Smoking-gun signatures of little Higgs models

TL;DR

Little Higgs theories address the hierarchy problem by making the Higgs a pseudo-Goldstone boson, with one-loop quadratic divergences canceled through collective symmetry breaking. The paper classifies realizations into product-group and simple-group classes, and derives testable LHC signatures in both the heavy quark sector (top partner $T$ and additional quarks) and the TeV-scale gauge sector (e.g., $W_H$, $Z_H$, $Z′$, $X$, $Y$), including mass relations, couplings, and decay patterns. It presents model-specific sum rules and observables that enable experimental verification of the divergence cancellation and the extended gauge structure, while offering strategies to distinguish little Higgs signals from fourth-generation top-primes and top see-saw scenarios. Overall, the work shows how combining measurements of the top sector and gauge sector at the LHC can confirm the little Higgs mechanism and identify the underlying gauge structure.

Abstract

Little Higgs models predict new gauge bosons, fermions and scalars at the TeV scale that stabilize the Higgs mass against quadratically divergent one-loop radiative corrections. We categorize the many little Higgs models into two classes based on the structure of the extended electroweak gauge group and examine the experimental signatures that identify the little Higgs mechanism in addition to those that identify the particular little Higgs model. We find that by examining the properties of the new heavy fermion(s) at the LHC, one can distinguish the structure of the top quark mass generation mechanism and test the little Higgs mechanism in the top sector. Similarly, by studying the couplings of the new gauge bosons to the light Higgs boson and to the Standard Model fermions, one can confirm the little Higgs mechanism and determine the structure of the extended electroweak gauge group.