7,982 research outputs found
Quantization of Point-Like Particles and Consistent Relativistic Quantum Mechanics
We revise the problem of the quantization of relativistic particle models
(spinless and spinning), presenting a modified consistent canonical scheme. One
of the main point of the modification is related to a principally new
realization of the Hilbert space. It allows one not only to include arbitrary
backgrounds in the consideration but to get in course of the quantization a
consistent relativistic quantum mechanics, which reproduces literally the
behavior of the one-particle sector of the corresponding quantum field. In
particular, in a physical sector of the Hilbert space a complete positive
spectrum of energies of relativistic particles and antiparticles is reproduced,
and all state vectors have only positive norms.Comment: 57 pages, LaTex fil
The MRO-accompanied modes of Re-implantation into SiO2-host matrix: XPS and DFT based scenarios
The following scenarios of Re-embedding into SiO2-host by pulsed
Re-implantation were derived and discussed after XPS-and-DFT electronic
structure qualification: (i) low Re-impurity concentration mode -> the
formation of combined substitutional and interstitial impurities with
Re2O7-like atomic and electronic structures in the vicinity of oxygen
vacancies; (ii) high Re-impurity concentration mode -> the fabrication of
interstitial Re-metal clusters with the accompanied formation of ReO2-like
atomic structures and (iii) an intermediate transient mode with Re-impurity
concentration increase, when the precursors of interstitial defect clusters are
appeared and growing in the host-matrix structure occur. An amplification
regime of Re-metal contribution majority to the final Valence Band structure
was found as one of the sequences of intermediate transient mode. It was shown
that most of the qualified and discussed modes were accompanied by the MRO
(middle range ordering) distortions in the initial oxygen subnetwork of the
a-SiO2 host-matrix because of the appeared mixed defect configurations.Comment: 19 pages, 7 figures, accepted to J. Alloys and Compound
Electronic band gap reduction and intense luminescence in Co and Mn ion-implanted SiO
Cobalt and manganese ions are implanted into SiO over a wide range of
concentrations. For low concentrations, the Co atoms occupy interstitial
locations, coordinated with oxygen, while metallic Co clusters form at higher
implantation concentrations. For all concentrations studied here, Mn ions
remain in interstitial locations and do not cluster. Using resonant x-ray
emission spectroscopy and Anderson impurity model calculations, we determine
the strength of the covalent interaction between the interstitial ions and the
SiO valence band, finding it comparable to Mn and Co monoxides. Further, we
find an increasing reduction in the SiO electronic band gap for increasing
implantation concentration, due primarily to the introduction of Mn- and
Co-derived conduction band states. We also observe a strong increase in a band
of x-ray stimulated luminescence at 2.75 eV after implantation, attributed to
oxygen deficient centers formed during implantation.Comment: 8 pages, 6 figure
Quantization of (2+1)-spinning particles and bifermionic constraint problem
This work is a natural continuation of our recent study in quantizing
relativistic particles. There it was demonstrated that, by applying a
consistent quantization scheme to a classical model of a spinless relativistic
particle as well as to the Berezin-Marinov model of 3+1 Dirac particle, it is
possible to obtain a consistent relativistic quantum mechanics of such
particles. In the present article we apply a similar approach to the problem of
quantizing the massive 2+1 Dirac particle. However, we stress that such a
problem differs in a nontrivial way from the one in 3+1 dimensions. The point
is that in 2+1 dimensions each spin polarization describes different fermion
species. Technically this fact manifests itself through the presence of a
bifermionic constant and of a bifermionic first-class constraint. In
particular, this constraint does not admit a conjugate gauge condition at the
classical level. The quantization problem in 2+1 dimensions is also interesting
from the physical viewpoint (e.g. anyons). In order to quantize the model, we
first derive a classical formulation in an effective phase space, restricted by
constraints and gauges. Then the condition of preservation of the classical
symmetries allows us to realize the operator algebra in an unambiguous way and
construct an appropriate Hilbert space. The physical sector of the constructed
quantum mechanics contains spin-1/2 particles and antiparticles without an
infinite number of negative-energy levels, and exactly reproduces the
one-particle sector of the 2+1 quantum theory of a spinor field.Comment: LaTex, 24 pages, no figure
Quantization of the Relativistic Particle
We revise the problem of the quantization of relativistic particle,
presenting a modified consistent canonical scheme, which allows one not only to
include arbitrary backgrounds in the consideration but to get in course of the
quantization a consistent relativistic quantum mechanics, which reproduces
literally the behavior of the one-particle sector of the corresponding quantum
field. At the same time this construction presents a possible solution of the
well-known old problem how to construct a consistent quantum mechanics on the
base of a relativistic wave equation.Comment: 10 page
Identification of earthquake precursors in the hydrogeochemical and geoacoustic data for the Kamchatka peninsula by flicker-noise spectroscopy
A phenomenological systems approach for identifying potential precursors in
multiple signals of different types for the same local seismically active
region is proposed based on the assumption that a large earthquake may be
preceded by a system reconfiguration (preparation) at different time and space
scales. A nonstationarity factor introduced within the framework of
flicker-noise spectroscopy, a statistical physics approach to the analysis of
time series, is used as the dimensionless criterion for detecting qualitative
(precursory) changes within relatively short time intervals in arbitrary
signals. Nonstationarity factors for chlorine-ion concentration variations in
the underground water of two boreholes on the Kamchatka peninsula and
geacoustic emissions in a deep borehole within the same seismic zone are
studied together in the time frame around a large earthquake on October 8,
2001. It is shown that nonstationarity factor spikes (potential precursors)
take place in the interval from 70 to 50 days before the earthquake for the
hydrogeochemical data and at 29 and 6 days in advance for the geoacoustic data.Comment: 8 pages, 4 figures; to be published in Nat. Hazards Earth Syst. Sc
The quasi-bi-Hamiltonian formulation of the Lagrange top
Starting from the tri-Hamiltonian formulation of the Lagrange top in a
six-dimensional phase space, we discuss the possible reductions of the Poisson
tensors, the vector field and its Hamiltonian functions on a four-dimensional
space. We show that the vector field of the Lagrange top possesses, on the
reduced phase space, a quasi-bi-Hamiltonian formulation, which provides a set
of separation variables for the corresponding Hamilton-Jacobi equation.Comment: 12 pages, no figures, LaTeX, to appear in J. Phys. A: Math. Gen.
(March 2002
Quantum Phase Transition in Pr2CuO4 to Collinear Spin State in Inclined Magnetic Field: A Neutron Diffraction Observation
In the external field slightly inclined to the - or y-axis of the
frustrated tetragonal atiferromagnet Pr2CuO4, a transition is discovered from
the phase with orthogonal antiferromagnetic spin subsystems along [1,0,0] and
[0,1,0] to the phase with the collinear spins. This phase is shown to be due to
the pseudodipolar interaction, and transforms into the spin-flop phase S perp H
asymptotically at very high field. The discovered phase transition holds at T=0
and is a quantum one, with the transition field being the critical point and
the angle between two subsystems being the order parameter
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