Dynamics of unitarization by classicalization

Gia Dvali, David Pirtskhalava

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We study dynamics of the classicalization phenomenon suggested in G. Dvali et al. [1], according to which a class of non-renormalizable theories self-unitarizes at very high-energies via creation of classical configurations (classicalons). We study this phenomenon in an explicit model of derivatively-self-coupled scalar that serves as a prototype for a Nambu-Goldstone-Stückelberg field. We prepare the initial state in form of a collapsing wave-packet of a small occupation number but of very high energy, and observe that the classical configuration indeed develops. Our results confirm the previous estimates, showing that because of self-sourcing the wave-packet forms a classicalon configuration with radius that increases with center of mass energy. Thus, classicalization takes place before the waves get any chance of probing short-distances. The self-sourcing by energy is the crucial point, which makes classicalization phenomenon different from the ordinary dispersion of the wave-packets in other interacting theories. Thanks to this, unlike solitons or other non-perturbative objects, the production of classicalons is not only unsuppressed, but in fact dominates the high-energy scattering. In order to make the difference between classicalizing and non-classicalizing theories clear, we use a language in which the scattering cross section in a generic theory can be universally understood as a geometric cross section set by a classical radius down to which waves can propagate freely, before being scattered. We then show, that in non-classicalizing examples this radius shrinks with increasing energy and becomes microscopic, whereas in classicalizing theories expands and becomes macroscopic. We study analogous scattering in a Galileon system and discover that classicalization also takes place there, although somewhat differently. We thus observe, that classicalization is source-sensitive and that Goldstones pass the first test.

    Original languageEnglish (US)
    Pages (from-to)78-86
    Number of pages9
    JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
    Volume699
    Issue number1-2
    DOIs
    StatePublished - May 2 2011

    Keywords

    • Classicalization
    • Goldstone bosons
    • Unitarization

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics

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