5,589 research outputs found
Finite size and finite temperature studies of the spin chain
We study a quantum spin chain invariant by the superalgebra . We
derived non-linear integral equations for the row-to-row transfer matrix
eigenvalue in order to analyze its finite size scaling behaviour and we
determined its central charge. We have also studied the thermodynamical
properties of the obtained spin chain via the non-linear integral equations for
the quantum transfer matrix eigenvalue. We numerically solved these NLIE and
evaluated the specific heat and magnetic susceptibility. The analytical low
temperature analysis was performed providing a different value for the
effective central charge. The computed values are in agreement with the
numerical predictions in the literature.Comment: 26 pages, 2 figure
Carrier relaxation due to electron-electron interaction in coupled double quantum well structures
We calculate the electron-electron interaction induced energy-dependent
inelastic carrier relaxation rate in doped semiconductor coupled double quantum
well nanostructures within the two subband approximation at zero temperature.
In particular, we calculate, using many-body theory, the imaginary part of the
full self-energy matrix by expanding in the dynamically RPA screened Coulomb
interaction, obtaining the intrasubband and intersubband electron relaxation
rates in the ground and excited subbands as a function of electron energy. We
separate out the single particle and the collective excitation contributions,
and comment on the effects of structural asymmetry in the quantum well on the
relaxation rate. Effects of dynamical screening and Fermi statistics are
automatically included in our many body formalism rather than being
incorporated in an ad-hoc manner as one must do in the Boltzman theory.Comment: 26 pages, 5 figure
Effects of an extra gauge boson on the top quark decay
The effects of an extra gauge boson with family nonuniversal fermion
couplings on the rare top quark decay gamma10^{-8}m_{Z'}=500Z'B(t --> c
\gamma)\sim 10^{-6}m_{Z'}=1$ TeV.Comment: New paragraphs included to clarify our results, conclusion remains
unchange
Tunneling effects on impurity spectral function in coupled asymmetric quantum wires
The impurity spectral function is studied in coupled double quantum wires at
finite temperatures. Simple anisotropy in the confinement direction of the
wires leads to finite non-diagonal elements of the impurity spectral function
matrix. These non-diagonal elements are responsible for tunneling effects and
result in pronounced extra peak in the impurity spectral function up to
temperatures as high as 20 K.Comment: Accepted in Phys. Rev.
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