707 research outputs found
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
Can the nuclear symmetry potential at supra-saturation densities be negative?
In the framework of an Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU)
transport model, for the central Au+Au reaction at an incident
beam energy of 400 MeV/nucleon, effect of nuclear symmetry potential at
supra-saturation densities on the pre-equilibrium clusters emission is studied.
It is found that for the positive symmetry potential at supra-saturation
densities the neutron to proton ratio of lighter clusters with mass number
() is larger than that of the weighter clusters with
mass number (), whereas for the negative symmetry potential
at supra-saturation densities the is \emph{smaller} than that
of the . This may be considered as a probe of the negative
symmetry potential at supra-saturation densities.Comment: 5 pages, 3 figures, 1 table, to be publishe
Neutrino emissivity under neutral kaon condensation
Neutrino emissivity from neutron star matter with neutral kaon condensate is
considered. It is shown that a new cooling channel is opened, and what is more,
all previously known channels acquire the greater emissivity reaching the level
of the direct URCA cycle in normal matter.Comment: 7 pages, 1 figure, to be published in Phys.Rev.C, revised version:
the sectioning changed and more discussion adde
MesonNet Workshop on Meson Transition Form Factors
The mini-proceedings of the Workshop on Meson Transition Form Factors held in
Cracow from May 29th to 30th, 2012 introduce the meson transition form factor
project with special emphasis on the interrelations between the various form
factors (on-shell, single off-shell, double off-shell). Short summaries of the
talks presented at the workshop follow.Comment: 69 pages, 14 figures; all talks can be found at
https://sites.google.com/site/mesonnetwork/home/activities/form-factor-workshop-2012;
v2: workshop link updated (as the page had to be moved to a commercial
server), table 6 correcte
omega --> pi0 gamma* and phi --> pi0 gamma* Transition form factors in dispersion theory
We calculate the omega --> pi0 gamma* and phi --> pi0 gamma* electromagnetic
transition form factors based on dispersion theory, relying solely on a
previous dispersive analysis of the corresponding three-pion decays and the
pion vector form factor. We compare our findings to recent measurements of the
omega --> pi0 mu+ mu- decay spectrum by the NA60 collaboration, and strongly
encourage experimental investigation of the Okubo-Zweig-Iizuka-forbidden phi
--> pi0 l+ l- decays in order to understand the strong deviations from
vector-meson dominance found in these transition form factors.Comment: 11 pages, 8 figures; references updated, version published in Phys.
Rev.
Electromagnetic form factors of the baryon octet in the perturbative chiral quark model
We apply the perturbative chiral quark model at one loop to analyze the
electromagnetic form factors of the baryon octet. The analytic expressions for
baryon form factors, which are given in terms of fundamental parameters of
low-energy pion-nucleon physics (weak pion decay constant, axial nucleon
coupling, strong pion-nucleon form factor), and the numerical results for
baryon magnetic moments, charge and magnetic radii are presented. Our results
are in good agreement with experimental data.Comment: 15 pages, 6 figures, to be published in Eur. Phys. J.
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