In quest of "just" the Standard Model on D-branes at a singularity

In this note we explore the possibility of obtaining gauge bosons and fermionic spectrum as dose as possible to the Standard Model content, by placing D3-branes at a ℤN orbifold-like singularity in the presence of D7-branes. Indeed, we find that this is plausible provided a sufficiently high N is allowed for and the singular point is also fixed by an orientifold action. If extra charged matter is not permitted then the singularity should necessarily be non-supersymmetric. Correct hypercharge assignments require a dependence on some abelian gauge D7-groups. In achieving such a construction we follow a recent observation made in ref. about the possibility that, the three left handed quarks, would present different U(2) transformation properties. © SISSA/ISAS 2002.