Wall Crossing Phenomenology of Orientifolds

We initiate the study of wall crossing phenomena in orientifolds of local toric Calabi-Yau 3-folds from a topological string perspective. For this purpose, we define a notion of real Donaldson-Thomas partition function at the large volume, orbifold and non-commutative point in Kaehler moduli space. As a byproduct, we refine the constant map contribution to the partition function of the real topological string on a local toric background. We conjecture the general relation between the real large volume and real non-commutative/orbifold Donaldson-Thomas partition function of orientifolds of local toric Calabi-Yau 3-folds without compact divisors. The conjectured relation is confirmed at hand of the conifold and local A_n singularity, for which we explicitly derive the real non-commutative/orbifold Donaldson-Thomas partition function combinatorially.