7,796 research outputs found
Kaon dispersion relation and flow in relativistic heavy-ion collisions
Within the framework of a relativistic transport model (ART) for heavy-ion
collisions at AGS energies, we examine the effects of kaon dispersion relation
on the transverse flow of kaons and their transverse momentum and azimuthal
angle distributions. We find that the transverse flow is the most sensitive
observable for studying the kaon dispersion relation in dense medium.Comment: 7 pages, latex, 3 figures available upon request from the authors,
Phys. Rev. C (1996) in pres
Pion flow and antiflow in relativistic heavy-ion collisions
Within the framework of a relativistic transport model (ART) for heavy-ion
collisions at AGS energies, we study the transverse flow of pions with respect
to that of nucleons using two complementary approaches. It is found that in
central collisions pions develop a weak flow as a result of the flow of baryon
resonances from which they are produced. On the other hand, they have a weak
antiflow in peripheral collisions due to the shadowing of spectators.
Furthermore, it is shown that both pion flow and antiflow are dominated by
those with large transverse momenta.Comment: Phys. Rev. C, Rapid communication, in press. Figures are available
from the authors upon reques
Medium effects on charged pion ratio in heavy ion collisions
We have recently studied in the delta-resonance--nucleon-hole model the
dependence of the pion spectral function in hot dense asymmetric nuclear matter
on the charge of the pion due to the pion p-wave interaction in nuclear medium.
In a thermal model, this isospin-dependent effect enhances the ratio of
negatively charged to positively charged pions in neutron-rich nuclear matter,
and the effect is comparable to that due to the uncertainties in the
theoretically predicted stiffness of nuclear symmetry energy at high densities.
This effect is, however, reversed if we also take into account the s-wave
interaction of the pion in nuclear medium as given by chiral perturbation
theory, resulting instead in a slightly reduced ratio of negatively charged to
positively charged pions. Relevance of our results to the determination of the
nuclear symmetry energy from the ratio of negatively to positively charged
pions produced in heavy ion collisions is discussed.Comment: 11 pages, 4 figures, contribution to The International Workshop on
Nuclear Dynamics in Heavy-Ion Reactions and the Symmetry Energy (IWND2009),
Shanghai, China, 22-25 August, 200
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