Wilson Loops for a quark anti-quark pair in D3-brane space

We calculate static Wilson loops for a heavy quark anti-quark pair in different positions in the space generated by a large number of coincident D3-branes. Simple results are obtained from limiting cases of the geodesic shape. In particular, quark anti-quark static potentials for flat and AdS spaces are reproduced.Comment: Revised version published in JHE

Gauge/string duality and hadronic physics

We review some recent results on phenomenological approaches to strong interactions inspired in gauge/string duality. In particular, we discuss how such models lead to very good estimates for hadronic masses.Comment: 5pages, talk presented in I Latin American Workshop on High Energy Phenomenology, Porto Alegre, Brazil, December 2005, to appear in the proceeding

Remarks on gauge fixing and BRST quantization of noncommutative gauge theories

We consider the BRST gauge fixing procedure of the noncommutative Yang-Mills theory and of the gauged U(N) Proca model. An extended Seiberg-Witten map involving ghosts, antighosts and auxiliary fields for non Abelian gauge theories is studied. We find that the extended map behaves differently for these models. For the Yang-Mills theory in the Lorentz gauge it was not possible to find a map that relates the gauge conditions in the noncommutative and ordinary theories. For the gauged Proca model we found a particular map relating the unitary gauge fixings in both formulations.Comment: 8 pages, no figures. In this revised version, we included the explicit Seiberg Witten maps for antighost and auxiliary fields. We used this expressions to show that it is not possible to relate the Lorentz gauge in noncommutative and ordinary YM theories by the SW map, as claimed in the previous versio