12,302 research outputs found
Effective kaon energy from a novel chiral SU(3) model
A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and anti-kaons in the nuclear medium. The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-BrĂŒckner theory. After introducing the coupling between the omega meson and the kaon, our results for e ective kaon and anti-kaon energy are quite similar as calculated in the one-boson-exchange model
Nuclear Symmetry Energy with Strangeness in Heavy Ion Collision
The role of anti-kaons in the symmetry energy to be determined in heavy-ion
collisions as for instance in such observables as the ratio is
discussed using a simple chiral Lagrangian. It is shown, with some mild
assumptions, that kaons, when present in the system, can affect the EoS
appreciably for both symmetric and asymmetric nuclear matter. For nuclear
matter with small asymmetry with which heavy-ion collisions are studied, it may
be difficult to distinguish a stiff symmetry energy and the supersoft symmetry
energy, even with kaons present. However the effect of kaon is found to be
significant such that near , at which the chemical
potential difference is zero without kaon amplitude. We present the argument
that in order to obtain a reliably accurate equation of state (EoS) for
compact-star matter, a much deeper understanding is needed on how the
strangeness degrees of freedom such as kaons, hyperons etc. behave in baryonic
matter in a Fermi liquid (or possibly a non-Fermi liquid) phase with potential
phase changes. It is suggested that such an {\em accurate} treatment could have
an important implication on possibly modified gravity.Comment: 13 pages, 3 figures. revised for publicatio
Kaon effective mass and energy from a novel chiral SU(3) symmetric Lagrangian
A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and antikaons in the nuclear medium, the ground state of dense matter and the kaon-nuclear interactions consistently. The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-BrĂŒckner theory. After taking into account the coupling between the omega meson and the kaon, we obtain similar results for the e ective kaon and antikaon energies as calculated in the one-boson-exchange model while in our model the parameters of the kaon-nuclear interactions are constrained by the SU(3) chiral symmetry. PACS number(s): 14.40.Aq, 12.39.Fe, 21.30.F
Half-Skyrmions, Tensor Forces and Symmetry Energy in Cold Dense Matter
In a previous article, the 4D half-skyrmion (or 5D dyonic salt) structure of
dense baryonic matter described in crystalline configuration in the large
limit was shown to impact nontrivially on how anti-kaons behave in compressed
nuclear matter with a possible implication on an "ice-9" phenomenon of deeply
bound kaonic matter and condensed kaons in compact stars. We extend the
analysis to make a further prediction on the scaling properties of hadrons that
have a surprising effect on the nuclear tensor forces, the symmetry energy and
hence on the phase structure at high density. We treat this problem relying on
certain topological structure of chiral solitons. Combined with what can be
deduced from hidden local symmetry for hadrons in dense medium and the "soft"
dilatonic degree of freedom associated with the trace anomaly of QCD, we
uncover a novel structure of chiral symmetry in the "supersoft" symmetry energy
that can influence the structure of neutron stars.Comment: 8 pages, 4 figures; contents unchanged but expanded for a journa
Kaons and antikaons in asymmetric nuclear matter
The properties of kaons and antikaons and their modification in isospin
asymmetric nuclear matter are investigated using a chiral SU(3) model. These
isospin dependent medium effects are important for asymmetric heavy ion
collision experiments. In the present work, the medium modifications of the
energies of the kaons and antikaons, within the asymmetric nuclear matter,
arise due to the interactions of kaons and antikaons with the nucleons and
scalar mesons. The values of the parameters in the model are obtained by
fitting the saturation properties of nuclear matter and kaon-nucleon scattering
lengths. The pion-nucleon scattering lengths are also calculated within the
chiral effective model and compared with earlier results from the literature.
The density dependence of the isospin asymmetry is seen to be appreciable for
the kaon and antikaon optical potentials. This can be particularly relevant for
the future accelerator facility FAIR at GSI, where experiments using neutron
rich beams are planned to be used in the study of compressed baryonic matter
Strange mesons in dense nuclear matter
Experimental data on the production of kaons and antikaons in heavy ion
collisions at relativistic energies are reviewed with respect to in-medium
effects. The ratios measured in nucleus-nucleus collisions are 1 - 2
orders of magnitude larger than in proton-proton collisions. The azimuthal
angle distributions of mesons indicate a repulsive kaon-nucleon
potential. Microscopic transport calculations consistently explain both the
yields and the emission patterns of kaons and antikaons when assuming that
their properties are modified in dense nuclear matter. The production
excitation functions measured in light and heavy collision systems provide
evidence for a soft nuclear equation-of-state.Comment: 16 pages, 12 figures, Invited talk at the 7. international Conference
Nucleus-Nucleus Collisions, Strasbourg, July 3-7, 200
Strangeness at SIS energies
In this contribution we discuss the physics of strange hadrons in low energy
() heavy ion collision. In this energy range the relevant
strange particle are the kaons and anti-kaons. The most interesting aspect
concerning these particles are so called in-medium modifications. We will
attempt to review the current status of understanding of these in medium
modifications. In addition we will briefly discuss other issues related with
kaon production, such as the nuclear equation of state and chemical
equilibrium.Comment: Proceedings Strange Quark Matter 2003, Atlantic Beach, NC, USA, March
200
Moments of meson spectral functions in vacuum and nuclear matter
Moments of the meson spectral function in vacuum and in nuclear matter
are analyzed, combining a model based on chiral SU(3) effective field theory
(with kaonic degrees of freedom) and finite-energy QCD sum rules. For the
vacuum we show that the spectral density is strongly constrained by a recent
accurate measurement of the cross section. In nuclear
matter the spectrum is modified by interactions of the decay kaons with
the surrounding nuclear medium, leading to a significant broadening and an
asymmetric deformation of the meson peak. We demonstrate that both in
vacuum and nuclear matter, the first two moments of the spectral function are
compatible with finite-energy QCD sum rules. A brief discussion of the
next-higher spectral moment involving strange four-quark condensates is also
presented.Comment: 7 pages, 5 figures; published versio
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