405 research outputs found
Boson Stars with Large Self-interaction in (2+1) dimensions: an Exact Solution
An exact solution for a nonrotating boson star in (2+1) dimensional gravity
with a negative cosmological constant is found. The relations among mass,
particle number, and radius of the (2+1) dimensional boson star are shown.Comment: 16 pages, 7 figures, needs REVTeX (2nd revised version
Deconstructing Scalar QED at Zero and Finite Temperature
We calculate the effective potential for the WLPNGB in a world with a
circular latticized extra dimension. The mass of the WLPNGB is calculated from
the one-loop quantum effect of scalar fields at zero and finite temperature. We
show that a series expansion by the modified Bessel functions is useful to
calculate the one-loop effective potentials.Comment: 12 pages, 2 figures. RevTeX
Design of a semiconductor ferromagnet in a quantum dot artificial crystal
We present the theoretical design of quantum dot (QD) artificial
ferromagnetic crystals. The electronic structure calculations based on local
spin density approximation (LSDA) show that our designed QD artificial crystal
from a structure comprising the crossing 0.104-micrometer-wide InAs quantum
wires (an effective Kagome lattice) has flat band characteristics. Our examined
QD artificial crystal has the ferromagnetic ground state when the flat band is
half-filled, even though it contains no magnetic elements. The ferromagnetic
and the paramagnetic state can be freely switched by changing the electron
filling via a gate voltage.Comment: 12 pages, 3 figures included. For related information, visit
http://www.brl.ntt.co.jp/people/tamura
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