No-scale and scale-separated flux vacua from IIA on G2 orientifolds

Abstract

We discuss flux compactifications of IIA string theory on G2 holonomy spaces with O2/O6-planes to three dimensions and find two classes of solutions: (1) No-scale Minkowski vacua from NSNS 3-form fluxes and RR 4-form fluxes. (2) By adding Romans mass we find AdS$$_3$$ 3 vacua for which the AdS scale can be decoupled completely from the KK scale while the solution is at tunable weak coupling and large volume. For the AdS$$_3$$ 3 vacuum we only have a proper 3D description (i.e. smeared orientifold description) of the solution like the 4D analogue of IIA moduli stabilization from fluxes and O6-planes. This 3D description reveals that moduli with non-compact moduli spaces can be stabilized at the classical level. For both types of vacua we can have supersymmetry or not.

Three-dimensional flux vacua from IIB on co-calibrated G2 orientifolds

“…For the reasons outlined above, in this work we continue the study of Type II string flux compactifications with threedimensional external space and minimal supersymmetry, that was initiated in [14,15]. As shown in those works, Type II on G2 holonomy manifolds has offered the possibility to scrutinize the swampland conjectures.…”

“…It is important to point out that the non-vanishing covariant derivative ∇ = 0 signifies a deviation from G2 holonomy and implies a non-vanishing Ricci tensor which is a key feature of this work. Previous works [14,15] studied the case where ∇ = 0 and thus all torsions were simultaneously set to zero, the internal space was Ricci flat and the G2 structure group was equivalent to the G2 holonomy of the manifold. Here instead the form of the Ricci scalar is R (7)…”

“…Now we would like to turn the discussion to the relation of the orientifolds and the orbifold group . In [14] we worked with Type IIA and space-filling O2-planes, however now the presence of both torsion and O2-planes is forbidden by the Maurer-Cartan equation, which automatically sets the structure constants to zero and brings us back to G2 holonomy. Here instead we will focus on Type IIB where we can have O3, O5, O7 and O9-planes.…”

“…This procedure is completely consistent because of the specific properties of our superpotential, otherwise such procedure would not preserve supersymmetry. In particular it was proven in [14] that a sufficient condition for doing this is…”

“…As a result the properties of such vacua can be cross-checked with 2D CFT methods. Secondly, from a technical point of view, the field content of a 3D flux compactification is considerably simpler than the 4D counter-parts which allows to perform a more thorough study of such vacua [14,15]. For example, the minimal supersymmetric background in 3D allows half of the number of supersymmetries than the minimal 4D background.…”