Theories in More than Four Dimensions

Particle physics models where there are large hidden extra dimensions are currently on the focus of an intense activity. The main reason is that these large extra dimensions may come with a TeV scale for quantum gravity (or string theory) which leads to a plethora of new observable phenomena in colliders as well in other areas of particle physics. Those new dimensions could be as large as millimeters implying deviations of the Newton's law of gravity at these scales. Intending to provide a basic introduction to this fast developing area, we present a general overview of theories with large extra dimensions. We center our discussion on models for neutrino masses, high dimensional extensions of the Standard Model and gauge coupling unification. We discuss the recently proposed technic of splitting fermion wave functions on a tick brane which may solve the problem of a fast proton decay and produce fermion mass hierarchies without invoking extra global symmetries. Randall-Sundrum model and some current trends are also commented.Comment: LaTeX file, 31 pages, no figures. Minor changes, References added. Lectures given at the IX Mexican School on Particles and Fields, Metepec, Puebla, Mexico, August, 2000. To appear in the proceeding

Peeping into the SU(2) Gauge Vacuum

We study thermalised configurations of SU(2) gauge fields by cooling. An analysis of the effect of cooling is presented and global and statistical information is extracted.Comment: 3 pages, uuencoded compressed postscript file, contribution to LAT 9

Some Ideas and Examples to Evaluate Ontologies

The lack of methods for evaluating ontologies in laboratories can be an obstacle to their use in companies. This paper presents a set of emerging ideas in evaluation of ontologies useful for: (1) ontologies developers in the lab, as a foundation from which to perform technical evaluations; (2) end users of ontologies in companies, as a point of departure in the search for the best ontology for their systems; and (3) future research, as a basis upon which to perform progressive and disciplined investigations in this area. After briefly exploring some general questions such as: why, what, when, how and where to evaluate; who evaluates; and, what to evaluate against, we focus on the definition of a set of criteria useful in the evaluation process. Finally, we use some of these criteria in the evaluation of the Bibliographic-Data [5] ontology