Subleading corrections to F-terms in the Large Volume Scenario

In Large Volume Scenarios, the axio-dilaton and complex-structure F-terms receive non-vanishing contributions from several subleading effects, some of which have already been extensively studied in the literature. For instance, the inverse of the corrected Kahler metric induces mixing between the axio-dilaton S and the Kahler directions Ti. Since DTi W is non-zero at the LVS AdS minimum, this mixing generates non-vanishing F-terms for both S and za. In addition, the perturbative correction to the Kahler potential directly modifies the covariant derivatives DTi , DS, and Dza. Also the dependence of Wnp on za and S via its prefactor: Wnp = A(za, S)e−aiT i leads the F-terms to acquire non-zero contributions. In this thesis, we investigate a distinct contribution arising from the displacement of the axio-dilaton and complex-structure moduli away from their supersymmetric tree-level flux vacuum. Although these fields are conventionally stabilised at leading order and subsequently treated as frozen in the analysis of Kahler-moduli stabilisation, the perturbative and non-perturbative effects responsible for the Large Volume Scenario generate non-vanishing gradients along the (S, za) directions. As a consequence, the full minimum is shifted by amounts δS and δza. We compute these displacements perturbatively in the large-volume and weak-coupling regime, organising the results according to their parametric scaling in inverse powers of the compactification volume V and powers of the string coupling gs. We then determine how the shifted vacuum modifies the corresponding F-terms. The analysis is first performed in a simplified model with rigid complex-structure and subsequently extended to a model containing a dynamical complex-structure modulus. We find that the shift-induced contribution to the complex-structure sector F-term is enhanced by an additional factor of g−1 s relative to the previously known contributions and can therefore become parametrically dominant in the weak-coupling regime. By contrast, the corresponding contribution to the axio-dilaton F-term is generically of the same parametric order in gs and V−1 as the contributions already discussed in the literature. We also discuss the phenomenological implications of these corrections for soft supersymmetry-breaking terms in sequestered LVS scenarios. In particular, while soft terms controlled by F S remain parametrically unchanged, the modified complex-structure F-terms can lead to parametrically different contributions to scalar masses in the ultra-local regime and to the masses of hidden RR photini.