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1.
S. J. Cheng W. Sheng P. Hawrylak S. Raymond S. Studenikin A. Sachrajda Z. Wasilewski A. Babinski M. Potemski G. Ortner M. Bayer 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):211
We present results of calculations and experiments on electron–hole complexes in InGaAs/GaAs self-assembled quantum dots in high magnetic field (B). Due to hidden symmetries, the chemical potential of an N-exciton system at special B fields becomes insensitive to the exciton number as well as the magnetic field. This results in plateau regions of high intensity in measured magneto-PL spectrum. Theoretical calculations using exact diagonalization techniques successfully explain the measured magneto-photoluminescence spectrum with B fields up to 28 T. 相似文献
2.
JOSEF MÁLEK JINDŘICH NEČAS K. R. RAJAGOPAL 《Archive for Rational Mechanics and Analysis》2002,165(3):243-269
To describe the flows of fluids over a wide range of pressures, it is necessary to take into account the fact that the viscosity
of the fluid depends on the pressure. That the viscosity depends on the pressure has been verified by numerous careful experiments.
While the existence of solutions local-in-time to the equations governing the flows of such fluids are available for small,
special data and rather unrealistic dependence of the viscosity on the pressure, no global existence results are in place.
Our interest here is to establish the existence of weak solutions for spatially periodic three-dimensional flows that are
global in time, for a large class of physically meaningful viscosity-pressure relationships.
(Accepted May 1, 2002) Published online November 15, 2002
Communicated by S. S. ANTMAN 相似文献
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We show that knowledge of the valence quark distribution of a proton at one value of q2, enables one to calculate a contribution to the difference between the distribution of anti-up quarks and anti-down quarks in the sea of the proton at higher values of q2. This difference can be expressed as a linear combination of the structure functions F1, for νp → νX and e?p → e?p (for which one knows the q2 behaviour of the moments) and for (for which one knows the q2 behaviour of the odd moments). The calculable contribution involves a non-trivial continuation of the even (odd) moments of the neutral (charged) current structure functions to odd (even) moments. We calculate this contribution and although we find that its sign is negative we point out that this cannot be interpreted as a consequences of the Pauli exclusion principle. We discuss the constraints our results impose on antiquark distributions. 相似文献
6.
C.T. Sachrajda 《Physics letters. [Part B]》1978,76(1):100-104
We calculate the cross section for the process quark + quark → quark (with large transverse momentum) + anything, up to order g6 in the cross section and in the leading-logarithm approximation. The result is suggestive of a simple ansatz for the calculation of the asymptotic behaviour of cross sections for the production of particles or jets with large transverse momenta. 相似文献
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There is currently a large effort to explore spin-orbit effects in semiconductor structures with the ultimate goal of manipulating electron spins with gates. A search for materials with large spin-orbit coupling is therefore important. We report results of a study of spin-orbit effects in a strained InGaAs/InP quantum well. The spin-orbit relaxation time, determined from the weak antilocalization effect, was found to depend nonmonotonically on gate voltage. The spin-orbit scattering rate had a maximum value of 5×1010 s?1 at an electron density of n=3×1015 m?2. The scattering rate decreased from this for both increasing and decreasing densities. The smallest measured value was approximately 109 s?1 at an electron concentration of n=6×1015 m?2. This behavior could not be explained by either the Rashba or the bulk Dresselhaus mechanisms but is attributed to asymmetry or strain effects at dissimilar quantum well interfaces. 相似文献
8.
A waveguide in integrated optics is defined by its refractiveindex. The guide is assumed to be invariant in the propagationdirection while in the transverse direction it is supposed tobe a compact perturbation of an unbounded stratified medium.We are interested in the modes guided by this device, whichare waves with a transverse energy confined in a neighbourhoodof the perturbation. Our goal is to analyse the existence of such guided modes. Underthe assumptions of weak guidance the problem reduces to a two-dimensionaleigenvalue problem for a scalar field. The associated operatoris unbounded, selfadjoint, and bounded from below. Its spectrumconsists of the discrete spectrum corresponding to the guidedmodes and of the essential spectrum corresponding to the radiationmodes. We present existence results of guided modes and an asymptoticstudy at high frequencies, which shows that contrarily to thecase of optical fibers, the number of guided modes can remainbounded. The major tools are the min-max principle and comparisonof results between different eigenvalue problems. The originalityof the present study lies in the stratified character of theunbounded reference medium. 相似文献
9.
We demonstrate that the cross section for the radiation of soft gluons in quantum chromodynamics does not obey a Poisson distribution (even when the colours of the gluons are summed over.) This implies that any cancellation of infrared divergences between radiative corrections from real and virtual gluons in QCD must be more complicated than in QED. We present an example of such a cancellation. 相似文献
10.
It is argued that the sum of the leading terms to each order in the coupling constant in massive Q.E.D. at fixed angle leads to the elastic cross-section dσ/dt = A(θ)s?2exp (a ln2s + b(θ)lns). This gives good agreement with the data for wide angle proton-proton scattering. 相似文献