnetic field in
analogy with the vacuum propagator.Comment: 16 pages, journal versio
On Karatsuba's Problem Concerning the Divisor Function
We study an asymptotic behavior of the sum \sum\limits_{n\le x}\frac{\D
\tau(n)}{\D \tau(n+a)}. Here denotes the number of divisors of
and is a fixed integer.Comment: 32 page
Measurement of the neutron electric dipole moment by crystal diffraction
An experiment using a prototype setup to search for the neutron electric
dipole moment by measuring spin-rotation in a non-centrosymmetric crystal
(quartz) was carried out to investigate statistical sensitivity and systematic
effects of the method. It has been demonstrated that the concept of the method
works. The preliminary result of the experiment is ecm. The experiment showed that an accuracy of ecm can be obtained in 100 days data taking, using available
quartz crystals and neutron beams.Comment: 13 pages, 4 figure
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Testing the Annular Mode Autocorrelation Time Scale in Simple Atmospheric General Circulation Models
A new diagnostic for measuring the ability of atmospheric models to reproduce realistic low-frequency variability is introduced in the context of Held and Suarez’s 1994 proposal for comparing the dynamics of different general circulation models. A simple procedure to compute τ, the e-folding time scale of the annular mode autocorrelation function, is presented. This quantity concisely quantifies the strength of low-frequency variability in a model and is easy to compute in practice. The sensitivity of τ to model numerics is then studied for two dry primitive equation models driven with the Held–Suarez forcings: one pseudospectral and the other finite volume. For both models, τ is found to be unrealistically large when the horizontal resolutions are low, such as those that are often used in studies in which long integrations are needed to analyze model variability on low frequencies. More surprising is that it is found that, for the pseudospectral model, τ is particularly sensitive to vertical resolution, especially with a triangular truncation at wavenumber 42 (a very common resolution choice). At sufficiently high resolution, the annular mode autocorrelation time scale τ in both models appears to converge around values of 20–25 days, suggesting the existence of an intrinsic time scale at which the extratropical jet vacillates in the Held and Suarez system. The importance of τ for computing the correct response of a model to climate change is explicitly demonstrated by perturbing the pseudospectral model with simple torques. The amplitude of the model’s response to external forcing increases as τ increases, as suggested by the fluctuation–dissipation theorem
On gravity as an entropic force
We consider E. Verlinde's proposal that gravity is an entropic force -- we
shall call this theory entropic gravity (EG) -- and reanalyze a recent claim
that this theory is in contradiction with the observation of the
gravitationally-bound ground state of neutrons in the GRANIT experiment. We
find that EG does not necessarily contradict the existence of
gravitationally-bound quantum states of neutrons in the Earth's gravitational
field, since EG is equivalent to Newtonian gravity in this case. However,
certain transitions between the gravitationally-bound quantum states of
neutrons, in particular spontaneous decays of excited states, which can
hopefully be observed in future experiments, cannot be explained in the
framework of EG, unless essential ingredients are introduced into it.
Otherwise, a quantized description of gravity will be required.Comment: 6 pages, v2: the possibility that graviton may appear as an emergent
concept in EG is noted, few improvements in arguments and presentation, some
typos and grammar corrected. To appear in Phys. Lett.
Antiproton-Hydrogen annihilation at sub-kelvin temperatures
The main properties of the interaction of ultra low-energy antiprotons ( a.u.) with atomic hydrogen are established. They include the
elastic and inelastic cross sections and Protonium (Pn) formation spectrum. The
inverse Auger process () is taken into account in the
framework of an unitary coupled-channels model. The annihilation cross-section
is found to be several times smaller than the predictions made by the black
sphere absorption models. A family of nearthreshold metastable
states is predicited. The dependence of Protonium formation probability on the
position of such nearthreshold S-matrix singularities is analysed. An
estimation for the annihilation cross section is obtained.Comment: latex.tar.gz file, 22 pages, 9 figure
Trajectory Surface Hopping Study of the Li + Li2(X1Σg+) Dissociation Reaction
Trajectory surface hopping calculations are reported for the Li + Li2(X1Σg+) dissociation reaction over the range of translational energies 13 ≤ Etr/kcal mol-1 ≤ 80. Both potential energy surfaces for ground doublet Li3, which have been modeled from the double many-body expansion method (DMBE III), have been employed in the dynamics calculations. For the initial internal state (v = 0, j = 10), the behavior of the dissociative cross sections as a function of translational energy shows that nonadiabatic effects are important over the whole range of energies studied. Concerning the role of initial vibration, it has been found that, for Etr = 25 kcal mol-1 and j = 10, the adiabatic dissociative cross sections are enhanced as v increases from 0 to 20, while the nonadiabatic ones just slightly increase with the vibrational quantum number
SOCIAL NETWORKS AS A TOOL FOR IMPLEMENTATION OF SOCIAL-PSYCHOLOGICAL MECHANISMS OF ORGANIZATIONAL CULTURE
The article examines the possibilities of using virtual social networks for the implementation of socio-psychological mechanisms for the construction and development of organizational culture. The authors describe social networks as a special virtualized social environment, characterize and describe the features of interaction within it. In the work, much attention is paid to socio-psychological mechanisms - scoring, patricipation, the technology of the expanding core and cascade technology, as well as the organizational conditions for employee motivation
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