823 research outputs found
A multivariate generalization of Costa's entropy power inequality
A simple multivariate version of Costa's entropy power inequality is proved.
In particular, it is shown that if independent white Gaussian noise is added to
an arbitrary multivariate signal, the entropy power of the resulting random
variable is a multidimensional concave function of the individual variances of
the components of the signal. As a side result, we also give an expression for
the Hessian matrix of the entropy and entropy power functions with respect to
the variances of the signal components, which is an interesting result in its
own right.Comment: Proceedings of the 2008 IEEE International Symposium on Information
Theory, Toronto, ON, Canada, July 6 - 11, 200
Chiral Dynamics of scalar mesons: radiative decay and in the medium through nuclear photoproduction
In order to assess the relevance of chiral dynamics in the scalar sector we
address two recent problems: radiative decay of the , for which there are
quite recent data from Frascati, and the modification of the
properties in the nuclear medium seen through the photoproduction
in nuclei.Comment: Talk given at the High Energy Physics Workshop "Scalar Mesons: an
Interesting Puzzle for QCD", Utica, New York, May 200
Radiative vector meson decay
We study the radiative , and decay into and taking into account mechanisms in which there
are two sequential vector-vector-pseudoscalar or
axial-vector--vector--pseudoscalar steps followed by the coupling of a vector
meson to the photon, considering the final state interaction of the two mesons.
Other mechanisms in which two kaons are produced through the same sequential
mechanisms or from vector meson decay into two kaons which undergo final state
interaction leading to the final pair of pions or , are also
considered. The results of the parameter free theory, together with the
theoretical uncertainties, are compared with the latest experimental results at
Frascati and Novosibirsk.Comment: Prepared for the 10th International Symposium on Meson-Nucleon
Physics and the Structure of the Nucleo
Computational Approach to Anaphora Resolution in Spanish Dialogues
This paper presents an algorithm for identifying noun-phrase antecedents of
pronouns and adjectival anaphors in Spanish dialogues. We believe that anaphora
resolution requires numerous sources of information in order to find the
correct antecedent of the anaphor. These sources can be of different kinds,
e.g., linguistic information, discourse/dialogue structure information, or
topic information. For this reason, our algorithm uses various different kinds
of information (hybrid information). The algorithm is based on linguistic
constraints and preferences and uses an anaphoric accessibility space within
which the algorithm finds the noun phrase. We present some experiments related
to this algorithm and this space using a corpus of 204 dialogues. The algorithm
is implemented in Prolog. According to this study, 95.9% of antecedents were
located in the proposed space, a precision of 81.3% was obtained for pronominal
anaphora resolution, and 81.5% for adjectival anaphora
Isospin dependence of the three-nucleon force
We classify --nucleon forces according to their isospin dependence and
discuss the most general isospin structure of the three--nucleon force. We
derive the leading and subleading isospin--breaking corrections to the
three--nucleon force using the framework of chiral effective field theory.Comment: 21 pages, 6 figure
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