5,077 research outputs found
Effects of heavy Majorana neutrinos at lepton-proton colliders
We discuss the prospects of detecting the processes
and
() under the conditions of the present collider
HERA and of future colliders. These high-energy processes are assumed to be
mediated by the exchange of heavy Majorana neutrinos (HMN). We consider two
simple scenarios for the HMN mass spectrum: the effective singlet () and the effective doublet (). For the latter
case, the cross section includes information about CP-violating phases.Comment: 5pages, 2 figures; published in conference proceedings: Particle
Physics in Laboratory, Space and Universe, 11th. Lomonosov Conf. on
Elementary Particle Physics (Moscow, 21-27 August 2003) (Singapore, World
Scientific, 2005
Electron angular correlation in neutrinoless double beta decay and new physics
The angular correlation of the electrons in the neutrinoless double beta
decay () is calculated taking into account the nucleon recoil, the
and -waves for the electrons and the electron mass using a general
Lorentz invariant effective Lagrangian. We show that the angular coefficient is
essentially independent of the nuclear matrix element models. We work out the
angular coefficient in several scenarios for new physics, in particular, in the
left-right symmetric models.Comment: 5 pages, 1 figure; to appear in the Proceedings of the 13th Lomonosov
Conference on Elementary Particle Physics, 23 --29 August 2007, Moscow,
Russi
Propagation of axions in a strongly magnetized medium
The polarization operator of an axion in a degenerate gas of electrons
occupying the ground-state Landau level in a superstrong magnetic field G is investigated in a model with a
tree-level axion-electron coupling. It is shown that a dynamic axion mass,
which can fall within the allowed range of values , is generated under the conditions of strongly
magnetized neutron stars. As a result, the dispersion relation for axions is
appreciably different from that in a vacuum.Comment: RevTex, no figures, 13 pages, Revised version of the paper published
in J. Exp. Theor. Phys. {\bf 88}, 1 (1999
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
Homogenization of the planar waveguide with frequently alternating boundary conditions
We consider Laplacian in a planar strip with Dirichlet boundary condition on
the upper boundary and with frequent alternation boundary condition on the
lower boundary. The alternation is introduced by the periodic partition of the
boundary into small segments on which Dirichlet and Neumann conditions are
imposed in turns. We show that under the certain condition the homogenized
operator is the Dirichlet Laplacian and prove the uniform resolvent
convergence. The spectrum of the perturbed operator consists of its essential
part only and has a band structure. We construct the leading terms of the
asymptotic expansions for the first band functions. We also construct the
complete asymptotic expansion for the bottom of the spectrum
Spectral and localization properties of the Dirichlet wave guide with two concentric Neumann discs
Bound states of the Hamiltonian describing a quantum particle living on three
dimensional straight strip of width are investigated. We impose the Neumann
boundary condition on the two concentric windows of the radii and
located on the opposite walls and the Dirichlet boundary condition on the
remaining part of the boundary of the strip. We prove that such a system
exhibits discrete eigenvalues below the essential spectrum for any .
When and tend to the infinity, the asymptotic of the eigenvalue is
derived. A comparative analysis with the one-window case reveals that due to
the additional possibility of the regulating energy spectrum the anticrossing
structure builds up as a function of the inner radius with its sharpness
increasing for the larger outer radius. Mathematical and physical
interpretation of the obtained results is presented; namely, it is derived that
the anticrossings are accompanied by the drastic changes of the wave function
localization. Parallels are drawn to the other structures exhibiting similar
phenomena; in particular, it is proved that, contrary to the two-dimensional
geometry, at the critical Neumann radii true bound states exist.Comment: 25 pages, 7 figure
Distant perturbation asymptotics in window-coupled waveguides. I. The non-threshold case
We consider a pair of adjacent quantum waveguides, in general of different
widths, coupled laterally by a pair of windows in the common boundary, not
necessarily of the same length, at a fixed distance. The Hamiltonian is the
respective Dirichlet Laplacian. We analyze the asymptotic behavior of the
discrete spectrum as the window distance tends to infinity for the generic
case, i.e. for eigenvalues of the corresponding one-window problems separated
from the threshold
1RXS J180834.7+101041 is a new cataclysmic variable with non-uniform disc
Results of photometric and spectroscopic investigations of the recently
discovered disc cataclysmic variable star 1RXS J180834.7+101041 are presented.
Emission spectra of the system show broad double peaked hydrogen and helium
emission lines. Doppler maps for the hydrogen lines demonstrate strongly
non-uniform emissivity distribution in the disc, similar to that found in IP
Peg. It means that the system is a new cataclysmic variable with a spiral
density wave in the disc. Masses of the components (M_WD = 0.8 +/- 0.22 M_sun
and M_RD = 0.14 +/- 0.02 M_sun), and the orbit inclination (i = 78 +/- 1.5 deg)
were estimated using the various well-known relations for cataclysmic
variables.Comment: 4 pages, 3 figures, conference "European White Dwarf Workshop, 2010",
Tuebingen, German
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