104,918 research outputs found
Ideal two-dimensional electron systems with a giant Rashba-type spin splitting in real materials: surfaces of bismuth tellurohalides
Spintronics is aimed at active controlling and manipulating the spin degrees
of freedom in semiconductor devices. A promising way to achieve this goal is to
make use of the tunable Rashba effect that relies on the spin-orbit interaction
(SOI) in a two-dimensional (2D) electron system immersed in an
inversion-asymmetric environment. The SOI induced spin-splitting of the
2D-electron state provides a basis for many theoretically proposed spintronic
devices. However, the lack of semiconductors with large Rashba effect hinders
realization of these devices in actual practice. Here we report on a giant
Rashba-type spin splitting in 2D electron systems which reside at
tellurium-terminated surfaces of bismuth tellurohalides. Among these
semiconductors, BiTeCl stands out for its isotropic metallic surface-state band
with the Gamma-point energy lying deep inside the bulk band gap. The giant
spin-splitting of this band ensures a substantial spin asymmetry of the
inelastic mean free path of quasiparticles with different spin orientations.Comment: 12 pages, 5 figure
Choosing a density functional for static molecular polarizabilities
Coupled-cluster calculations of static electronic dipole polarizabilities for
145 organic molecules are performed to create a reference data set. The
molecules are composed from carbon, hydrogen, nitrogen, oxygen, fluorine,
sulfur, chlorine, and bromine atoms. They range in size from triatomics to 14
atoms. The Hartree-Fock and 2nd-order M{\o}ller-Plesset methods and 34 density
functionals, including local functionals, global hybrid functionals, and
range-separated functionals of the long-range-corrected and screened-exchange
varieties, are tested against this data set. On the basis of the test results,
detailed recommendations are made for selecting density functionals for
polarizability computations on relatively small organic molecules
Description of bulk observables in Au+Au collisions at top RHIC energy in the integrated HydroKinetic Model
The results on the main bulk observables obtained in the simulations within
the integrated hydrokinetic model (iHKM) of Au+Au collisions at the RHIC energy
GeV are presented along with the corresponding experimental
data from the STAR and the PHENIX collaborations. The simulations include all
the stages of the collision process: formation of the initial state, its
gradual thermalization and hydrodynamization, viscous relativistic
hydro-evolution, system's hadronization and particlization, and, finally, an
expansion of the interacting hadron-resonance gas. The model gives a
satisfactory description of charged-particle multiplicities, particle number
ratios, transverse momentum spectra for pions, kaons, protons and antiprotons,
charged-particle coefficients, and femtoscopy radii at all collision
centralities. It is demonstrated how one can estimate the times of the pion and
kaon maximal emission from the femto-scales.Comment: 17 pages, 14 figure
Symmetry and Intertwining Operators for the Nonlocal Gross-Pitaevskii Equation
We consider the symmetry properties of an integro-differential
multidimensional Gross-Pitaevskii equation with a nonlocal nonlinear (cubic)
term in the context of symmetry analysis using the formalism of semiclassical
asymptotics. This yields a semiclassically reduced nonlocal Gross-Pitaevskii
equation, which can be treated as a nearly linear equation, to determine the
principal term of the semiclassical asymptotic solution. Our main result is an
approach which allows one to construct a class of symmetry operators for the
reduced Gross-Pitaevskii equation. These symmetry operators are determined by
linear relations including intertwining operators and additional algebraic
conditions. The basic ideas are illustrated with a 1D reduced Gross-Pitaevskii
equation. The symmetry operators are found explicitly, and the corresponding
families of exact solutions are obtained
Description of bulk observables in Au+Au collisions at top RHIC energy in the integrated HydroKinetic Model
The results on the main bulk observables obtained in the simulations within
the integrated hydrokinetic model (iHKM) of Au+Au collisions at the RHIC energy
GeV are presented along with the corresponding experimental
data from the STAR and the PHENIX collaborations. The simulations include all
the stages of the collision process: formation of the initial state, its
gradual thermalization and hydrodynamization, viscous relativistic
hydro-evolution, system's hadronization and particlization, and, finally, an
expansion of the interacting hadron-resonance gas. The model gives a
satisfactory description of charged-particle multiplicities, particle number
ratios, transverse momentum spectra for pions, kaons, protons and antiprotons,
charged-particle coefficients, and femtoscopy radii at all collision
centralities. It is demonstrated how one can estimate the times of the pion and
kaon maximal emission from the femto-scales.Comment: 17 pages, 14 figure
Branching Ratios for the Decay of
Based on measurements the branching ratios for the decay of the recently
discovered dibaryon resonance into two-pion production channels and
into the channel are evaluated. Possibilities for a decay into the
isoscalar single-pion channel are discussed. Finally also the electromagnetic
decay of is considered
Gravitational parity anomaly with and without boundaries
In this paper we consider gravitational parity anomaly in three and four
dimensions. We start with a re-computation of this anomaly on a 3D manifold
without boundaries and with a critical comparison of our results to the
previous calculations. Then we compute the anomaly on 4D manifolds with
boundaries with local bag boundary conditions. We find, that gravitational
parity anomaly is localized on the boundary and contains a gravitational
Chern-Simons terms together with a term depending of the extrinsic curvature.
We also discuss the main properties of the anomaly, as the conformal
invariance, relations between 3D and 4D anomalies, etc.Comment: 16 pages, final version, accepted for publication in JHE
Darboux transformations for differential operators on the superline
We give a full description of Darboux transformations of any order for
arbitrary (nondegenerate) differential operators on the superline. We show that
every Darboux transformation of such operators factorizes into elementary
Darboux transformations of order one. Similar statement holds for operators on
the ordinary line
Examination of the Nature of the ABC Effect
Recently it has been shown by exclusive and kinematically complete
experiments that the appearance of a narrow resonance structure in
double-pionic fusion reactions is strictly correlated with the appearance of
the so-called ABC effect, which denotes a pronounced low-mass enhancement in
the -invariant mass spectrum. Whereas the resonance structure got its
explanation by the dibaryonic resonance, a satisfactory explanation
for the ABC effect is still pending. In this paper we discuss possible
explanations of the ABC effect and their consequences for the internal
structure of the dibaryon
Conformal Newton-Hooke symmetry of Pais-Uhlenbeck oscillator
It is demonstrated that the Pais-Uhlenbeck oscillator in arbitrary dimension
enjoys the l-conformal Newton-Hooke symmetry provided frequencies of
oscillation form the arithmetic sequence omega_k=(2k-1) omega_1, where
k=1,...,n, and l is the half-integer (2n-1)/2. The model is shown to be
maximally superintegrable. A link to n decoupled isotropic oscillators is
discussed and an interplay between the l-conformal Newton-Hooke symmetry and
symmetries characterizing each individual isotropic oscillator is analyzed.Comment: V3:Introduction extended, one reference added. The version to appear
in NP
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