The Little Higgs from a Simple Group

Abstract

We present a model of electroweak symmetry breaking in which the Higgs boson is a pseudo-Nambu-Goldstone boson. By embedding the standard model SU(2) x U(1) into an SU(4) x U(1) gauge group, one-loop quadratic divergences to the Higgs mass from gauge and top loops are canceled automatically with the minimal particle content. The potential contains a Higgs quartic coupling which does not introduce one-loop quadratic divergences. Our theory is weakly coupled at the electroweak scale, it has new weakly coupled particles at the TeV scale and a cutoff above 10 TeV, all without fine tuning. We discuss the spectrum of the model and estimate the constraints from electroweak precision measurements.

Figures (5)

• Figure 1: Quadratically divergent contributions to the Higgs mass in the Standard model: top loop, $SU(2)\times U(1)$ gauge boson loops and Higgs loop.
• Figure 2: $SU(3)$ gauge boson loop corrections to the ${\bf \Phi}$ mass.
• Figure 3: Gauge boson contributions to the ${\bf \Phi}$ potential in $\partial_\mu A^\mu =0$ gauge.
• Figure 4: The top loop contribution to the Higgs mass in sigma model formalism.
• Figure 5: The canceling top and $\chi$-loops in component form.