Exponentially Small Supersymmetry Breaking from Extra Dimensions

The supersymmetric “shining” of free massive chiral superfields in extra dimensions from a distant source brane can trigger exponentially small supersymmetry breaking on our brane of order e−2πR, where R is the radius of the extra dimensions. This supersymmetry breaking can be transmitted to the superpartners in a number of ways, for instance by gravity or via the standard model gauge interactions. The radius R can easily be stabilized at a size O(10) larger that the fundamental scale. The models are extremely simple, relying only on free, classical bulk dynamics to solve the hierarchy problem. 1 The four forces of nature are each characterized by a mass scale: √ 1/GN = MP ≈ 10 GeV for gravity, ΛW ≈ 10 GeV for the weak interaction, ΛQCD ≈ 0.1 GeV for the strong interaction and mγ = 0 for the electromagnetic interaction. What is the origin of these diverse scales? Over the last 25 years a single dominant viewpoint has developed: the largest scale, that of gravity, is fundamental, and the other scales are generated by a quantum effect in gauge theories known as dimensional transmutation. If the coupling strengths of the other forces have values αP ≈ 1/30 at the fundamental scale, then a logarithmic evolution of these coupling strengths with energy leads, in nonAbelian theories, to the generation of a new mass scale