58 research outputs found
Latest results for the antikaon-nucleon optical potential
The key question of this letter is whether the K-nucleus optical potential is
deep, as it is prefered by the phenomenological fits to kaonic atoms data, or
shallow, as it comes out from unitary chiral model calculations. The current
experimental situation is reviewed.Comment: 3 pages, 1 figure. Presented at the 21st European Conference on the
Few-Body problems in Physics (EFB21), Salamanca, Spain, August 29 - September
3, 201
Recent developments in chiral dynamics of hadrons and hadrons in a nuclear medium
In this talk I present recent developments in chiral dynamics of hadrons and
hadrons in a medium addressing the following points: interaction of the octet
of pseudoscalar mesons with the octet of baryons of the nucleon, showing recent
experimental evidence on the existence of two states, the
interaction of the octet of pseudoscalar mesons with the decuplet of baryons of
the , with particular emphasis on the resonance,
dynamically generated by this interaction. Then I review the interaction of
kaons in a nuclear medium and briefly discuss the situation around the claims
of deeply bound states in nuclei. The large renormalization of the
in the nuclear medium is shown as another example of successful
application of the chiral unitary techniques.Comment: Talk at the Fifth International Conference on Perspectives in
Hadronic Physics: Particle-Nucleus and Nucleus-Nucleus Scattering at
Relativistic Energies, Trieste, May 200
The (K-,p) reaction on nuclei with in-flight kaons
We perform a theoretical study of the spectrum of protons with kinetic
energies of around 600 MeV, emitted following the interaction of 1 GeV/c kaons
with nuclei. A recent experimental analysis of this (K-,p) reaction on 12C,
based on the dominant quasielastic process, has suggested a deeply attractive
kaon nucleus potential. Our Monte Carlo simulation considers, in addition, the
one-and two-nucleon K- absorption processes producing hyperons that decay into
\pi N pairs. We find that this kaon in-flight reaction is not well suited to
determine the kaon optical potential due, essentially, to the limited
sensitivity of the cross section to its strength, but also to unavoidable
uncertainties from the coincidence requirement applied in the experiment. A
shallow kaon nucleus optical potential obtained in chiral models is perfectly
compatible with the observed spectrum.Comment: To appear in the proceedings of the 10th International Conference on
Hypernuclear and Strange Particle Physics, Tokai, Ibaraki (Japan), 14-18
September, 200
Effective String Rope Model for the initial stages of Ultra-Relativistic Heavy Ion Collisions
Different approaches to describe initial stages of relativistic heavy ion
collisions are discussed qualitatively and quantitatively. An Effective String
Rope Model is presented for heavy ion collisions at RHIC energies. Our model
takes into account baryon recoil for both target and projectile, arising from
the acceleration of partons in an effective field, produced in the collision.
The typical field strength (string tension) for RHIC energies is about 5-12
GeV/fm, what allows us to talk about ``string ropes''. The results show that a
QGP forms a tilted disk, such that the direction of the largest pressure
gradient stays in the reaction plane, but deviates from both the beam and the
usual transverse flow directions. The produced initial state can be used as an
initial condition for further hydrodynamical calculations. Such initial
conditions lead to the creation of third flow component.Comment: 47 pages, 14 figures. Minor changes were made, style was changed to
"elsart". Paper is accepted to Nucl. Phys.
Can supercooling explain the HBT puzzle?
Possible hadronization of supercooled QGP, created in heavy ion collisions at
RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a
hadronization is expected to be a very fast shock-like process, what, if
hadronization coincides or shortly followed by freeze out, could explain a part
of the HBT puzzle, i.e. the flash-like particle emission
(). HBT data also show that the expansion time
before freeze out is very short (). In this work we discuss
question of supercooled QGP and the timescale of the reaction.Comment: 9 pages, 2 figure
The meson width in the medium from proton induced production in nuclei
We perform calculations for the production of mesons in nuclei at
energies just above threshold and study the dependence of the cross
section. We use results for the selfenergy in the medium obtained within
a chiral unitary approach. We find a strong dependence which is tied to the
distortion of the incident proton and to the absorption of the in its
way out of the nucleus. The effect of this latter process reduces the cross
section in about a factor two in heavy nuclei proving that the dependence
of the cross section bears valuable information on the width in the
nuclear medium. Calculations are done for energies which are accessible in an
experimental facility like COSY.Comment: 26 pages, 13 figures. More detailed calculations have been performed.
Paper is accepted for publication in Phys. Rev.
Large enhancement from freeze out
Freeze out of particles across three dimensional space-time hypersurface is
discussed in a simple kinetic model. The final momentum distribution of emitted
particles, for freeze out surfaces with space-like normal, shows a
non-exponential transverse momentum spectrum. The slope parameter of the
distribution increases with increasing , in agreement with recently
measured SPS pion and spectra.Comment: 8 pages, 1 figure. Accepted for publication in Physics Letters
Bound states of in nuclei
We study the binding energy and the width of the in nuclei,
associated to the and components. The first one leads to
negligible contributions while the second one leads to a sizeable attraction,
enough to bind the in nuclei. Pauli blocking and binding effects on
the decay reduce considerably the decay width in nuclei and
medium effects associated to the component also lead to a very small
width, as a consequence of which one finds separation between the bound levels
considerably larger than the width of the states.Comment: Presentation in the 10th International Baryon Conference BARYON0
Freeze-out in hydrodynamical models in relativistic heavy ion collisions
Freeze-out of particles across 3-dimensional space-time hypersurface with
space-like normal is discussed in a simple kinetic model. The final momentum
distribution of emitted particles shows a non-exponential transverse momentum
spectrum, which is in quantitative agreement with recently measured SPS pion
and spectra.Comment: 4 pages, 1 figure. Quark Matter'99 Proceeding
Statistical Hadronization of Supercooled Quark-Gluon Plasma
The fast simultaneous hadronization and chemical freeze out of supercooled
quark-gluon plasma, created in relativistic heavy ion collisions, leads to the
re-heating of the expanding matter and to the change in a collective flow
profile. We use the assumption of statistical nature of the hadronization
process, and study quantitatively the freeze out in the framework of
hydrodynamical Bjorken model with different quark-gluon plasma equations of
state.Comment: 7 pages, 3 figure
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