Related papers: A Large Mass Hierarchy from a Small Extra Dimensio…
Models with large extra dimensions offer the possibility of the Planck scale being of order the electroweak scale, thus alleviating the gauge hierarchy problem. We show that these models suffer from a breakdown of unitarity at around three…
It has been proposed that, without invoking supersymmetry, it is possible to solve the hierarchy problem provided the fundamental scale in the higher dimensional theory is at a much lower scale than the Planck scale. In this paper we…
We construct a model consisting of many D3-branes with only positive tension in a five-dimensional anti-de Sitter space-time geometry. It is shown that this type of model naturally realizes not only exponential mass hierarchy between the…
The nature of gravity and its strength compared with other forces are fundamental challenges faced by the actual science. A path to understanding the hierarchy problem of gravity consists in adding an extra dimension to Einstein-Hilbert's…
Combining the quantum scale invariance with the absence of new degrees of freedom above the electroweak scale leads to stability of the latter against perturbative quantum corrections. Nevertheless, the hierarchy between the weak and the…
We consider theories in which the Standard Model gauge fields propagate in extra dimensions whose size is around the electroweak scale. The Standard Model quarks and leptons may either be localized to a brane or propagate in the bulk. This…
The hierarchy problem between the electroweak (EW) and Planck scales remains a central puzzle in modern physics. We discuss a promising solution operating through the cosmological selection of the EW vacuum in a multiverse landscape, where…
We propose a framework in which Weinberg's anthropic explanation of the cosmological constant problem also solves the hierarchy problem. The weak scale is selected by chiral dynamics that controls the stabilization of an extra dimension.…
Warped extra dimension claims remarkable success: solving the hierarchy problem; explaining hierarchies in particle phenomenology; yielding standard cosmology, plus interesting nonstandard scenarios. Yet it has marked shortcomings: we…
We construct the general model with only parallel positive tension 3-branes on $M^4 \times R^1$ and $M^4 \times R^1/Z_2$. The cosmology constant is sectional constant along the fifth dimension. In this general scenario, the 5-dimensional…
Five-dimensional scenarios with infinitesimally thin branes replaced by appropriate configurations of a scalar field were considered. A possibility of periodic extra dimension was discussed in the presence on non-minimal scalar-gravity…
In sufficiently complex models with many parameters that are unknown or undetermined from first principles, a small coupling or mass can naturally arise even if it is not protected by a symmetry or a result of some dynamics. For the…
In the standard model in universal extra dimensions (UED) the mass of the Higgs field is driven to the cutoff of the higher-dimensional theory. This re-introduces a small hierarchy since the compactification scale 1/R should not be smaller…
Why are the cosmological constant, electroweak and Planck scales so different? This ``double hierarchy" problem, where $\Lambda \ll M^2_{EW} \ll M^2_p$, is one of the most pressing in fundamental physics. We show that in a theory of $N$…
Five-dimensional models where the bulk is a slice of AdS have the virtue of solving the hierarchy problem. The electroweak scale is generated by a ``warp'' factor of the induced metric on the brane where the standard model fields live.…
Scale invariance may be a classical symmetry which is broken radiatively. This provides a simple way to stabilise the scale of electroweak symmetry breaking against radiative corrections. But for such a theory to be fully realistic, it must…
If scale invariance is a classical symmetry then both the Planck scale and the weak scale should emerge as quantum effects. We show that this can be realized in simple scale invariant theories with a hidden sector. The weak/Planck scale…
Recently it was proposed that the standard model (SM) degrees of freedom reside on a $(3+1)$-dimensional wall or ``3-brane'' embedded in a higher-dimensional spacetime. Furthermore, in this picture it is possible for the fundamental Planck…
In the underlying Planck scale theory we introduce a certain type of discrete symmetry, which potentially brings the stability of the weak-scale hierarchy under control. Under the discrete symmetry the $\mu $-problem and the tadpole problem…
We consider an extension of the Randall-Sundrum model with three parallel 3-branes in a 5-dimensional spacetime. This new construction, apart from providing a solution to the Planck hierarchy problem, has the advantage that the SM fields…