2,254 research outputs found
Division subspaces and integrable kernels
In this note we prove that the reproducing kernel of a Hilbert space
satisfying the division property has integrable form, is locally of trace
class, and the Hilbert space itself is a Hilbert space of holomorphic
functions.Comment: 11 page
High-frequency oscillations in low-dimensional conductors and semiconductor superlattices induced by current in stack direction
A narrow energy band of the electronic spectrum in some direction in
low-dimensional crystals may lead to a negative differential conductance and
N-shaped I-V curve that results in an instability of the uniform stationary
state. A well-known stable solution for such a system is a state with electric
field domain. We have found a uniform stable solution in the region of negative
differential conductance. This solution describes uniform high-frequency
voltage oscillations. Frequency of the oscillation is determined by antenna
properties of the system. The results are applicable also to semiconductor
superlattices.Comment: 8 pages, 3 figure
Stable Spin Precession at one Half of Equilibrium Magnetization in Superfluid 3He-B
New stable modes of spin precession have been observed in superfluid 3He-B.
These dynamical order parameter states include precession with a magnetization
S=pS_{eq} which is different from the equilibrium value S_{eq}. We have
identified modes with p=1, 1/2 and \approx 0. The p=1/2 mode is the second
member of phase correlated states of a spin superfluid. The new states can be
excited in the temperature range 1-T/T_c \lesssim 0.02 where the energy
barriers between the different local minima of the spin-orbit energy are small.
They are stable in CW NMR due to low dissipation close to T_c.Comment: submitted to Physical Review Letters, 4 pages, revtex, 4 Figures in
ftp://boojum.hut.fi/pub/publications/lowtemp/LTL-96005.p
QCD Heat Kernel in Covariant Gauge
We report the calculation of the fourth coefficient in an expansion of the
heat kernel of a non-minimal, non-abelian kinetic operator in an arbitrary
background gauge in arbitrary space-time dimension. The fourth coefficient is
shown to bring a nontrivial gauge dependence due to the contribution of the
lowest order off-shell gauge invariant structure.Comment: 6 pages + title page, standart LaTe
Phonons in magnon superfluid and symmetry breaking field
Recent experiments [1],[2] which measured the spectrum of the Goldstone
collective mode of coherently precessing state in 3He-B are discussed using the
presentation of the coherent spin precession in terms of the Bose-Einstein
condensation of magnons. The mass in the spectrum of the Goldstone boson --
phonon in the superfluid magnon liquid -- is induced by the symmetry breaking
field, which is played by the RF magnetic fieldComment: 2 pages, JETP Letters style, no figures, version accepted in JETP
Letter
Exciton spin decay modified by strong electron-hole exchange interaction
We study exciton spin decay in the regime of strong electron-hole exchange
interaction. In this regime the electron spin precession is restricted within a
sector formed by the external magnetic field and the effective exchange fields
triggered by random spin flips of the hole. Using Hanle effect measurements, we
demonstrate that this mechanism dominates our experiments in CdTe/(Cd,Mg)Te
quantum wells. The calculations provide a consistent description of the
experimental results, which is supported by independent measurements of the
parameters entering the model.Comment: 5 pages, 3 figure
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