Journal of High Energy Physics

, 2011:108

First online:

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UV-completion by classicalization

  • Gia DvaliAffiliated withArnold Sommerfeld Center for Theoretical Physics, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenMax-Planck-Institut für PhysikCERN, Theory DivisionCCPP, Department of Physics, New York University
  • , Gian F. GiudiceAffiliated withCERN, Theory Division Email author 
  • , Cesar GomezAffiliated withInstituto de Física Teórica UAM-CSIC, C-XVI, Universidad Autónoma de Madrid
  • , Alex KehagiasAffiliated withPhysics Division, National Technical University of Athens


We suggest a novel approach to UV-completion of a class of non-renormalizable theories, according to which the high-energy scattering amplitudes get unitarized by production of extended classical objects (classicalons), playing a role analogous to black holes, in the case of non-gravitational theories. The key property of classicalization is the existence of a classicalizer field that couples to energy-momentum sources. Such localized sources are excited in high-energy scattering processes and lead to the formation of classicalons. Two kinds of natural classicalizers are Nambu-Gold stone bosons (or, equivalently, longitudinal polarizations of massive gauge fields) and scalars coupled to energy-momentum type sources. Classicalization has interesting phenomenological applications for the UVcompletion of the Standard Model both with or without the Higgs. In the Higgless Standard Model the high-energy scattering amplitudes of longitudinal W -bosons self-unitarize via classicalization, without the help of any new weakly-coupled physics. Alternatively, in the presence of a Higgs boson, classicalization could explain the stabilization of the hierarchy. In both scenarios the high-energy scatterings are dominated by the formation of classicalons, which subsequently decay into many particle states. The experimental signatures at the LHC are quite distinctive, with sharp differences in the two cases.


Phenomenological Models