723 research outputs found
Hypermatter in chiral field theory
We investigate the properties of hadronic matter and nuclei be means of a
generalized model with broken scale invariance. In
mean-field approximation, vector and scalar interactions yield a saturating
nuclear equation of state. Finite nuclei can be reasonably described, too. The
condensates and the effective baryon masses at finite baryon density and
temperature are discussed.Comment: uses IOP style, to be published in Journal of Physics, Proceedings of
the International Symposium on Strangeness in Quark Matter 1997, April 14-18,
Thera (Santorini), Hella
An improved multi-agent simulation methodology for modelling and evaluating wireless communication systems resource allocation algorithms
Multi-Agent Systems (MAS) constitute a well known approach in modelling dynamical real world systems. Recently, this technology has been applied to Wireless Communication Systems (WCS), where efficient resource allocation is a primary goal, for modelling the physical entities involved, like Base Stations (BS), service providers and network operators. This paper presents a novel approach in applying MAS methodology to WCS resource allocation by modelling more abstract entities involved in WCS operation, and especially the concurrent network procedures (services). Due to the concurrent nature of a WCS, MAS technology presents a suitable modelling solution. Services such as new call admission, handoff, user movement and call termination are independent to one another and may occur at the same time for many different users in the network. Thus, the required network procedures for supporting the above services act autonomously, interact with the network environment (gather information such as interference conditions), take decisions (e.g. call establishment), etc, and can be modelled as agents. Based on this novel simulation approach, the agent cooperation in terms of negotiation and agreement becomes a critical issue. To this end, two negotiation strategies are presented and evaluated in this research effort and among them the distributed negotiation and communication scheme between network agents is presented to be highly efficient in terms of network performance. The multi-agent concept adapted to the concurrent nature of large scale WCS is, also, discussed in this paper
Chiral model for dense, hot and strange hadronic matter
An extended chiral SU(3) model is applied to the description of dense, hot
and strange hadronic matter. The degrees of freedom are the baryon octet and
decuplet and the spin-0 and spin-1 meson multiplets. The parameters of the
model are fitted to the hadron masses in vacumm, infinite nuclear matter
properties and soft pion theorems. At high densities the appearance of density
isomers cannot be ruled out and extrapolation to finite temperature exhibits a
first order phase transition at . The predicted dropping
baryon masses lead to drastically changed particle ratios compared to ideal gas
calculations.Comment: 4 pages, 3 figures, Contribution to the Proceedings of the 15th
Particles and Nuclei International Conference (PANIC 99), Uppsala, Sweden,
June 10-16, 199
Hadrons in Dense Resonance-Matter: A Chiral SU(3) Approach
A nonlinear chiral SU(3) approach including the spin 3/2 decuplet is
developed to describe dense matter. The coupling constants of the baryon
resonances to the scalar mesons are determined from the decuplet vacuum masses
and SU(3) symmetry relations. Different methods of mass generation show
significant differences in the properties of the spin-3/2 particles and in the
nuclear equation of state.Comment: 28 pages, 9 figure
Twisted polarization domains and their dynamics
We provide a theoretical investigation of optical Poincar\'e beams that
exhibit interwinding chiral polarized domains upon propagation. We employ both
analytical and numerical methods in order to investigate this phenomenon.
Specifically, we introduce the theoretical framework that elucidates the
formation and spiraling behavior of chiral polarized domains of light.
Additionally, we define dynamic quantities that help us understand and quantify
the angular motion of these domains. We apply this method to cylindrically
symmetric optical beams, thereby unveiling their distinct radial and
longitudinal propagation dynamics
Neutron star properties in a chiral SU(3) model
We investigate various properties of neutron star matter within an effective
chiral model. The predictions of this model are
compared with a Walecka-type model. It is demonstrated that the importance of
hyperon degrees are strongly depending on the interaction used, even if the
equation of state near saturation density is nearly the same in both models.
While the Walecka-type model predicts a strange star core with strangeness
fraction , the chiral model allows only for
and predicts that , and will not exist in star, in
contrast to the Walecka-type model.Comment: 13 pages, Revtex, 5 figs include
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