12,083 research outputs found
Adiabaticity and spectral splits in collective neutrino transformations
Neutrinos streaming off a supernova core transform collectively by
neutrino-neutrino interactions, leading to "spectral splits" where an energy
E_split divides the transformed spectrum sharply into parts of almost pure but
different flavors. We present a detailed description of the spectral split
phenomenon which is conceptually and quantitatively understood in an adiabatic
treatment of neutrino-neutrino effects. Central to this theory is a
self-consistency condition in the form of two sum rules (integrals over the
neutrino spectra that must equal certain conserved quantities). We provide
explicit analytic and numerical solutions for various neutrino spectra. We
introduce the concept of the adiabatic reference frame and elaborate on the
relative adiabatic evolution. Violating adiabaticity leads to the spectral
split being "washed out". The sharpness of the split appears to be represented
by a surprisingly universal function.Comment: 20 pages, revtex, 13 figure
Optically induced spin polarization of an electric current through a quantum dot
We examine electron transport through semiconductor quantum dot subject to a
continuous circularly polarized optical irradiation resonant to the electron -
heavy hole transition. Electrons having certain spin polarization experience
Rabi oscillation and their energy levels are shifted by the Rabi frequency.
Correspondingly, the equilibrium chemical potential of the leads and the
lead-to-lead bias voltage can be adjusted so only electrons with spin-up
polarization or only electrons with spin-down polarization contribute to the
current. The temperature dependence of the spin polarization of the current is
also discussed.Comment: Several misprints are correcte
Atmospheric neutrinos: LMA oscillations, Ue3 induced interference and CP-violation
We consider oscillations of the low energy (sub-GeV sample) atmospheric
neutrinos in the three neutrino context. We present the semi-analytic study of
the neutrino evolution and calculate characteristics of the e-like events
(total number, energy spectra and zenith angle distributions) in the presence
of oscillations. At low energies there are three different contributions to the
number of events: the LMA contribution (from electron-neutrino oscillations
driven by the solar oscillation parameters), the Ue3-contribution proportional
to s13**2, and the Ue3 - induced interference of the two amplitudes driven by
the solar oscillation parameters. The interference term is sensitive to the
CP-violation phase. We describe in details properties of these contributions.
We find that the LMA, the interference and Ue3 contributions can reach 5 - 6%,
2 - 3% and 1 - 2 % correspondingly. An existence of the significant (> 3 - 5 %)
excess of the e-like events in the sub-GeV sample and the absence of the excess
in the multi-GeV range testifies for deviation of the 2-3 mixing from maximum.
We consider a possibility to measure the deviation as well as the CP- violation
phase in future atmospheric neutrino studies.Comment: 30 pages, RevTeX4.0, 11 figures; improved figure
On the Clebsch-Gordan coefficients for the two-parameter quantum algebra
We show that the Clebsch - Gordan coefficients for the -
algebra depend on a single parameter Q = ,contrary to the explicit
calculation of Smirnov and Wehrhahn [J.Phys.A 25 (1992),5563].Comment: 5 page
Modelling chemical reactions using semiconductor quantum dots
We propose using semiconductor quantum dots for a simulation of chemical
reactions as electrons are redistributed among such artificial atoms. We show
that it is possible to achieve various reaction regimes and obtain different
reaction products by varying the speed of voltage changes applied to the gates
forming quantum dots. Considering the simplest possible reaction, , we show how the necessary initial state can be obtained and what
voltage pulses should be applied to achieve a desirable final product. Our
calculations have been performed using the Pechukas gas approach, which can be
extended for more complicated reactions
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