Elementary particle physics has been crowned with spectacular successes in this last quarter of the past century. The cornerstone of such a success is the Standard Model of Elementary Particles which has been tested to a high level of precision. The Standard Model (SM), however, is incomplete. It cannot predict the number of "families". (Experimentally, one knows that there at least three families.) It cannot predict the electroweak mixing angle which is measured to a high level of accuracy. One does not know the origin of the masses of the constituents of matter: the quarks and the leptons. Moreover, the SM cannot accommodate a mass for the neutrinos: a feature which is strongly suggested by recent experiments on neutrino oscillations. To answer some of these questions, there is a need to go beyond the Standard Model (and possibly search for some form of unification). What this Physics Beyond the Standard Model might be has become one of the most active areas of research in Particle Physics.
For the past few years, there has been an intense interest in the possibility that there might exist extra dimensions beyond the known four (three spatial and one time dimensions). This new approach has opened up new visions into old problems in Particle Physics, such as the mass hierarchy of the quarks and leptons for example, as well as to why the neutrinos appear to be so much lighter than their charged lepton partners. This is one of the directions that I have embarked upon. Most recently, I have looked into possibilities that the Standard Model might merge, at an energy scale which is not-too-distant from the mass of the Z boson, into a larger theory dubbed "Petite Unification" in which one can predict the value of the electroweak mixing angle.