11,588 research outputs found
Ultracold collisions of metastable helium atoms
We report scattering lengths for the singlet Sigma g +, triplet Sigma u + and
quintet Sigma g + adiabatic molecular potentials relevant to collisions of two
metastable (n=2 triplet S) helium atoms as a function of the uncertainty in
these potentials. These scattering lengths are used to calculate experimentally
observable scattering lengths, elastic cross sections and inelastic rates for
any combination of states of the colliding atoms, at temperatures where the
Wigner threshold approximation is valid.Comment: 20 pages, 8 figures, RevTeX, epsf. Small additions of tex
Right eigenvalue equation in quaternionic quantum mechanics
We study the right eigenvalue equation for quaternionic and complex linear
matrix operators defined in n-dimensional quaternionic vector spaces. For
quaternionic linear operators the eigenvalue spectrum consists of n complex
values. For these operators we give a necessary and sufficient condition for
the diagonalization of their quaternionic matrix representations. Our
discussion is also extended to complex linear operators, whose spectrum is
characterized by 2n complex eigenvalues. We show that a consistent analysis of
the eigenvalue problem for complex linear operators requires the choice of a
complex geometry in defining inner products. Finally, we introduce some
examples of the left eigenvalue equations and highlight the main difficulties
in their solution.Comment: 24 pages, AMS-Te
Quaternionic Electroweak Theory
We explicitly develop a quaternionic version of the electroweak theory, based
on the local gauge group . The need of a complex
projection for our Lagrangian and the physical significance of the anomalous
scalar solutions are also discussed.Comment: 12 pages, Revtex, submitted to J. Phys.
Quaternionic Electroweak Theory and CKM Matrix
We find in our quaternionic version of the electroweak theory an apparently
hopeless problem: In going from complex to quaternions, the calculation of the
real-valued parameters of the CKM matrix drastically changes. We aim to explain
this quaternionic puzzle.Comment: 8, Revtex, Int. J. Theor. Phys. (to be published
Quaternionic potentials in non-relativistic quantum mechanics
We discuss the Schrodinger equation in presence of quaternionic potentials.
The study is performed analytically as long as it proves possible, when not, we
resort to numerical calculations. The results obtained could be useful to
investigate an underlying quaternionic quantum dynamics in particle physics.
Experimental tests and proposals to observe quaternionic quantum effects by
neutron interferometry are briefly reviewed.Comment: 21 pages, 16 figures (ps), AMS-Te
Transport through Zero-Dimensional States in a Quantum Dot
We have studied the electron transport through zero-dimensional (0D) states. 0D states are formed when one-dimensional edge channels are confined in a quantum dot. The quantum dot is defined in a two-dimensional electron gas with a split gate technique. To allow electronic transport, connection to the dot is arranged via two quantum point contacts, which have adjustable selective transmission properties for edge channels. The 0D states show up as pronounced oscillations in the conductance (up to 40% of e2/h), when the flux enclosed by the confined edge channel is varied, either by changing the magnetic field or the gate voltage. A prerequisite for the appearance of 0D states is that the transport through the entire device is adiabatic (i.e. with conservation of quantum numbers), which will be shown to occur at high magnetic field. The experimental results are in good agreement with theory and show that in the ballistic quantum Hall regime the current is carried entirely by edge channels.
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