2,213 research outputs found
Are there plasminos in superconductors?
Hot and/or dense, normal-conducting systems of relativistic fermions exhibit
a particular collective excitation, the so-called plasmino. We compute the
one-loop self-energy, the dispersion relation and the spectral density for
fermions interacting via attractive boson exchange. It is shown that plasminos
also exist in superconductors.Comment: 15 pages, 14 figures, revte
Multiexcitons confined within a sub-excitonic volume: Spectroscopic and dynamical signatures of neutral and charged biexcitons in ultrasmall semiconductor nanocrystals
The use of ultrafast gating techniques allows us to resolve both spectrally
and temporally the emission from short-lived neutral and negatively charged
biexcitons in ultrasmall (sub-10 nm) CdSe nanocrystals (nanocrystal quantum
dots). Because of forced overlap of electronic wave functions and reduced
dielectric screening, these states are characterized by giant interaction
energies of tens (neutral biexcitons) to hundreds (charged biexcitons) of meV.
Both types of biexcitons show extremely short lifetimes (from sub-100
picoseconds to sub-picosecond time scales) that rapidly shorten with decreasing
nanocrystal size. These ultrafast relaxation dynamics are explained in terms of
highly efficient nonradiative Auger recombination.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Rethinking the Properties of the Quark-Gluon Plasma at
We argue that although at asymptotically high temperatures the QGP in bulk
behaves as a gas of weakly interacting quasiparticles (modulo long-range
magnetism), at temperatures up to few times the critical temperature it
displays different properties. If the running of the QCD coupling constant
continues in the Coulomb phase till the screening length scale, it reaches the
strong coupling treshold . As a result, the Coulomb phase
supports weakly bound Coulombic s-wave , light quark and even
states.
The existence of shallow bound states dramatically increases the
quasiparticle rescattering at low energies, reducing the viscosity and thereby
explaining why heavy ion collisions at RHIC exhibit robust collective
phenomena. In conformal gauge theories at finite temperature the Coulomb
binding persists further in the strong coupling regime, as found for SUSY YM in the Maldacena regime.Comment: v2 version have one more figure and one more reference, v3 is the
same as v2 except a double-page format (the v2 had corrupted last lines on
the page
Different regimes of Forster energy transfer between an epitaxial quantum well and a proximal monolayer of semiconductor nanocrystals
We calculate the rate of non-radiative, Forster-type energy transfer (ET)
from an excited epitaxial quantum well (QW) to a proximal monolayer of
semiconductor nanocrystal quantum dots (QDs). Different electron-hole
configurations in the QW are considered as a function of temperature and
excited electron-hole density. A comparison of the theoretically determined ET
rate and QW radiative recombination rate shows that, depending on the specific
conditions, the ET rate is comparable to or even greater than the radiative
recombination rate. Such efficient Forster ET is promising for the
implementation of ET-pumped, nanocrystal QD-based light emitting devices.Comment: 14 pages, 4 figure
Hard thermal loops with a background plasma velocity
I consider the calculation of the two and three-point functions for QED at
finite temperature in the presence of a background plasma velocity. The final
expressions are consistent with Lorentz invariance, gauge invariance and
current conservation, pointing to a straightforward generalization of the hard
thermal loop formalism to this physical situation. I also give the resulting
expression for the effective action and identify the various terms.Comment: 11 pages, no figure
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