Scale-separated AdS$_4$ vacua of IIA orientifolds and M-theory

Understand

We revisit various aspects of AdS$_4$ flux vacua with scale separation in type II supergravity and M-theory.

• We show that massless IIA allows both weakly and strongly coupled solutions for which the classical orientifold backreaction can be tuned small.
• This is explicitly verified by computing the backreaction at leading order in perturbation theory.
• We give evidence that the strongly coupled solutions can be lifted to scale-separated and sourceless (but classically singular) geometries in 11D supergravity.