MAGNETIZED TYPE I ORBIFOLDS IN FOUR DIMENSIONS

摘要

I review the basic features of four dimensional Z_2 x Z_2 (shift) ori-entifolds with internal magnetic fields, describing two examples with N = 1 su-persymmetry. As in the corresponding six-dimensional examples, D9-branes magnetized along four internal directions can mimic D5-branes, even in presence of multiplets of image branes localized on different fixed tori. Chiral low-energy spectra can be obtained if the model also contains D5-branes parallel to the magnetized directions.