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