Hi everyone, I was wondering what ways there are to get rid of non-chiral matter in string theory. If you have a D7 brane in a type IIB orientifold with a flux on its world-volume you always get non-chiral matter. (In the IIA dual you have the brane and its image lying on top of each other in one torus if you have a toroidal compactification). What ways are there to make it massive or what other possibilites exist? Or would it be possible to still make it chiral in some way by an appropriate choice of groups or fluxes? Even a partial response is appreciated!