64,165 research outputs found
Meson decay in the Fock-Tani Formalism
The Fock-Tani formalism is a first principle method to obtain effective
interactions from microscopic Hamiltonians. Usually this formalism was applied
to scattering, here we introduced it to calculate partial decay widths for
mesons.Comment: Presented at HADRON05 XI. "International Conference on Hadron
Spectroscopy" Rio de Janeiro, Brazil, August 21 to 26, 200
Meson decay in a corrected model
Extensively applied to both light and heavy meson decay and standing as one
of the most successful strong decay models is the model, in which
pair production is the dominant mechanism. The pair production can
be obtained from the non-relativistic limit of a microscopic interaction
Hamiltonian involving Dirac quark fields. The evaluation of the decay amplitude
can be performed by a diagrammatic technique for drawing quark lines. In this
paper we use an alternative approach which consists in a mapping technique, the
Fock-Tani formalism, in order to obtain an effective Hamiltonian starting from
same microscopic interaction. An additional effect is manifest in this
formalism associated to the extended nature of mesons: bound-state corrections.
A corrected is obtained and applied, as an example, to
and decays.Comment: 3 figures. To appear in Physical Review
A spatial scan statistic for zero-inflated Poisson process
The scan statistic is widely used in spatial cluster detection applications
of inhomogeneous Poisson processes. However, real data may present substantial
departure from the underlying Poisson process. One of the possible departures
has to do with zero excess. Some studies point out that when applied to data
with excess zeros, the spatial scan statistic may produce biased inferences. In
this work, we develop a closed-form scan statistic for cluster detection of
spatial zero-inflated count data. We apply our methodology to simulated and
real data. Our simulations revealed that the Scan-Poisson statistic steadily
deteriorates as the number of zeros increases, producing biased inferences. On
the other hand, our proposed Scan-ZIP and Scan-ZIP+EM statistics are, most of
the time, either superior or comparable to the Scan-Poisson statistic
Opening the Pandora's box of quantum spinor fields
Lounesto's classification of spinors is a comprehensive and exhaustive
algorithm that, based on the bilinears covariants, discloses the possibility of
a large variety of spinors, comprising regular and singular spinors and their
unexpected applications in physics and including the cases of Dirac, Weyl, and
Majorana as very particular spinor fields. In this paper we pose the problem of
an analogous classification in the framework of second quantization. We first
discuss in general the nature of the problem. Then we start the analysis of two
basic bilinear covariants, the scalar and pseudoscalar, in the second quantized
setup, with expressions applicable to the quantum field theory extended to all
types of spinors. One can see that an ampler set of possibilities opens up with
respect to the classical case. A quantum reconstruction algorithm is also
proposed. The Feynman propagator is extended for spinors in all classes.Comment: 18 page
- …