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31 July, 2016

posted 31 Jul 2016, 01:40 by Scott Melville   [ updated 31 Jul 2016, 10:13 ]
Strong Coupling and Classicalization
(24 pages)

Instead of the usual Wilsonian UV-completion, which integrates in new weakly-coupled degrees of freedom, an alternative is self-completion and classicalization, which uses states of high multiplicity of the existing low-energy degrees of freedom. In scattering experiments, this produces a tower of resonances ('classicalons'). At higher masses, the classicalon is longer-lived and behaves `more classically'. The hierarchy problem in the Standard model (assuming there isn't just some judicious vacuum-selection) is the result of new physics, possibly around the TeV scale, which is either weakly- or strongly-coupled. If we assume strongly-coupled, then any detection of new resonances around TeV scales could be interpreted as classicalons, and lend support to the hypothesis that classicalization is taking place.


Classicalization is the process by which a strongly coupled regime can be avoided by redistributing high energies into a large number of weakly-interacting soft quanta. It is useful in many problems, the archetypal example being black hole formation in high energy scattering processes (the black holes then Hawking radiate energy into a huge number of low energy photons). At very high energy, the classicalization process generates states with ever larger occupation numbers, increasingly classical states. The main proposal here is that the LHC may stand a chance of detecting such classical states, which would appear as a tower of resonances at and above the strong coupling scale.

General background conditions for K-bounce and adiabaticity
(14 pages)

By demanding two turning points of the Hubble parameter in a single scalar field cosmlogy, conditions can be placed on the scalar kinetic and potential terms. In order to avoid discontinuities in the scalar field, the kinetic term is taken to be non-analytic, K(X) = X + X1/2. It is argued that for constant potentials, the perturbations are adiabatic at all scales, while for non-constant potentials, large non-adiabatic perturbations grow and source anisotropy.


Looking at the background equations of motion, one can infer conditions on the scalar field dynamics which must be satisfied if it is to drive a successful FRW bounce. Whether or not perturbations around these backgrounds are stable is an important question which is left for future work.