49,440 research outputs found
Annihilation Type Radiative Decays of Meson in Perturbative QCD Approach
With the perturbative QCD approach based on factorization, we study the
pure annihilation type radiative decays and . We find that the branching ratio of is
, which is too small to be measured
in the current factories of BaBar and Belle. The branching ratio of is , which is just
at the corner of being observable in the factories. A larger branching
ratio is also predicted.
These decay modes will help us testing the standard model and searching for new
physics signals.Comment: 4 pages, revtex, with 1 eps figur
Density oscillations in trapped dipolar condensates
We investigated the ground state wave function and free expansion of a
trapped dipolar condensate. We find that dipolar interaction may induce both
biconcave and dumbbell density profiles in, respectively, the pancake- and
cigar-shaped traps. On the parameter plane of the interaction strengths, the
density oscillation occurs only when the interaction parameters fall into
certain isolated areas. The relation between the positions of these areas and
the trap geometry is explored. By studying the free expansion of the condensate
with density oscillation, we show that the density oscillation is detectable
from the time-of-flight image.Comment: 7 pages, 9 figure
Consistent Estimation of Mixed Memberships with Successive Projections
This paper considers the parameter estimation problem in Mixed Membership
Stochastic Block Model (MMSB), which is a quite general instance of random
graph model allowing for overlapping community structure. We present the new
algorithm successive projection overlapping clustering (SPOC) which combines
the ideas of spectral clustering and geometric approach for separable
non-negative matrix factorization. The proposed algorithm is provably
consistent under MMSB with general conditions on the parameters of the model.
SPOC is also shown to perform well experimentally in comparison to other
algorithms
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