Two Universal Extra Dimensions

We review the main results of the study of the Standard model propagating in two universal extra dimensions. Gauge bosons give rise to heavy spin-1 and spin-0 particles. The latter constitute the lightest Kaluza-Klein (KK) particle in the level (1,0). The level (1,1) can be s-channel produced. The main signals at the Tevatron and the LHC will be several $t\bar t$ resonances.Comment: 4 pages, to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

Theories with Extra Dimensions

We review some aspects of theories with compact extra dimensions. We consider the motivation and the theoretical basis of Large, Universal and Warped Extra Dimensions. We focus on those aspects that are potentially relevant in the phenomenology at colliders.Comment: 10 pages, 9 figures, Presented at The 15th International Conference on Hadron Collider Physics, East Lansing, MI, June 14-18 200

Constraints on Semileptonic Form-factors from Dispersive Sum Rules

I briefly discuss the derivation of dispersive sum rules constraining semileptonic form-factors. I outline the use of these constraints in the context of charmless semileptonic decays and suggest how, in combination with other theoretical and experimental information, they may reduce the uncertainties in the extraction of $V_{ub}$.Comment: 6 pages, 1 ps figure included. Uses sprocl.sty. Talk presented at the 2nd Conference on B Physics and CP Violation, Honolulu, Hawaii, March 24-27 199

New Solutions to the Hierarchy Problem

After summarizing the status of the Standard Model, we focus on the Hierarchy Problem and why we believe this strongly suggests the need for new physics at the TeV scale. We then concentrate on theories with extra dimensions and their possible manifestations at this scale.Comment: Presented at the First Latin American Workshop on High Energy Physics, Porto Alegre, December 3-5 200

Theoretical Issues in Rare K, D and B Decays

I discuss some theoretical aspects of rare $K$, $D$ and $B$ decays focusing mainly on their potential as tests of the one loop structure of the standard model. I concentrate on flavor changing neutral current processes and compare our ability to extract short distance physics in the three cases. Finally, I give some examples of the sensitivity of these decays to extensions of the standard model.Comment: 12 pages, 4 figures. Talk presented at the Workshop on Heavy Quarks at Fixed Target, Fermilab, Batavia IL, October 10-12, 199

Rare Charm Decays

Rare FCNC decay modes of charmed mesons are reviewed. The standard model predictions, including both short and long distance contributions, are summarized. Several new physics options that can give detectable signals are described.Comment: 4 pages. Presented at the 6th International Conference on Hyperons, Charm and Beauty Hadrons, IIT, Chicago, june 27-july 3, 2004. To be published in the Proceeding

Current Topics in D0 B Physics

An overview of selected topics in DO B-Physics is presented, covering relevant detector characteristics, and with emphasis on the most recent results in the Bs, FCNC and rare decay programs.Comment: 4 pages, 3 figures, for the D0 Collaboration, 10th International Conference on B-Physics at Hadron Machines - BEAUTY 2005 - June 20 to 24, 2005 in Assisi, Ital