Testing 2HDM at Muon Colliders

One very light neutral Higgs scalar with mass, say, below 40-50 GeV is still allowed in the non-supersymmetric 2HDM (Model II), while the remaining particles of the Higgs sector in this model have to be heavier. The possibility of testing such a scenario at Muon Colliders is discussed.Comment: 6 pages, 4 Postscript figures, uses aipproc.sty. Presented at the Workshop on Physics at the First Muon Collider and at the Front End of a Muon Collider, Fermilab, November 199

Communities and classes in symmetric fractals

Two aspects of fractal networks are considered: the community structure and the class structure, where classes of nodes appear as a consequence of a local symmetry of nodes. The analysed systems are the networks constructed for two selected symmetric fractals: the Sierpinski triangle and the Koch curve. Communities are searched for by means of a set of differential equations. Overlapping nodes which belong to two different communities are identified by adding some noise to the initial connectivity matrix. Then, a node can be characterized by a spectrum of probabilities of belonging to different communities. Our main goal is that the overlapping nodes with the same spectra belong to the same class

Combinatorial aspect of fashion

Simulations are performed according to the Axelrod model of culture dissemination, with modified mechanism of repulsion. Previously, repulsion was considered by Radillo-Diaz et al (Phys. Rev. E 80 (2009) 066107) as dependent on a predefined threshold. Here the probabilities of attraction and repulsion are calculated from the number of cells in the same states. We also investigate the influence of some homogeneity, introduced to the initial state. As the result of the probabilistic definition of repulsion, the ordered state vanishes. A small cluster of a few percent of population is retained only if in the initial state a set of agents is prepared in the same state. We conclude that the modelled imitation is successful only with respect to agents, and not only their features

Heavy quark photoproduction at THERA

Measurements of heavy quark production at a possible future $ep$ facility, THERA, would provide valuable information on the structure of the photon. QCD cross-section predictions are made at LO for both charm and beauty production and their sensitivity to current parametrisations of the photon parton densities is investigated.Comment: 10 pages, 9 figures. To appear in "The THERA Book", DESY-LC-REV-2001-062. IFT 2001/