Standard-like models from D-branes

Abstract

I describe the main features of new intersecting D4- and D5-brane orbifold models that yield the non-supersymmetric standard model, up to vector-like matter and, in some cases, extra U(1) factors in the gauge group. There are six-stack D4-brane models that have charged-singlet scalar tachyons and which either contain all of the Yukawa couplings to the tachyonic Higgs doublets that are needed to generate mass terms for the fermions at renormalisable level or possess an unwanted extra U(1) gauge symmetry after spontaneous symmetry breaking. In the D5-brane models a minimum of eight stacks is needed.