### Orientifold Defects in Conformal Field Theory and Holography

I introduce a new class of defects in conformal field theory (CFT), termed orientifold defects. These defects arise from quotienting the spacetime by a Z_2 automorphism, and provide higher-codimension generalizations of CFT on a real projective space (RP_d). The orientifold defects of codimension-p preserve the SO(d-p-1)xSO(p) subgroup of the conformal group, and the two-point functions of local operators in their presence satisfy the orientifold crossing equation, which we present. In contrast to standard conformal defects, both channels of the crossing equation involve bulk operators only, and operators localized on the defect are absent. I will then present a classification of half-BPS orientifold defects in N=4 SYM and provide evidence that they preserve integrability of planar N=4 SYM and are holographic dual to orientifolds in type IIB string theory on AdS_5 times S^5.

**5 December 2023, 14:00**