Strong vortex-antivortex fluctuations in the type II superconducting film

The small size vortex-antivortex pairs proliferation in type II superconducting film is considered for the wide interval of temperatures below Tc. The corresponding contribution to free energy is calculated. It is shown that these fluctuations give the main contribution to the heat capacity of the film both at low temperatures and in the vicinity of transition

Quasitriangularity and enveloping algebras for inhomogeneous quantum groups

Coquasitriangular universal ${\cal R}$ matrices on quantum Lorentz and quantum Poincar\'e groups are classified. The results extend (under certain assumptions) to inhomogeneous quantum groups of [10]. Enveloping algebras on those objects are described.Comment: 18 pages, LaTeX file, minor change

The Dirac operator and gamma matrices for quantum Minkowski spaces

Gamma matrices for quantum Minkowski spaces are found. The invariance of the corresponding Dirac operator is proven. We introduce momenta for spin 1/2 particles and get (in certain cases) formal solutions of the Dirac equation.Comment: 25 pages, LaTeX fil

A new approach to calculate the transport matrix in RF cavities

A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm will be implemented into the MARS15 code.Comment: 4 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1 Apr 2011. New York, US

Charge-exchange resonances and restoration of the Wigner SU(4)-symmetry in heavy and superheavy nuclei

Energies of the giant Gamow-Teller and analog resonances - $E_{\rm G}$ and $E_{\rm A}$, are presented, calculated using the microscopic theory of finite Fermi system. The calculated differences $\Delta E_{\rm G-A}=E_{\rm G}-E_{\rm A}$ go to zero in heavier nuclei indicating the restoration of Wigner SU(4)-symmetry. The calculated $\Delta E_{\rm G-A}$ values are in good agreement with the experimental data. The average deviation is 0.30 MeV for the 33 considered nuclei for which experimental data is available. The $\Delta E_{\rm G-A}$ values were calculated for heavy and superheavy nuclei up to the mass number $A$= 290. Using the experimental data for the analog resonances energies, the isotopic dependence of the difference of the Coulomb energies of neighboring nuclei isobars analyzed within the SU(4)-approach for more than 400 nuclei in the mass number range of $A$ = 3 - 244. The Wigner SU(4)-symmetry restoration for heavy and superheavy nuclei is confirmed. It is shown that the restoration of SU(4)-symmetry does not contradict the possibility of the existence of the "island of stability" in the region of superheavy nuclei.Comment: 5 pages, 2 figure

High-frequency oscillations in low-dimensional conductors and semiconductor superlattices induced by current in stack direction

A narrow energy band of the electronic spectrum in some direction in low-dimensional crystals may lead to a negative differential conductance and N-shaped I-V curve that results in an instability of the uniform stationary state. A well-known stable solution for such a system is a state with electric field domain. We have found a uniform stable solution in the region of negative differential conductance. This solution describes uniform high-frequency voltage oscillations. Frequency of the oscillation is determined by antenna properties of the system. The results are applicable also to semiconductor superlattices.Comment: 8 pages, 3 figure