499 research outputs found
More on scattering of Chern-Simons vortices
I derive a general formalism for finding kinetic terms of the effective
Lagrangian for slowly moving Chern-Simons vortices. Deformations of fields
linear in velocities are taken into account. From the equations they must
satisfy I extract the kinetic term in the limit of coincident vortices. For
vortices passing one over the other there is locally the right-angle
scattering. The method is based on analysis of field equations instead of
action functional so it may be useful also for nonvariational equations in
nonrelativistic models of Condensed Matter Physics.Comment: discussion around Eq.(45) is generalised, one more condition for the
local right-angle scattering is adde
Tunnel splitting and quantum phase interference in biaxial ferrimagnetic particles at excited states
The tunneling splitting in biaxial ferrimagnetic particles at excited states
with an explicit calculation of the prefactor of exponent is obtained in terms
of periodic instantons which are responsible for tunneling at excited states
and is shown as a function of magnetic field applied along an arbitrary
direction in the plane of hard and medium axes. Using complex time
path-integral we demonstrate the oscillation of tunnel splitting with respect
to the magnitude and the direction of the magnetic field due to the quantum
phase interference of two tunneling paths of opposite windings . The
oscillation is gradually smeared and in the end the tunnel splitting
monotonously increases with the magnitude of the magnetic field when the
direction of the magnetic field tends to the medium axis. The oscillation
behavior is similar to the recent experimental observation with Fe
molecular clusters. A candidate of possible experiments to observe the effect
of quantum phase interference in the ferrimagnetic particles is proposed.Comment: 15 pages, 5 figures, acceptted to be pubblished in Physical Review
First and Second Order Vortex Dynamics
The low energy dynamics of vortices in selfdual Abelian Higgs theory is of
second order in vortex velocity and characterized by the moduli space metric.
When Chern-Simons term with small coefficient is added to the theory, we show
that a term linear in vortex velocity appears and can be consistently added to
the second order expression. We provides an additional check of the first and
second order terms by studying the angular momentum in the field theory. We
briefly explore other first order term due to small background electric charge
density and also the harmonic potential well for vortices given by the moment
of inertia.Comment: a rev tex file, 22 pages, no figur
Instantons and Yang-Mills Flows on Coset Spaces
We consider the Yang-Mills flow equations on a reductive coset space G/H and
the Yang-Mills equations on the manifold R x G/H. On nonsymmetric coset spaces
G/H one can introduce geometric fluxes identified with the torsion of the spin
connection. The condition of G-equivariance imposed on the gauge fields reduces
the Yang-Mills equations to phi^4-kink equations on R. Depending on the
boundary conditions and torsion, we obtain solutions to the Yang-Mills
equations describing instantons, chains of instanton-anti-instanton pairs or
modifications of gauge bundles. For Lorentzian signature on R x G/H, dyon-type
configurations are constructed as well. We also present explicit solutions to
the Yang-Mills flow equations and compare them with the Yang-Mills solutions on
R x G/H.Comment: 1+12 page
Gravitational Leptogenesis and Neutrino Mass Limit
Recently Davoudiasl {\it et al} \cite{steinhardt} have introduced a new type
of interaction between the Ricci scalar and the baryon current ,
and proposed a mechanism for baryogenesis, the
gravitational baryogenesis. Generally, however, vanishes in
the radiation dominated era. In this paper we consider a generalized form of
their interaction, and study again the possibility
of gravitational baryo(lepto)genesis. Taking , we will show
that does not vanish and the
required baryon number asymmetry can be {\it naturally} generated in the early
universe.Comment: 4 page
Chern-Simons Vortices in Supergravity
We study supersymmetric vortex solutions in three-dimensional abelian gauged
supergravity. First, we construct the general U(1)-gauged D=3, N=2 supergravity
whose scalar sector is an arbitrary Kahler manifold with U(1) isometry. This
construction clarifies the connection between local supersymmetry and the
specific forms of some scalar potentials previously found in the literature --
in particular, it provides the locally supersymmetric embedding of the abelian
Chern-Simons Higgs model. We show that the Killing spinor equations admit
rotationally symmetric vortex solutions with asymptotically conical geometry
which preserve half of the supersymmetry.Comment: 26 pages, LaTeX2
No tradeoff between confidentiality and performance: An analysis on H.264/SVC partial encryption
Agency for Science, Technology and Research (A*STAR
Correlated two-electron transport: a principle for a novel charge pump
By considering a correlated two-electron transport process (TET) and using a
diagrammatic analysis within the Keldysh nonequilibrium Green's function
formalism, we discuss a novel charge pump by which carriers are pumped from a
contact with low chemical potential to another contact with a higher potential.
