Article

# Subthreshold kaon production and the nuclear equation of state

Cyclotron Institute and Physics Department, Texas A&M University, College Station, TX 77843, USA
Physics Letters B (Impact Factor: 6.02). 11/1994; DOI: 10.1016/0370-2693(95)00301-Z
Source: arXiv

ABSTRACT We reexamine in the relativistic transport model the dependence of kaon yield on the nuclear equation of state in heavy ion collisions at energies that are below the threshold for kaon production from the nucleon-nucleon interaction in free space. For Au+Au collisions at GeV/nucleon, we find that the kaon yield measured by the Kaos collaboration at GSI can be accounted for if a soft nuclear equation of state is used. We also confirm the results obtained in non-relativistic transport models that the dependence of kaon yield on the nuclear equation of state is more appreciable in heavy ion collisions at lower incident energies. We further clarify the difference between the predictions from the relativistic transport model and the non-relativistic transport model with a momentum-dependent potential.

0 Bookmarks
·
126 Views
• Source
##### Article: On pp → pKΛ, NKΣ, ppϕ — the Basic Ingredients for Strangeness Production in Heavy Ion Collisions
[Hide abstract]
ABSTRACT: The strangeness production in heavy ion collisions was proposed to be probes of the nuclear equation of state, Kaon potential in nuclear medium, strange quark matter and quark-gluon plasma, etc. However, to act as reliable probes, proper understanding of the basic ingredients for the strangeness production, such as pp → pK+Λ, pp → ppϕ and pp → nK+Σ+ is necessary. Recent study of these reactions clearly shows that previously ignored contributions from the spin-parity 1/2- resonances, N*(1535) and Δ*(1620), are in fact very important for these reactions, especially for near-threshold energies. It is necessary to include these contributions for getting reliable calculation for the strangeness production in heavy ion collisions.
International Journal of Modern Physics E 10/2008; 17(09):1753-1764. · 0.84 Impact Factor
• Source
##### Article: Dynamics of strangeness and collective flows in heavy-ion collisions near threshold energies
[Hide abstract]
ABSTRACT: Strangeness (K\$^{0,+}\$, \$\Lambda\$ and \$\Sigma^{-,0,+}\$) production in heavy-ion collisions near threshold energies has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model. The kaon (anti-kaon)-nucleon and hyperon-nucleon potentials in dense nuclear matter are implemented in the model, which are computed from the chiral perturbation approach and the relativistic mean-field model, respectively. It is found that the in-medium potentials change the structure of transverse flow, and also affect the rapidity distributions and the inclusive spectra for strangeness production. The local temperature of the fire ball extracted from the kaon spectra of inclusive invariant cross sections is influenced by the kaon-nucleon potential. The stiffness of nuclear symmetry energy and the kaon-nucleon potential by distinguishing isospin effect play a significant role on the ratio of K\$^{0}\$/K\$^{+}\$, in particular at the subthreshold energies. The ratio of \$\Sigma^{-}/\Sigma^{+}\$ depends on the high-density symmetry energy, in which the \$\Sigma\$-nucleon potential has a neglectable contribution on the isospin ratio.
Nuclear Physics A 10/2013; 919. · 2.50 Impact Factor
• Source
##### Article: pp-->pK+Λ reaction in an effective Lagrangian model
[Hide abstract]
ABSTRACT: We investigate the pp-->pK+Λ reaction within an effective Lagrangian model where the contributions to the amplitudes are taken into account within the tree level. The initial interaction between the two nucleons is modeled by the exchange of π, ρ, ω, and σ mesons, and the ΛK+ production proceeds via the excitation of the N*(1650), N*(1710), and N*(1720) baryonic resonances. The parameters of the model at the nucleon-nucleon-meson vertices are determined by fitting the elastic nucleon-nucleon scattering with an effective interaction based on the exchange of these four mesons, while those at the resonance vertices are calculated from the known decay widths of the resonances as well as the vector meson dominance model. Available experimental data is described well by this approach. The one-pion-exchange diagram dominates the production process at both higher and lower beam energies. The ρ and ω meson exchanges make negligible contributions. However, the σ-exchange processes contribute substantially to the total cross sections at lower beam energies. The excitation of the N*(1710) and N*(1650) resonances dominate this reaction at beam momenta above and below 3 GeV/c, respectively. The interference among the amplitudes of various resonance excitation processes is significant. For beam energies very close to the K+ production threshold the hyperon-proton final state interaction effects are quite important. The data is selective about the model used to describe the low-energy scattering of the two final state baryons.
Physical Review C 11/1999; 60(5):55213-. · 3.88 Impact Factor