Particle theory

Abstract:

We derive the perturbative four-dimensional effective theory describing heterotic M theory with branes and antibranes in the bulk space. The backreaction of both the branes and antibranes is explicitly included. To first order in the heterotic S expansion, we find that the forces on branes and antibranes vanish and that the Kachru-Kallosh-Linde-Trivedi (KKLT) procedure of simply adding to the supersymmetric theory the probe approximation to the energy density of the antibrane reproduces the correct potential. However, there are additional nonsupersymmetric corrections to the gauge-kinetic functions and matter terms. The new correction to the gauge-kinetic functions is important in a discussion of moduli stabilization. At second order in the S expansion, we find that the forces on the branes and antibranes become nonvanishing. These forces are not precisely in the naive form that one may have anticipated and, being second order in the small parameter S, they are relatively weak. This suggests that moduli stabilization in heterotic models with antibranes is achievable. © 2007 The American Physical Society.

Abstract:

We present numerical evidence for the spontaneous breaking of the ZN4 symmetry of four-dimensional twisted Eguchi-Kawai models with SU(N) gauge group and symmetric twist, for sufficiently large N. We find that for N ≥ 100 this occurs for a wide range of bare couplings. Moreover for N ≤ 144, where we have been able to perform detailed calculations, there is no window of couplings where the physically interesting confined and deconfined phases appear in the reduced model. We provide a possible interpretation for this in terms of generalised 'fluxon' configurations. We discuss the implications of our findings for the validity and utility of space-time reduced models as N → ∞. © 2007 Elsevier B.V. All rights reserved.

Abstract:

We scan the landscape of flux compactifications for the Calabi-Yau manifold $\mathbb{P}^4_{[1,1,1,6,9]}$ with two K\" ahler moduli by varying the value of the flux superpotential $W_0$ over a large range of values. We do not include uplift terms. We find a rich phase structure of AdS and dS vacua. Starting with $W_0\sim 1$ we reproduce the exponentially large volume scenario, but as $W_0$ is reduced new classes of minima appear. One of them corresponds to the supersymmetric KKLT vacuum while the other is a new, deeper non-supersymmetric minimum. We study how the bare cosmological constant and the soft supersymmetry breaking parameters for matter on D7 branes depend on $W_0$, for these classes of minima. We discuss potential applications of our results.