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In a recent paper [1] it was shown that in fluxless M theory vacua with at least two hidden sectors undergoing strong gauge dynamics and a particular form of the Kähler potential, all moduli are stabilized by the effective potential and a stable hierarchy is generated, consistent with standard gauge unification. This paper explains the results of [1] in more detail and generalizes them, finding an essentially unique de Sitter (dS) vacuum under reasonable conditions. One of the main phenomenological consequences is a prediction which emerges from this entire class of vacua: namely gaugino masses are significantly suppressed relative to the gravitino mass. We also present evidence that, for those vacua in which the vacuum energy is small, the gravitino mass, which sets all the superpartner masses, is automatically in the TeV -100 TeV range.

We address the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli. The main examples we study are the G 2 -MSSM models arising from M theory compactifications, which allow for a precise calculation of moduli decay rates and widths. We find that the late decaying moduli satisfy both BBN constraints and avoid the gravitino problem. The non-thermal production of Wino LSPs, which is a prediction of G 2 -MSSM models, gives a relic density of about the right order of

An old idea for explaining the hierarchy is strong gauge dynamics. We show that such dynamics also stabilizes the moduli in M theory compactifications on manifolds of G2-holonomy without fluxes. This gives stable vacua with softly broken susy, grand unification and a distinctive spectrum of TeV and sub-TeV sparticle masses. .Jv 14.80.Ly Stabilizing Hierarchies and ModuliM theory (and its weakly coupled string limits) is a consistent quantum theory including gravity, particle physics and much more. Although apparently unique, the theory has a large number of solutions, manifested by the presence of moduli: massless scalar fields with classically undetermined vacuum expectation values (vevs), whose values determine the masses and coupling constants of the low energy physics.In recent years, there has been substantial progress in understanding mechanisms which stabilize moduli in various corners of the M theory moduli space. In particular, the stabilization of all moduli by magnetic fields (fluxes) in the extra dimensions, perhaps also combined with other quantum effects, has been reasonably well understood in the context of Type IIB string theory [1,2], M theory [3] and Type IIA string theory [4]. After stabilizing the moduli, one still has to explain why M W /m pl ∼ 10 −16 . The effective potential of these compactifications fits into the framework of a low energy supergravity theory in four dimensions. A well known property of the latter is that there is a universal contribution to scalar masses of order the gravitino mass m 3/2 . Therefore, without miraculous cancellations, in theories in which m 3/2 is large, the Higgs mass is also large. In M theory and Type IIA flux vacua the vacuum superpotential is O(1) or larger in Planck units. This gives a large m 3/2 (unless the volume of the extra dimensions is large, ruining standard unification). In heterotic flux vacua [5] m 3/2 can be smaller, but only by a few orders of magnitude. Thus, in these vacua, stabilizing the moduli using fluxes fails to solve the hierarchy problem, viz. to generate and stabilize the hierarchy between the electroweak and Planck scales.In Type IIB theory, this is not so: m 3/2 can be tuned small by choosing fluxes. One can also address the possibility of generating the hierarchy through warping [6] in this framework [1]. The hierarchy problem is less well understood in other corners of the M theory moduli space.Our focus will be M theory, and we will henceforth switch off all the fluxes else the hierarchy will be destroyed. Supersymmetry then implies that the seven extra dimensions form a space X with G 2 -holonomy. In these vacua, non-Abelian gauge fields are localized along three dimensional submanifolds Q ⊂ X at which there is an orbifold singularity [7] and chiral fermions are localized at points at which there are conical singularities [8,9,10].These vacua can have interesting phenomenological features, independently of how moduli are stabilized: the Yukawa couplings are hierarchical; proton decay proceeds at dimension six with disti...

We continue our study of the low energy implications of M theory vacua on G 2 manifolds, undertaken in [1,2], where it was shown that the moduli can be stabilized and a TeV scale generated, with the Planck scale as the only dimensionful input. A well-motivated phenomenological model -the G 2 -MSSM, can be naturally defined within the above framework. In this paper, we study some of the important phenomenological features of the G 2 -MSSM. In particular, the soft supersymmetry breaking parameters and the superpartner spectrum are computed. The G 2 -MSSM generically gives rise to light gauginos and heavy scalars with wino LSPs when one tunes the cosmological constant. Electroweak symmetry breaking is present but fine-tuned. The G 2 -MSSM is also naturally consistent with precision gauge coupling unification. The phenomenological consequences for cosmology and collider physics of the G 2 -MSSM will be reported in more detail soon.

Light scalar fields with only gravitational strength couplings are typically present in UV complete theories of physics beyond the Standard Model. In the early universe it is natural for these fields to dominate the energy density, and their subsequent decay -if prior to BBN -will typically yield some dark matter particles in their decay products. In this paper we make the observation that a Non-thermal WIMP 'Miracle' may result: that is, in the simplest solution to the cosmological moduli problem, non-thermally produced WIMPs can naturally account for the observed dark matter relic density. Such a solution may be generic in string theory compactifications.

Abstract:We give an explicit realization of the "String Axiverse" discussed in Arvanitaki et. al [1] by extending our previous results on moduli stabilization in M theory to include axions. We extend the analysis of [1] to allow for high scale inflation that leads to a moduli dominated pre-BBN Universe. We demonstrate that an axion which solves the strong-CP problem naturally arises and that both the axion decay constants and GUT scale can consistently be around 2 × 10 16 GeV with a much smaller fine tuning than is usually expected. Constraints on the Axiverse from cosmological observations, namely isocurvature perturbations and tensor modes are described. Extending work of Fox et. al [2], we note that the observation of tensor modes at Planck will falsify the Axiverse completely. Finally we note that Axiverse models whose lightest axion has mass of order 10 −15 eV and with decay constants of order 5 × 10 14 GeV require no (anthropic) fine-tuning, though standard unification at 10 16 GeV is difficult to accommodate.

We present a systematic cosmological study of a universe in which the visible sector is coupled, albeit very weakly, to a hidden sector comprised of its own set of particles and interactions. Assuming that dark matter (DM) resides in the hidden sector and is charged under a stabilizing symmetry shared by both sectors, we determine all possible origins of weak-scale DM allowed within this broad framework. We show that DM can arise only through a handful of mechanisms, lending particular focus to Freeze-Out and Decay and Freeze-In, as well as their variations involving late time re-annihilations of DM and DM particle anti-particle asymmetries. Much like standard Freeze-Out, where the abundance of DM depends only on the annihilation cross-section of the DM particle, these mechanisms depend only on a very small subset of physical parameters, many of which may be measured directly at the LHC. In particular, we show that each DM production mechanism is associated with a distinctive window in lifetimes and cross-sections for particles which may be produced in the near future. We evaluate prospects for employing the LHC to definitively reconstruct the origin of DM in a companion paper.