102 research outputs found
Pion-Lambda-Sigma Coupling Extracted from Hyperonic Atoms
The latest measurements of the atomic level width in Sigma-hyperonic Pb atom
offer the most accurate datum in the region of low-energy Sigma-hyperon
physics. Atomic widths are due to the conversion of Sigma-nucleon into
Lambda-nucleon. In high angular momentum states this conversion is dominated by
the one-pion exchange. A joint analysis of the data of the scattering of
negative-Sigma on proton converting into a Lambda and a neutron and of the
atomic widths allows to extract a pseudovector pion-hyperon-Sigma coupling
constant of 0.048 with a statistical error of +-0.005 and a systematic one of
+-0.004. This corresponds to a pseudoscalar coupling constant of 13.3 with a
statistical uncertainty of 1.4 and a systematic one of 1.1.Comment: 12 pages, 1 figure, Use of Revtex.st
Search for Deeply Bound Kaonic Nuclear States with AMADEUS
We briefly report on the search for Deeply Bound Kaonic Nuclear States with
AMADEUS in the Sigma0 p channel following K- absorption on 12C and outline
future perspectives for this work
Eta-mesic nuclei in relativistic mean-field theory
With the eta-nucleon (eta N) interaction Lagrangian deduced from chiral
perturbation theory, we study the possible eta-mesic nuclei in the framework of
relativistic mean-field theory. The eta single-particle energies are sensitive
to the eta N scattering length, and increase monotonically with the nucleon
number A. If the scattering length is in the range of a^{eta N}=0.75-1.05 fm
and the imaginary potential V_{0}-15 MeV, some discrete states of C, O and Ne
eta bound states should be identified in experiments. However, when the
scattering length a^{eta N} 30 MeV,
no discrete eta meson bound states could be observed in experiments.Comment: 6 page
Are there eta-Helium bound states?
Using multiple scattering theory the scattering lengths of mesons on
helium nuclei are calculated and checked against final state
interactions from the He and He
reactions. The existence of an He quasibound state is indicated.Comment: revtex, 23 pages, 3 figures available by fax or mai
THE INTERPLAY OF THE K+K- ATOM AND THE f_0(975) RESONANCE
We predict that production of the K+K- atom in pd-3^HeX and similar reactions
exhibits a drastic missing mass spectrum due to the interplay with f_0(975)
resonance. We point out that high precision studies of the K+K- atom may shed a
new light on the nature of f_0(975).Comment: 13 page
Eta-Helium Quasi-Bound States
The cross section and tensor analysing power t_20 of the d\vec{d}->eta 4He
reaction have been measured at six c.m. momenta, 10 < p(eta) < 90 MeV/c. The
threshold value of t_20 is consistent with 1/\sqrt{2}, which follows from
parity conservation and Bose symmetry. The much slower momentum variation
observed for the reaction amplitude, as compared to that for the analogous
pd->eta 3He case, suggests strongly the existence of a quasi-bound state in the
eta-4He system and optical model fits indicate that this probably also the case
for eta-3He.Comment: LaTeX, uses elsart.sty, 10 pages, 3 Postscript figures, Submitted to
Physics Letters
The -3N problem with separable interactions
The -3N-interaction is studied within the four-body Faddeev-Yakubovsky
theory adopting purely separable forms for the two- and three-body
subamplitudes, limiting the basic two-body interactions to s-waves only. The
corresponding separable approximation for the integral kernels is obtained by
using the Hilbert-Schmidt procedure. Results are presented for the -H
scattering amplitude and for the total elastic cross section for energies below
the triton break-up threshold.Comment: revised version accepted for Phys. Rev. C, 16 pages revtex including
6 eps-figures, formal part shortene
The energies and residues of the nucleon resonances N(1535) and N(1650)
We extract pole positions for the N(1535) and N(1650) resonances using two
different models. The positions are determined from fits to different subsets
of the existing , and data
and found to be 1515(10)--i85(15)MeV and 1660(10)--i65(10)MeV, when the data is
described in terms of two poles. Sensitivity to the choice of fitted data is
explored. The corresponding and residues of these poles
are also extracted.Comment: 9 page
The importance of the nucleon-nucleon correlations for the eta alpha S-wave scattering length, and the pi-eta mixing angle in the low-energy eta alpha scattering length model
Using the new set of dd --> eta alpha near threshold experimental data, the
estimate of the importance of the nucleon-nucleon correlations for the eta
alpha S-wave scattering length in the multiple scattering theory is obtained
using the low-energy scattering length model. The contribution turns out to be
much bigger then previously believed. The pi-eta mixing angle is extracted
using the experimental data on the dd --> eta alpha and dd --> pi alpha
processes. The model is dominated by the subthreshold extrapolation recipe for
the eta alpha scattering amplitudes. When the recipe is chosen the model is
completely insensitive to the eta alpha parameters for the subthreshold value
of the eta cm momentum of p_{eta}^2 = -(0.46)^2 fm^{-2}. Provided that the
subthreshold extrapolation recipe is correct, a good estimate of the pi-eta
mixing angle is obtained, if the experimental cross sections for the dd --> pi
alpha reaction at the corresponding deuteron input energy are taken from the
literature.Comment: 8 pages, 2 figure
Search for deeply bound kaonic nuclear states in the AMADEUS experiment
We briefly report on the search for Deeply Bound Kaonic Nuclear States with AMADEUS in the ÎŁ0p channel, and future perspectives
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