40 research outputs found
Charmed mesons in nuclear matter
We obtain the properties of charmed mesons in dense matter using a
coupled-channel approach which accounts for Pauli blocking effects and meson
self-energies in a self-consistent manner. We study the behaviour of
dynamically-generated baryonic resonances together with the open-charm meson
spectral functions in this dense nuclear environment. We discuss the
implications of the in-medium properties of open-charm mesons on the
and the predicted X(3700) scalar resonances, and on the
formation of -mesic nuclei.Comment: 5 pages, 5 figures, 1 table, to appear in Proceedings of XIII
International Conference on Hadron Spectroscopy, November 29 - December 4,
2009, Florida State Universit
Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances
We study the interaction of vector mesons with the octet of stable baryons in
the framework of the local hidden gauge formalism using a coupled channels
unitary approach, including also the pseudoscalar-baryon channels which couple
to the same quantum numbers. We examine the scattering amplitudes and their
poles, which can be associated to known baryon resonances,
and determine the role of the pseudoscalar-baryon channels, changing the width
and eventually the mass of the resonances generated with only the basis of
vector-baryon states
Baryon Resonances
In this talk I show recent results on how many excited baryon resonances
appear as systems of one meson and one baryon, or two mesons and one baryon,
with the mesons being either pseudoscalar or vectors. Connection with
experiment is made including a discussion on old predictions and recent results
for the photoproduction of the resonance, as well as the
prediction of one baryon state around 1920 MeV which might have been
seen in the reaction.Comment: Talk given at the 10th International Conference on Hypernuclear and
Strange Particle Physics, Tokai, Japan, Sptember 200
The coupling in the chiral unitary approach and the isoscalar , interaction
We evaluate the "" exchange contribution to the
scattering within a chiral unitary approach. We show that the chiral transition
potentials for in the -channel lead to a ""
contribution that vanishes in the forward direction and, hence, would
produce a null "" exchange contribution to the optical potential
in nuclear matter in a simple impulse approximation. This is a consequence of
the fact that the leading order chiral Lagrangian gives an I=0 amplitude proportional to the squared momentum transfer, . This
finding poses questions on the meaning or the origin of "" exchange
potentials used in relativistic mean field approaches to the nuclear
selfenergy. This elementary "" exchange potential in
is compared to the Weinberg-Tomozawa term and is found to
be smaller than present theoretical uncertainties but will be relevant in the
future when aiming at fitting increasingly more accurate data.Comment: new channels and higher order contributions included. Published
versio
Penta-quark states with hidden charm and beauty
More and more hadron states are found to be difficult to be accommodated by
the quenched quark models which describe baryons as 3-quark states and mesons
as antiquark-quark states. Dragging out an antiquark-quark pair from the gluon
field in hadrons should be an important excitation mechanism for hadron
spectroscopy. Our recent progress on the penta-quark states with hidden charm
and beauty is reviewed.Comment: Plenary talk at the 5th Asia-Pacific Conference on Few-Body Problems
in Physics 2011 (APFB2011), 22-26 Aug., 2011, Seoul, Kore