U(1)'S from Intersecting D-Branes

Intersecting D-brane model building is an exciting new direction in string phenomenology. A common characteristic of these models is the appearance of several U(1) factors. In this talk we show how to diagonalize the U(1) gauge sector of a class of intersecting D-brane models that appeared recently in the literature, even though most of our formulae can be applied in a more general context.