The TET process involves two correlated incident electrons scattering and
exchanging energy with each other. The process can significantly affect charge
current density and it involves high empty states and/or low filled states of
the Fermi liquid of the leads.Comment: 4 pages, 4 figures, revte
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Basaltic and Solution Reference Materials for Iron, Copper and Zinc Isotope Measurements
Iron, Cu and Zn stable isotope systems are applied in constraining a variety of geochemical and environmental processes. Secondary reference materials have been developed by the Institute of Geology, Chinese Academy of Geological Sciences (CAGS), in collaboration with other participating laboratories, comprising three solutions (CAGS-Fe, CAGS-Cu and CAGS-Zn) and one basalt (CAGS-Basalt). These materials exhibit sufficient homogeneity and stability for application in Fe, Cu and Zn isotopic ratio determinations. Reference values were determined by inter-laboratory analytical comparisons involving up to eight participating laboratories employing MC-ICP-MS techniques, based on the unweighted means of submitted results. Isotopic compositions are reported in per mil notation, based on reference materials IRMM-014 for Fe, NIST SRM 976 for Cu and IRMM-3702 for Zn. Respective reference values of CAGS-Fe, CAGS-Cu and CAGS-Zn solutions are as follows: δ56Fe = 0.83 ± 0.06 and δ57Fe = 1.20 ± 0.12, δ65Cu = 0.57 ± 0.05, and δ66Zn = -0.79 ± 0.12 and δ68Zn = -1.65 ± 0.24, respectively. Those of CAGS-Basalt are δ56Fe = 0.15 ± 0.05, δ57Fe = 0.22 ± 0.05, δ65Cu = 0.12 ± 0.07, δ66Zn = 0.17 ± 0.11, and δ68Zn = 0.34 ± 0.21 (2s)
Relativistic close coupling calculations for photoionization and recombination of Ne-like Fe XVII
Relativistic and channel coupling effects in photoionization and unified
electronic recombination of Fe XVII are demonstrated with an extensive 60-level
close coupling calculation using the Breit-Pauli R-matrix method.
Photoionization and (e + ion) recombination calculations are carried out for
the total and the level-specific cross sections, including the ground and
several hundred excited bound levels of Fe XVII (up to fine structure levels
with n = 10). The unified (e + ion) recombination calculations for (e + Fe
XVIII --> Fe XVII) include both the non-resonant and resonant recombination
(`radiative' and `dielectronic recombination' -- RR and DR). The low-energy and
the high energy cross sections are compared from: (i) a 3-level calculation
with 2s^2p^5 (^2P^o_{1/2,3/2}) and 2s2p^6 (^2S_{1/2}), and (ii) the first
60-level calculation with \Delta n > 0 coupled channels with spectroscopic
2s^2p^5, 2s2p^6, 2s^22p^4 3s, 3p, 3d, configurations, and a number of
correlation configurations. Strong channel coupling effects are demonstrated
throughout the energy ranges considered, in particular via giant
photoexcitation-of-core (PEC) resonances due to L-M shell dipole transition
arrays 2p^5 --> 2p^4 3s, 3d in Fe XIII that enhance effective cross sections by
orders of magnitude. Comparison is made with previous theoretical and
experimental works on photoionization and recombination that considered the
relatively small low-energy region (i), and the weaker \Delta n = 0 couplings.
While the 3-level results are inadequate, the present 60-level results should
provide reasonably complete and accurate datasets for both photoionization and
(e + ion) recombination of Fe~XVII in laboratory and astrophysical plasmas.Comment: 19 pages, 8 figures, Phys. Rev. A (submitted
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