We study parity symmetries and boundary conditions in the framework of gauged linear sigma models. This allows us to investigate the Kähler moduli dependence of the physics of D-branes as well as orientifolds in a Calabi–Yau compactification. We first determine the parity action on D-branes and define the set of orientifold-invariant D-branes in the linear sigma model. Using probe branes on top of orientifold planes, we derive a general formula for the type (SO versus Sp) of orientifold planes. As applications, we show how compactifications with and without vector structure arise naturally at different real slices of the Kähler moduli space of a Calabi–Yau compactification. We observe that orientifold planes located at certain components of the fixed-point locus can change type when navigating through the stringy regime.
"Orientifolds and D-branes in $N=2$ gauged linear sigma models." Adv. Theor. Math. Phys. 14 (4) 1001 - 1088, August 2010.