Particle theory

Abstract:

We consider Einstein gravity coupled to a CFT made of a single free conformal scalar in AdS4. This simple case is rich enough to explain an unexpected gravitational Higgs phenomenon that has no flat-space counterpart, yet simple enough that many calculations can be carried on exactly. Specifically, in this Letter we compute the graviton self energy due to matter, and we exhibit its spectral representation. This enables us to find the spin-2 bound-state content of the system. © 2002 Elsevier Science B.V. All rights reserved.

Abstract:

In grand unified theories based on orbifold constructions in higher dimensions, Higgsino-mediated proton decay is absent. However, proton decay mediated by $X$ and $Y$ gauge bosons is typically enhanced to levels detectable by current and future experiments. We analyse the phenomenology of proton decay induced by the minimal coupling of $X,Y$ gauge bosons. In particular, we show that the novel realization of matter in orbifold GUTs can lead to unusual final state flavour structure, for example, the dominance of the $p\to K^0\mu^+$ mode. Furthermore, we discuss proton decay induced by higher-derivative brane operators, finding potentially observable rates for natural values of the operator coefficients.

Abstract:

In the context of brane-world theories, the production cross-section for black holes may be greatly enhanced. Such black holes can in principle lead to detectable signals via their Hawking evaporation to brane-localized modes. We calculate, in the semiclassical approximation, the leading corrections to the energy spectrum (the greybody factors) for decay into scalar fields, as a function of the number of toroidally compactified extra dimensions, and partial wave number.