BPS states of strings in 3-form flux

We count the Bogomol'nyi-Prasad-Sommerfield (BPS) states of strings in uniform 3-form fluxes, using supersymmetric quantum mechanics derived from the κ-symmetric action for D-branes. This problem is relevant to the stringy physics of warped compactifications. We work on a type IIB T6/Z2 orientifold with an imaginary self-dual, quantized, 3-form flux. Ignoring the orientifold projection, the number of short multiplets living on a single string is the square of the units of the 3-form flux present on the torus; the orientifold removes roughly half of the multiplets. We review the well-known case of a superparticle on T2 as a pedagogical example