19,429 research outputs found
Critical view of the claimed pentaquark
We use a theoretical model of the reaction
adapted to the experiment done at LEPS where a peak was observed and associated
to the pentaquark. The study shows that the method used in
the experiment to associate momenta to the undetected proton and neutron,
together with the chosen cuts, necessarily creates an artificial broad peak in
the assumed invariant mass in the region of the claimed
. It is shown that the LEPS fit to the data, used to make the
claim of the , grossly distorts the background. An
alternative fit, assuming a background plus a fluctuation, returns a background
practically equal to the theoretical one and a fluctuation identical to the one
seen in the experimental spectrum of 2 significance.Comment: Conference Proceedin
Three body resonances in two meson-one baryon systems
We report four 's and three 's, in the 1500 - 1800 MeV
region, as two meson - one baryon S-wave resonances. We solve Faddeev
equations in the coupled channel approach. The invariant mass of one of the
meson-baryon pairs and that of the three particles have been varied and peaks
in the squared three body -matrix have been found very close to the existing
= -1, low lying baryon resonances. The input two-body
-matrices for meson-meson and meson-baryon interaction have been calculated
by solving the Bethe-Salpeter equation with the potentials obtained in the
chiral unitary approach.Comment: corrected version, new channels evaluated, new references adde
An analysis of the Lattice QCD spectra for and
In this talk I present the results obtained using effective field theories in
a finite volume from a reanalysis of lattice data on the systems,
where bound states of and are found and associated with the states
and , respectively. We confirm the presence of
such states on the lattice data and determine the weight of the channel in
the wave function of and that of in the wave function
of . Our results indicate a large meson-meson component in both
cases.Comment: Conference Proceedings, Hadron 2017, Salamanca, Spai
Infinite horizon economies with borrowing constraints
We consider infinite horizon economies with incomplete financial markets. Securities are in positive net supply and may be infinite-lived. We establish existence of equilibria by requiring borrowing constrains instead of portfolio restrictions..Equilibrium, Infinite horizon incomplete markets, Infinite-lived real assets.
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