Sparticle Spectrum of Large Volume Compactification

TL;DR

The work investigates sparticle spectra in large volume compactifications (LVS) of Type IIB string theory, incorporating loop-induced moduli mixing from radiative corrections to the Kähler potential. It demonstrates that when the visible sector cycle is stabilized by a $D$-term from an anomalous U(1) symmetry, soft scalar masses receive a $D$-term contribution of order $m_{3/2}$, while moduli-mediated gaugino masses and A-terms remain loop-suppressed at order $m_{3/2}/(8\pi^2)$; excessive moduli mixing can destabilize the LVS minimum. The paper also presents a concrete D-term stabilization scheme for the MSSM cycle, with an intermediate axion scale $M_{PQ}$ generated by a PQ sector and a low-energy effective theory obtained after integrating out heavy fields. Anomaly mediation is found to be negligible due to the no-scale structure, leading to a characteristic loop-hierarchy in the soft spectrum: scalars $\sim m_{3/2}$ and gauginos $\sim m_{3/2}/8\pi^2$. The results imply that achieving TeV-scale soft terms with a Planck-scale cosmological constant generally requires multi-TeV gravitino mass, influencing the possible string scale and unification picture in LVS scenarios.

Abstract

We examine the large volume compactification of Type IIB string theory or its F theory limit and the associated supersymmetry breakdown and soft terms. It is crucial to incorporate the loop-induced moduli mixing, originating from radiative corrections to the Kahler potential. We show that in the presence of moduli mixing, soft scalar masses generically receive a D-term contribution of the order of the gravitino mass m_{3/2} when the visible sector cycle is stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while the moduli-mediated gaugino masses and A-parameters tend to be of the order of m_{3/2}/8pi^2. It is noticed also that a too large moduli mixing can destabilize the large volume solution by making it a saddle point.