3,396 research outputs found
Lepton pair production by high-energy neutrino in an external electromagnetic field
The process of the lepton pair production by a neutrino propagating in an
external electromagnetic field is investigated in the framework of the Standard
Model. Relatively simple exact expression for the probability as the single
integral is obtained, which is suitable for a quantitative analysis.Comment: 9 pages, LATEX, 2 PS figures, submitted to Modern Physics Letters
Exchange-assisted tunneling in the classical limit
The exchange interaction and correlations may produce a power-law decay
instead of the usual exponential decrease of the wave function under potential
barrier. The exchange-assisted tunneling vanishes in the classical limit,
however, the dependence on the Planck constant h is different from that for a
conventional single-particle tunneling
Chaplygin ball over a fixed sphere: explicit integration
We consider a nonholonomic system describing a rolling of a dynamically
non-symmetric sphere over a fixed sphere without slipping. The system
generalizes the classical nonholonomic Chaplygin sphere problem and it is shown
to be integrable for one special ratio of radii of the spheres. After a time
reparameterization the system becomes a Hamiltonian one and admits a separation
of variables and reduction to Abel--Jacobi quadratures. The separating
variables that we found appear to be a non-trivial generalization of
ellipsoidal (spheroconical) coordinates on the Poisson sphere, which can be
useful in other integrable problems.
Using the quadratures we also perform an explicit integration of the problem
in theta-functions of the new time.Comment: This is an extended version of the paper to be published in Regular
and Chaotic Dynamics, Vol. 13 (2008), No. 6. Contains 20 pages and 2 figure
The distribution of stresses and strains in the mating elements disk tools working bodies of roadheaders
Presents the results of modeling the stress-strain state in the mating structural elements of the attachment disk tools various design on triangular and tetrahedral prisms working bodies of roadheaders selective action in the destruction of coalface of heterogeneous structure
Influence of the Rigid Connection Between Discs in the Tetrahedral Prisms on Equivalent Stresses When Cutting Work Faces
This paper presents the results of modeling of the stressed state of structural elements of the paired fastening points of the two disc tools to the tetrahedral prisms of the working bodies of the roadheaders of selective action when cutting work faces of heterogeneous structure. The advantages of cooperative mode rotation to separate two disc tools on each of the tetrahedral prisms placed between the axial cutting crowns
Investigation of the microstructure, mechanical properties and thermal stability of nanocomposite coatings based on amorphous carbon
The Ti-C-Ni-Cr and Ti-C-Ni-Cr-Al-Si nanocomposite coatings based on amorphous carbon and the nanosized particles were synthesized by magnetron method. The results of the microstructure features and mechanical properties investigations of these coatings are presented. The thermal stability of microstructure and properties of these coatings at tempering up to 900°C were investigated. These coatings have a high (11–18 GPa) hardness, low (μ < 0.2) the coefficient of friction and high thermal stability of the microstructure and properties up to 700°C. The features of elastically stressed state of nanosized particles in these coatings were founded. A high local internal stresses in the TiC nanoscale particles do not observed
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