2,262 research outputs found
The Quest for the Heaviest Uranium Isotope
We study Uranium isotopes and surrounding elements at very large neutron
number excess. Relativistic mean field and Skyrme-type approaches with
different parametrizations are used in the study. Most models show clear
indications for isotopes that are stable with respect to neutron emission far
beyond N=184 up to the range of around N=258.Comment: 4 pages, 5. figure
Transport Equations from Liouville Equations for Fractional Systems
We consider dynamical systems that are described by fractional power of
coordinates and momenta. The fractional powers can be considered as a
convenient way to describe systems in the fractional dimension space. For the
usual space the fractional systems are non-Hamiltonian. Generalized transport
equation is derived from Liouville and Bogoliubov equations for fractional
systems. Fractional generalization of average values and reduced distribution
functions are defined. Hydrodynamic equations for fractional systems are
derived from the generalized transport equation.Comment: 11 pages, LaTe
Path Integral for Quantum Operations
In this paper we consider a phase space path integral for general
time-dependent quantum operations, not necessarily unitary. We obtain the path
integral for a completely positive quantum operation satisfied Lindblad
equation (quantum Markovian master equation). We consider the path integral for
quantum operation with a simple infinitesimal generator.Comment: 24 pages, LaTe
Analytical on-shell QED results: 3-loop vacuum polarization, 4-loop beta-function and the muon anomaly
We present the results of analytical calculations of the 3-loop contributions
to the asymptotic photon vacuum polarization function, in the on shell scheme,
and of the 4-loop contributions to the on shell QED beta-function. These are
used to evaluate various 4-loop and 5-loop contributions to the muon anomaly.
Our analytical contributions to (g-2)_\mu differ significantly from previous
numerical results. A very recent numerical re-evaluation of 4-loop muon-anomaly
contributions has yielded results much closer to ours.Comment: LaTex, 11 pages, figures available from O.V.T. CERN--TH. 6602/92,
OUT--4102--39, BI--TP--92/3
Propagation of wave packets in randomly stratified media
The propagation of a narrow-band signal radiated by a point source in a
randomly layered absorbing medium is studied asymptotically in the
weak-scattering limit. It is shown that in a disordered stratified medium that
is homogeneous on average a pulse is channelled along the layers in a narrow
strip in the vicinity of the source. The space-time distribution of the pulse
energy is calculated. Far from the source, the shape of wave packets is
universal and independent of the frequency spectrum of the radiated signal.
Strong localization effects manifest themselves also as a low-decaying tail of
the pulse and a strong time delay in the direction of stratification. The
frequency-momentum correlation function in a one-dimensional random medium is
calculated.Comment: 11 pages, 3 figures, Revtex-4. Submitted to Phys. Rev.
Fractional Variations for Dynamical Systems: Hamilton and Lagrange Approaches
Fractional generalization of an exterior derivative for calculus of
variations is defined. The Hamilton and Lagrange approaches are considered.
Fractional Hamilton and Euler-Lagrange equations are derived. Fractional
equations of motion are obtained by fractional variation of Lagrangian and
Hamiltonian that have only integer derivatives.Comment: 21 pages, LaTe
Phase-Space Metric for Non-Hamiltonian Systems
We consider an invariant skew-symmetric phase-space metric for
non-Hamiltonian systems. We say that the metric is an invariant if the metric
tensor field is an integral of motion. We derive the time-dependent
skew-symmetric phase-space metric that satisfies the Jacobi identity. The
example of non-Hamiltonian systems with linear friction term is considered.Comment: 12 page
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