12,121 research outputs found
Weak expansiveness for actions of sofic groups
In this paper, we shall introduce -expansiveness and asymptotical
-expansiveness for actions of sofic groups. By the definitions, each
-expansive action of sofic groups is asymptotically -expansive. We show
that each expansive action of sofic groups is -expansive, and, for any given
asymptotically -expansive action of sofic groups, the entropy function (with
respect to measures) is upper semi-continuous and hence the system admits a
measure with maximal entropy.
Observe that asymptotically -expansive property was firstly introduced and
studied by Misiurewicz for -actions using the language of
topological conditional entropy. And thus in the remaining part of the paper,
we shall compare our definitions of weak expansiveness for actions of sofic
groups with the definitions given in the same spirit of Misiurewicz's ideas
when the group is amenable. It turns out that these two definitions are
equivalent in this setting.Comment: to appear in Journal of Functional Analysi
Research of the active reflector antenna using laser angle metrology system
Active reflector is one of the key technologies for constructing large
telescopes, especially for the millimeter/sub-millimeter radio telescopes. This
article introduces a new efficient laser angle metrology system for the active
reflector antenna of the large radio telescopes, with a plenty of active
reflector experiments mainly about the detecting precisions and the maintaining
of the surface shape in real time, on the 65-meter radio telescope prototype
constructed by Nanjing Institute of Astronomical Optics and Technology (NIAOT).
The test results indicate that the accuracy of the surface shape segmenting and
maintaining is up to micron dimension, and the time-response can be of the
order of minutes. Therefore, it is proved to be workable for the sub-millimeter
radio telescopes.Comment: 10 pages, 15 figure
Possible large violation in three body decays of heavy baryon
We propose a new mechanism which can introduce large asymmetries in the
phase spaces of three-body decays of heavy baryons. In this mechanism, a large
asymmetry is induced by the interference of two intermediate resonances,
which subsequently decay into two different combinations of final particles. We
apply this mechanism to the decay channel , and
find that the differential asymmetry can reach as large as , while
the regional asymmetry can reach as large as in the interference
region of the phase space.Comment: 7 pages, 2 figures, 2nd version accepted by Phys. Lett.
Localized direct CP violation in
We study the localized direct CP violation in the hadronic decays
,
including the effect caused by an interesting mechanism involving the charge
symmetry violating mixing between and . We calculate the
localized integrated direct CP violation when the low invariant mass of
[] is near . For five models of
form factors investigated, we find that the localized integrated direct CP
violation varies from -0.0170 to -0.0860 in the ranges of parameters in our
model when \,GeV. This result, especially the
sign, agrees with the experimental data and is independent of form factor
models. The new experimental data shows that the signs of the localized
integrated CP asymmetries in the regions \,GeV
and \,GeV are positive and negative,
respectively. We find that - mixing makes the localized
integrated CP asymmetry move towards the negative direction, and therefore
contributes to the sign change in those two regions. This behavior is also
model independent. We also calculate the localized integrated direct CP
violating asymmetries in the regions \,GeV and
\,GeV and find that they agree with the
experimental data in some models of form factors.Comment: 22 pages, 2 figures. arXiv admin note: text overlap with
arXiv:hep-ph/0602043, arXiv:hep-ph/0302156 by other author
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