1,971 research outputs found
Probing the EOS of dense neutron-rich matter with high-energy radioactive beams
Nuclear reactions induced by high energy radioactive beams create a transient
state of nuclear matter with high density and appreciable neutron to proton
asymmetry. This will provide a unique opportunity to explore novel properties
of dense neutron-rich matter and the isospin-dependence of the nuclear equation
of state (EOS). Here we study the ratio as a probe of the EOS of
dense neutron-rich matter.Comment: Talk given at NN2003 to appear in the Proc. in Nucl. Phys. A (2004
Kaon condensation in neutron stars and high density behaviour of nuclear symmetry energy
We study the influence of a high density behaviour of the nuclear symmetry
energy on a kaon condensation in neutron stars. We find that the symmetry
energy typical for several realistic nuclear potentials, which decreases at
high densities, inhibits kaon condensation for weaker kaon-nucleon couplings.
There exists a threshold coupling above which the kaon condensate forms at
densities exceeding some critical value. This is in contrast to the case of
rising symmetry energy, as e.g. for relativistic mean field models, when the
kaon condensate can form for any coupling at a sufficiently high density.
Properties of the condensate are also different in both cases.Comment: 12 pages, 7 figures, Acta Phys. Pol. B in pres
Cosmological solutions of emergent noncommutative gravity
Matrix models of Yang-Mills type lead to an emergent gravity theory, which
may not require fine-tuning of a cosmological constant. We find cosmological
solutions of Friedmann-Robertson-Walker type. They generically have a big
bounce, and an early inflation-like phase with graceful exit. The mechanism is
purely geometrical, no ad-hoc scalar fields are introduced. The solutions are
stabilized through vacuum fluctuations and are thus compatible with quantum
mechanics. This leads to a Milne-like universe after inflation, which appears
to be in remarkably good agreement with observation and may provide an
alternative to standard cosmology.Comment: 4 pages, 2 figures. V2: version accepted by Phys.Rev.Lett. plus one
pictur
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