1 / 27

Tree-level unitarity in Gauge-Higgs Unification

Tree-level unitarity in Gauge-Higgs Unification. Yutaka Sakamura (KEK) with Naoyuki Haba (Osaka Univ.) and Toshifumi Yamashita (Nagoya Univ.) January 20, 2010 @ Osaka Univ. arXiv:0908.1042. Introduction. Standard model. Electroweak sym. breaking, (perturbative) unitarity. Higgs boson.

dallon
Télécharger la présentation

Tree-level unitarity in Gauge-Higgs Unification

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Tree-level unitarity in Gauge-Higgs Unification Yutaka Sakamura (KEK) with Naoyuki Haba (Osaka Univ.)and Toshifumi Yamashita (Nagoya Univ.)January 20, 2010 @ Osaka Univ. arXiv:0908.1042

  2. Introduction

  3. Standard model Electroweak sym. breaking,(perturbative) unitarity Higgs boson e.g.) + +

  4. w/o Higgs Unitaritybound w/ Higgs 1 TeV If the WWH coupling vanishes, the Higgs boson cannot contribute to the unitarization. This occurs in the Gauge-Higgs Unification modelsin the warped spacetime.

  5. Tree-level unitarity will be violated at some scale. From naïve dimensional analysis, Purpose • We numerically estimate • scattering amplitudes for W, Z bosons • a scale at which the tree-level unitarity is violated in the Gauge-Higgs Unification. Extra-dimensional models are non-renormalizable.

  6. Models with extra dimension Boundary conditionsalong the extra dimension EW breaking Higgsless model [Csaki, et.al, 2003] Unitarity is recovered by KK gauge bosons Gauge-Higgs Unification [Fairlie; Manton, 1979; Hosotani, 1983,…] Higgs Unitarity is recovered by KK gauge bosonsand zero-mode of

  7. Gauge-Higgs Unificationin warped spacetime Wilson line phase: Contribution to the saturation of amplitudes Higgs KK modes main less less main [Falkowski, Pokorski, Roberts, 2007]

  8. Set up

  9. tuning q w suppressing T-parameter SO(5)xU(1) model on S /Z 1 2 [Agashe, Contino, Pomarol, 2005] Planck brane TeV brane

  10. = Higgs doublet determined by quantum effect Gauge symmetry : SO(4) zero-modes Wilson line phase:

  11. WWH, ZZH couplings Flat case These are the same as the SM values. Warped case [Hosotani & Y.S., 2006-2007]

  12. Weak boson scattering

  13. Equivalence Theorem As an example, we consider . Equivalence theorem

  14. Scattering amplitude Metric

  15. For , each coupling deviates from the SM value. [Hosotani & Y.S., 2007] Flat case Warped case

  16. In the unit of the KK scale , The amplitude stops growing when the KK modes start to propagate.

  17. Unitarity violation

  18. Unitarity condition elastic scattering involving KK modes where (S-wave amplitude)

  19. Unitarity violation scale L uni

  20. unitarity cond.

  21. c.f. unitarity cond.

  22. Summary • Weak boson scattering in GHU model • Equivalence theorem holds well. • Amplitudes have large -dependencein the warped spacetime. • Tree-level unitarity is violated at

  23. e.g.) 5D propagator [Gherghetta & Pomarol, 2001] (written by Bessel functions) Advantages We can calculate the amplitudes without • the knowledge of the KK mass eigenvalues • summation over infinite KK modes

  24. In the conventional KK expansion, where where

  25. For the 2 →2 channel, Then we obtain Unitarity condition

  26. If we assume that the S-wave component is dominant, we obtain

  27. translated into a cut-off for f Comment on Thus, the S-wave amplitude diverges. Taking into account the width of the W boson, the divergence at is smeared out.

More Related