2,567 research outputs found
Isospin violation in via hadronic loops
In this work, we study the isospin-violating decay of
and quantify the electromagnetic (EM) transitions and intermediate meson
exchanges as two major sources of the decay mechanisms. In the EM decays, the
present datum status allows a good constraint on the EM decay form factor in
the vector meson dominance (VMD) model, and it turns out that the EM transition
can only account for about of the branching ratio for . The intermediate meson exchanges, (intermediate
interaction via exchanges), (intermediate
rescattering via kaon exchanges), and
(intermediate rescattering via exchanges), which evade the
naive Okubo-Zweig-Iizuka (OZI) rule, serve as another important contribution to
the isospin violations. They are evaluated with effective Lagrangians where
explicit constraints from experiment can be applied. Combining these three
contributions, we obtain results in good agreement with the experimental data.
This approach is also extended to , where
we find contributions from the , and
loops are negligibly small, and the isospin violation is
likely to be dominated by the EM transition.Comment: Revised version resubmitted to PRD; Additional loop contributions
included; Conclusion unchange
On Exact Bayesian Credible Sets for Classification and Pattern Recognition
The current definition of a Bayesian credible set cannot, in general, achieve
an arbitrarily preassigned credible level. This drawback is particularly acute
for classification problems, where there are only a finite number of achievable
credible levels. As a result, there is as of today no general way to construct
an exact credible set for classification. In this paper, we introduce a
generalized credible set that can achieve any preassigned credible level. The
key insight is a simple connection between the Bayesian highest posterior
density credible set and the Neyman--Pearson lemma, which, as far as we know,
hasn't been noticed before. Using this connection, we introduce a randomized
decision rule to fill the gaps among the discrete credible levels. Accompanying
this methodology, we also develop the Steering Wheel Plot to represent the
credible set, which is useful in visualizing the uncertainty in classification.
By developing the exact credible set for discrete parameters, we make the
theory of Bayesian inference more complete.Comment: 16 pages, 6 figure
The meson-exchange model for the interaction
In the present work, we apply the one-boson-exchange potential (OBEP) model
to investigate the possibility of Y(2175) and as bound states of
and respectively.
We consider the effective potential from the pseudoscalar -exchange and
-exchange, the scalar -exchange, and the vector
-exchange and -exchange. The and meson exchange
potential is repulsive force for the state and attractive for .
The results depend very sensitively on the cutoff parameter of the
-exchange () and least sensitively on that of the
-exchange (). Our result suggests the possible
interpretation of Y(2175) and as the bound states of
and respectively
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