The Littlest Higgs
Abstract
We present an economical theory of natural electroweak symmetry breaking, generalizing an approach based on deconstruction. This theory is the smallest extension of the Standard Model to date that stabilizes the electroweak scale with a naturally light Higgs and weakly coupled new physics at TeV energies. The Higgs is one of a set of pseudo Goldstone bosons in an SU(5)/SO(5) nonlinear sigma model. The symmetry breaking scale f is around a TeV, with the cutoff Λlesssim4πf ~ 10 TeV. A single electroweak doublet, the `little Higgs', is automatically much lighter than the other pseudo Goldstone bosons. The quartic selfcoupling for the little Higgs is generated by the gauge and Yukawa interactions with a natural size Script O(g^{2}, λ_{t}^{2}), while the top Yukawa coupling generates a negative mass squared triggering electroweak symmetry breaking. Beneath the TeV scale the effective theory is simply the minimal Standard Model. The new particle content at TeV energies consists of one set of spin one bosons with the same quantum numbers as the electroweak gauge bosons, an electroweak singlet quark with charge 2/3, and an electroweak triplet scalar. One loop quadratically divergent corrections to the Higgs mass are cancelled by interactions with these additional particles.
 Publication:

Journal of High Energy Physics
 Pub Date:
 July 2002
 DOI:
 10.1088/11266708/2002/07/034
 arXiv:
 arXiv:hepph/0206021
 Bibcode:
 2002JHEP...07..034A
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 15 pages. References added. Corrected typos in the discussion of the top Yukawa coupling