55,152 research outputs found
A case in favor of the
Using an interaction extracted from the local hidden gauge Lagrangians, which
brings together vector and pseudoscalar mesons, and the coupled channels (s-wave), (d-wave), (s-wave) and (d-wave),
we look in the region of MeV and we find two resonances
dynamically generated by the interaction of these channels, which are naturally
associated to the and . The appears neatly as a pole in the complex plane. The free parameters of
the theory are chosen to fit the (d-wave) data. Both the real and
imaginary parts of the amplitude vanish in our approach in the vicinity
of this resonance, similarly to what happens in experimental determinations,
what makes this signal very weak in this channel. This feature could explain
why this resonance does not show up in some experimental analyses, but the
situation is analogous to that of the resonance, the second scalar
meson after the in the (d-wave) amplitude. The
unitary coupled channel approach followed here, in connection with the
experimental data, leads automatically to a pole in the 1700 MeV region and
makes this second resonance unavoidable
Combining information from independent sources through confidence distributions
This paper develops new methodology, together with related theories, for
combining information from independent studies through confidence
distributions. A formal definition of a confidence distribution and its
asymptotic counterpart (i.e., asymptotic confidence distribution) are given and
illustrated in the context of combining information. Two general combination
methods are developed: the first along the lines of combining p-values, with
some notable differences in regard to optimality of Bahadur type efficiency;
the second by multiplying and normalizing confidence densities. The latter
approach is inspired by the common approach of multiplying likelihood functions
for combining parametric information. The paper also develops adaptive
combining methods, with supporting asymptotic theory which should be of
practical interest. The key point of the adaptive development is that the
methods attempt to combine only the correct information, downweighting or
excluding studies containing little or wrong information about the true
parameter of interest. The combination methodologies are illustrated in
simulated and real data examples with a variety of applications.Comment: Published at http://dx.doi.org/10.1214/009053604000001084 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Confidence distribution (CD) -- distribution estimator of a parameter
The notion of confidence distribution (CD), an entirely frequentist concept,
is in essence a Neymanian interpretation of Fisher's Fiducial distribution. It
contains information related to every kind of frequentist inference. In this
article, a CD is viewed as a distribution estimator of a parameter. This leads
naturally to consideration of the information contained in CD, comparison of
CDs and optimal CDs, and connection of the CD concept to the (profile)
likelihood function. A formal development of a multiparameter CD is also
presented.Comment: Published at http://dx.doi.org/10.1214/074921707000000102 in the IMS
Lecture Notes Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
The decay of the and its nature as a molecule
We investigate the decay of with the assumption
that the is dynamically generated from the
interaction. In addition to the tree level diagrams that proceed via , we take into account also the final
state interactions of and . The
partial decay width and mass distributions of are
evaluated. We get a value for the partial decay width which, within errors, is
in fair agreement with the experimental result. The contribution from the tree
level diagrams is dominant, but the final state interactions have effects in
the mass distributions. The predicted mass distributions are significantly
different from phase space and tied to the nature of the
state.Comment: Published versio
, and the scalar bound state
We study the decay to based on the chiral unitary
model that generates the X(3720) resonance, and make predictions for the invariant mass distribution. From the shape of the distribution, the
existence of the resonance below threshold could be induced. We also predict
the rate of production of the X(3720) resonance to the mass
distribution with no free parameters.Comment: 9 pages, 17 figure
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