Phenomenology of Mixed Modulus-Anomaly Mediation in Fluxed String Compactifications and Brane Models

Abstract

In some string compactifications, for instance the recently proposed KKLT set-up, light moduli are stabilized by nonperturbative effects at supersymmetric AdS vacuum which is lifted to a dS vacuum by supersymmetry breaking uplifting potential. In such models, soft supersymmetry breaking terms are determined by a specific mixed modulus-anomaly mediation in which the two mediations typically give comparable contributions to soft parameters. Similar pattern of soft terms can arise also in brane models to stabilize the radion by nonperturbative effects. We examine some phenomenological consequences of this mixed modulus-anomaly mediation, including the pattern of low energy sparticle spectrum and the possibility of electroweak symmetry breaking. It is noted that adding the anomaly-mediated contributions at $M_{GUT}$ amounts to replacing the messenger scale of the modulus mediation by a mirage messenger scale $(m_{3/2}/M_{Pl})^{α/2}M_{GUT}$ where $α=m_{3/2}/[M_0\ln(M_{Pl}/m_{3/2})]$ for $M_0$ denoting the modulus-mediated contribution to the gaugino mass at $M_{GUT}$. The minimal KKLT set-up predicts $α=1$. As a consequence, for $α={\cal O}(1)$, the model can lead to a highly distinctive pattern of sparticle masses at TeV scale, particularly when $α= 2$.