2,183 research outputs found
A widely tunable few electron droplet
Quasi-static transport measurements are employed to characterize a few
electron quantum dot electrostatically defined in a GaAs/AlGaAs
heterostructure. The gate geometry allows observations on one and the same
electron droplet within a wide range of coupling strengths to the leads. The
weak coupling regime is described by discrete quantum states. At strong
interaction with the leads Kondo phenomena are observed as a function of a
magnetic field. By varying gate voltages the electron droplet can, in addition,
be distorted into a double quantum dot with a strong interdot tunnel coupling
while keeping track of the number of trapped electrons.Comment: 11 pages, 5 figure
Hopping conductivity in heavily doped n-type GaAs layers in the quantum Hall effect regime
We investigate the magnetoresistance of epitaxially grown, heavily doped
n-type GaAs layers with thickness (40-50 nm) larger than the electronic mean
free path (23 nm). The temperature dependence of the dissipative resistance
R_{xx} in the quantum Hall effect regime can be well described by a hopping law
(R_{xx} \propto exp{-(T_0/T)^p}) with p=0.6. We discuss this result in terms of
variable range hopping in a Coulomb gap together with a dependence of the
electron localization length on the energy in the gap. The value of the
exponent p>0.5 shows that electron-electron interactions have to be taken into
account in order to explain the occurrence of the quantum Hall effect in these
samples, which have a three-dimensional single electron density of states.Comment: 5 pages, 2 figures, 1 tabl
Production of Stop, Sbottom, and Stau at LEP2
We present a comprehensive study of pair production and decay of stops,
sbottoms, and staus in annihilation at LEP2. We give numerical
predictions within the Minimal Supersymmetric Standard Model for cross sections
and decay rates, and discuss the important signatures. In the case of stau
production we also study the polarization of the tau in the decays stau_1 ->
tau + neutralino_{1,2}.Comment: 15 pages, LateX, 13 figures appended as uuencoded PS-file. LateX file
and figures are also available via anonymous ftp at
ftp://info.oeaw.ac.at/pub/hephy-pub/64
Scalar Top Quark Production at Colliders
We discuss the production of stops at a collider. We present
numerical predictions for the cross sections within the Minimal Supersymmetric
Standard Model. In particular we consider stop production near and .Comment: 6 pages LaTeX including 5 figures. Talk presented by W. Porod at the
"Workshop on Physics at the First Muon Collider and the Front End of a Muon
Collider", November 6 - 9, 1997, FNAL, Batavia, Illinois, US
Phenomenology of stops, sbottoms, tau-sneutrinos, and staus at an e+e- Linear Collider
We discuss production and decays of stops, sbottoms, tau-sneutrinos, and
staus in e+e- annihilation in the energy range \sqrt{s} = 0.5-1 TeV. We present
numerical predictions within the Minimal Supersymmetric Standard Model for
cross sections and decay rates, including one-loop radiative corrections as
well as initial state radiation. We also study the importance of beam
polarization for the determination of the underlying SUSY parameters. Moreover,
we make a comparison of the potential to study squarks and sleptons of the 3rd
generation between Tevatron, LHC, and Linear Collider.Comment: Version to be published in EPJdirec
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