53,611 research outputs found
On intertwining operators and finite automorphism groups of vertex operator algebras
Let V be a simple vertex operator algebra and G a finite automorphism group.
We give a construction of intertwining operators for irreducible V^G-modules
which occur as submodules of irreducible V-modules by using intertwining
operators for V. We also determine some fusion rules for a vertex operator
algebra as an application.Comment: 26 page
Fast Rise of "Neptune-Size" Planets () from to days -- Statistics of Kepler Planet Candidates Up to
We infer the period () and size () distribution of Kepler transiting
planet candidates with and days hosted by
solar-type stars. The planet detection efficiency is computed by using measured
noise and the observed timespans of the light curves for Kepler
target stars. We focus on deriving the shape of planet period and radius
distribution functions. We find that for orbital period days, the planet
frequency d/dP for "Neptune-size" planets () increases with period as . In contrast,
d/dP for "super-Earth-size" () as well as
"Earth-size" () planets are consistent with a nearly flat
distribution as a function of period ( and , respectively), and the normalizations are remarkably similar
(within a factor of at days). Planet size distribution evolves
with period, and generally the relative fractions for big planets () increase with period. The shape of the distribution function is
not sensitive to changes in selection criteria of the sample. The implied
nearly flat or rising planet frequency at long period appears to be in tension
with the sharp decline at days in planet frequency for low mass
planets (planet mass ) recently suggested by HARPS
survey. Within days, the cumulative frequencies for Earth-size and
super-Earth-size planets are remarkably similar ( and ), while
Neptune-size and Jupiter-size planets are , and ,
respectively. A major potential uncertainty arises from the unphysical impact
parameter distribution of the candidates.Comment: Accepted by Ap
Effective tuning of exciton polarization splitting in coupled quantum dots
The polarization splitting of the exciton ground state in two laterally
coupled quantum dots under an in-plane electric field is investigated and its
effective tuning is designed. It is found that there are significant Stark
effect and anticrossing in energy levels. Due to coupling between inter- and
intra-dot states, the absolute value of polarization splitting is significantly
reduced, and it could be tuned to zero by the electric field for proper
inter-dot separations. Our scheme is interesting for the research on the
quantum dots-based entangled-photon source.Comment: 4 pages, 2 figures, to appear in Appl. Phys. Let
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