10,232 research outputs found
Baryonic Resonances from the Interactions of the Baryon Decuplet and Meson Octet
We study -wave interactions of the baryon decuplet with the octet of
pseudoscalar mesons using the lowest order chiral Lagrangian. We find two bound
states in the SU(3) limit corresponding to the octet and decuplet
representations. These are found to split into eight different trajectories in
the complex plane when the SU(3) symmetry is broken gradually. Finally, we are
able to provide a reasonable description for a good number of 4-star
resonances listed by the Particle Data Group. In particular, the
, the and the states are well
reproduced. We predict a few other resonances and also evaluate the couplings
of the observed resonances to the various channels from the residues at the
poles of the scattering matrix from where partial decay widths into different
channels can be evaluated.Comment: Contribution to the HADRON05 Conference, Rio de Janeiro, September
200
Meson Exchange Currents in Kaon Scattering on the Lightest Nuclei
The K^+ scattering on the lightest nuclei, d, 3He and 4He is studied in the
framework of multiple scattering theory. Effects from MEC tied to the
K^+N-->KNpi reaction are evaluated. We found that at momentum transfers Q^2<0.5
(GeV/c)^2 contributions from MEC are much smaller than kaon rescattering
corrections. This makes the conventional multiple scattering picture a reliable
tool to study these reactions in this kinematical domain and to extract the
K^+n scattering amplitude from the K^+d data. At larger transferred momentum
MEC can become more relevant.Comment: revtex, 16 pages, 6 figure
Properties of the ground-state baryons in chiral perturbation theory
We review recent progress in the understanding of low-energy baryon structure
by means of chiral perturbation theory. In particular, we discuss the
application of this formalism to the description of various properties such as
the baryon-octet magnetic moments, the electromagnetic structure of decuplet
resonances and the hyperon vector coupling . Moreover, we present the
results on the chiral extrapolation of recent lattice QCD results on the
lowest-lying baryon masses and we predict the corresponding baryonic
sigma-terms.Comment: 6 pages; shortened version to appear in the proceedings of QCD1
Formation of mesic nuclei
We study the structure and formation of the mesic nuclei to
investigate the in-medium modification of the -meson spectral function at
finite density. We consider (), () and ()
reactions to produce a -meson inside the nucleus and evaluate the effects
of its medium modifications to the reaction cross sections. We also estimate
the consequences of the uncertainties of the selfenergy in medium to
the -nucleus interaction. We find that it may be possible to see a peak
structure in the reaction spectra for the strong attractive potential cases. On
the other hand, for strong absorptive interaction cases with relatively weak
attractions, it is very difficult to observe clear peaks and we may need to
know the spectrum shape in a wide energy region to deduce the properties of
.Comment: 11 pages, 8 figure
The lowest-lying baryon masses in covariant SU(3)-flavor chiral perturbation theory
We present an analysis of the baryon-octet and -decuplet masses using
covariant SU(3)-flavor chiral perturbation theory up to next-to-leading order.
Besides the description of the physical masses we address the problem of the
lattice QCD extrapolation. Using the PACS-CS collaboration data we show that a
good description of the lattice points can be achieved at next-to-leading order
with the covariant loop amplitudes and phenomenologically determined values for
the meson-baryon couplings. Moreover, the extrapolation to the physical point
up to this order is found to be better than the linear one given at
leading-order by the Gell-Mann-Okubo approach. The importance that a reliable
combination of lattice QCD and chiral perturbation theory may have for hadron
phenomenology is emphasized with the prediction of the pion-baryon and
strange-baryon sigma terms.Comment: Typos in formulas correcte
Charged current neutrino induced coherent pion production
We analyze the neutrino induced charged current coherent pion production at
the energies of interest for recent experiments like K2K and MiniBooNE. Medium
effects in the production mechanism and the distortion of the pion wave
function, obtained solving the Klein Gordon equation with a microscopic optical
potential, are included in the calculation. We find a strong reduction of the
cross section due to these effects and also substantial modifications of the
energy distributions of the final lepton and pion.Comment: 11 pages, 6 figures. Some details and new references added; results
unchanged. Accepted in PR
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