16,462 research outputs found
A Note on Schwinger Mechanism and a Nonabelian Instability in a Nonabelian Plasma
We point out that there is a nonabelian instability for a nonabelian plasma
which does not allow both for a net nonzero color charge and the existence of
field configurations which are coherent over a volume whose size is
determined by the chemical potential. The basic process which leads to this
result is the Schwinger decay of chromoelectric fields, for the case where the
field arises from commutators of constant potentials, rather than as the curl
of spacetime dependent potentials. In terms of the fields, instability is
obtained when Tr(DF)^2 > 0.Comment: 14 pages, 6 figure
Biexciton recombination rates in self-assembled quantum dots
The radiative recombination rates of interacting electron-hole pairs in a
quantum dot are strongly affected by quantum correlations among electrons and
holes in the dot. Recent measurements of the biexciton recombination rate in
single self-assembled quantum dots have found values spanning from two times
the single exciton recombination rate to values well below the exciton decay
rate. In this paper, a Feynman path-integral formulation is developed to
calculate recombination rates including thermal and many-body effects. Using
real-space Monte Carlo integration, the path-integral expressions for realistic
three-dimensional models of InGaAs/GaAs, CdSe/ZnSe, and InP/InGaP dots are
evaluated, including anisotropic effective masses. Depending on size, radiative
rates of typical dots lie in the regime between strong and intermediate
confinement. The results compare favorably to recent experiments and
calculations on related dot systems. Configuration interaction calculations
using uncorrelated basis sets are found to be severely limited in calculating
decay rates.Comment: 11 pages, 4 figure
Phosphate mediated changes in phospholipids in Neurospora crassa.
Phosphate mediated changes in phospholipids in Neurospora crassa
Influence of bond orientational order on the switching time of ferroelectric smectics
We report studies of the bulk switching time as a function of temperature in the chiral smectic C (C∗ ) and chiral smectic I (I∗) phases of 4-(2-methylbutyl) phenyl 4'-(octyloxy)-(1,1')-biphenyl-4-carboxylate (8OSI) which shows a continuous evolution from the fluid C∗ to the hexatic I∗ phase. The thermal variation of the switching time is found (to our knowledge for the first time) to scale remarkably well with the hexatic order parameter for the two phases determined experimentally by Brock et al for 8OSI, the racemic form of 8OSI. Similar correlation is observed in the case of 8SI∗, the alkyl analog of 8OSI∗, which shows a first order C∗-I∗ transition
Phosphate mediated changes in fatty acid composition in Neurospora crassa.
Phosphate mediated changes in fatty acid composition in Neurospora crassa
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