15,577 research outputs found
Heterotic Vortex Strings
We determine the low-energy N=(0,2) worldsheet dynamics of vortex strings in
a large class of non-Abelian N=1 supersymmetric gauge theories.Comment: 44 pages, 3 figures. v2: typos corrected, reference adde
Electron Transfer in Donor-Acceptor Systems: Many-Particle Effects and Influence of Electronic Correlations
We investigate electron transfer processes in donor-acceptor systems with a
coupling of the electronic degrees of freedom to a common bosonic bath. The
model allows to study many-particle effects and the influence of the local
Coulomb interaction U between electrons on donor and acceptor sites. Using the
non-perturbative numerical renormalization group approach we find distinct
differences between the electron transfer characteristics in the single- and
two-particle subspaces. We calculate the critical electron-boson coupling
alpha_c as a function of and show results for density-density correlation
functions in the whole parameter space. The possibility of many-particle
(bipolaronic) and Coulomb-assisted transfer is discussed.Comment: 4 pages, 4 figure
Recommended from our members
Unraveling the Cationic and Anionic Redox Reactions in a Conventional Layered Oxide Cathode
Increasing interest in high-energy lithium-ion batteries has triggered the demand to clarify the reaction mechanism in battery cathodes during high-potential operation. However, the reaction mechanism often involves both transition-metal and oxygen activities that remain elusive. Here we report a comprehensive study of both cationic and anionic redox mechanisms of LiNiO2 nearly full delithiation. Selection of pure LiNiO2 removes the complication of multiple transition metals. Using combined X-ray absorption spectroscopy, resonant inelastic X-ray scattering, and operando differential electrochemical mass spectrometry, we are able to clarify the redox reactions of transition metals in the bulk and at the surface, reversible lattice oxygen redox, and irreversible oxygen release associated with surface reactions. Many findings presented here bring attention to different types of oxygen activities and metal-oxygen interactions in layered oxides, which are of crucial importance to the advancement of a Ni-rich layered oxide cathode for high capacity and long cycling performance
A new atmospheric aerosol phase equilibrium model (UHAERO): organic systems
In atmospheric aerosols, water and volatile inorganic and organic species are distributed between the gas and aerosol phases in accordance with thermodynamic equilibrium. Within an atmospheric particle, liquid and solid phases can exist at equilibrium. Models exist for computation of phase equilibria for inorganic/water mixtures typical of atmospheric aerosols; when organic species are present, the phase equilibrium problem is complicated by organic/water interactions as well as the potentially large number of organic species. We present here an extension of the UHAERO inorganic thermodynamic model (Amundson et al., 2006c) to organic/water systems. Phase diagrams for a number of model organic/water systems characteristic of both primary and secondary organic aerosols are computed. Also calculated are inorganic/organic/water phase diagrams that show the effect of organics on inorganic deliquescence behavior. The effect of the choice of activity coefficient model for organics on the computed phase equilibria is explored
Vortex Strings and Four-Dimensional Gauge Dynamics
We study the low-energy quantum dynamics of vortex strings in the Higgs phase
of N=2 supersymmetric QCD. The exact BPS spectrum of the stretched string is
shown to coincide with the BPS spectrum of the four-dimensional parent gauge
theory. Perturbative string excitations correspond to bound W-bosons and quarks
while the monopoles appear as kinks on the vortex string. This provides a
physical explanation for an observation by N. Dorey relating the quantum
spectra of theories in two and four dimensions.Comment: 23 pages, 1 figure. v2: Two extra appendices included: one on the
brane construction, the other describing the potential on the vortex moduli
space. Two figures added. Typos corrected and references added. v3: BPS
nature of quarks correcte
Long-range potentials and molecular resonances in an ultracold rydberg gas
We have calculated long-range molecular potentials of the ,
and symmetries between highly-excited rubidium atoms. Strong
potentials characterized by these symmetries are important in
describing interaction-induced phenomena in the excitation spectra of high
Rydberg states. Long-range molecular resonances are such phenomena and they
were first reported in S.M. Farooqi {\it et al.}, Phys. Rev. Lett. {\bf 91}
183002. One class of these resonances occurs at energies corresponding to
excited atom pairs . Such resonances are attributed to -mixing
due to Rydberg-Rydberg interactions so that otherwise forbidden molecular
transitions become allowed. We calculate molecular potentials in Hund's case
(c), use them to find the resonance lineshape and compare to experimental
results.Comment: 11 pages, 7 figure
Anomalous Nernst Effect in Dirac Semimetal Cd3As2
Dirac and Weyl semimetals display a host of novel properties. In
CdAs, the Dirac nodes lead to a protection mechanism that strongly
suppresses backscattering in zero magnetic field, resulting in ultrahigh
mobility ( 10 cm V s). In applied magnetic field,
an anomalous Nernst effect is predicted to arise from the Berry curvature
associated with the Weyl nodes. We report observation of a large anomalous
Nernst effect in CdAs. Both the anomalous Nernst signal and transport
relaxation time begin to increase rapidly at 50 K. This
suggests a close relation between the protection mechanism and the anomalous
Nernst effect. In a field, the quantum oscillations of bulk states display a
beating effect, suggesting that the Dirac nodes split into Weyl states,
allowing the Berry curvature to be observed as an anomalous Nernst effect.Comment: 13 pages, 7 figure
Slow Schroedinger dynamics of gauged vortices
Multivortex dynamics in Manton's Schroedinger--Chern--Simons variant of the
Landau-Ginzburg model of thin superconductors is studied within a moduli space
approximation. It is shown that the reduced flow on M_N, the N vortex moduli
space, is hamiltonian with respect to \omega_{L^2}, the L^2 Kaehler form on
\M_N. A purely hamiltonian discussion of the conserved momenta associated with
the euclidean symmetry of the model is given, and it is shown that the
euclidean action on (M_N,\omega_{L^2}) is not hamiltonian. It is argued that
the N=3 flow is integrable in the sense of Liouville. Asymptotic formulae for
\omega_{L^2} and the reduced Hamiltonian for large intervortex separation are
conjectured. Using these, a qualitative analysis of internal 3-vortex dynamics
is given and a spectral stability analysis of certain rotating vortex polygons
is performed. Comparison is made with the dynamics of classical fluid point
vortices and geostrophic vortices.Comment: 22 pages, 2 figure
- …