Fermions and gauge bosons in $SU(4)_L \times U(1)_X$ models with little   Higgs
  We discuss the aspects of the little Higgs model with the $SU(4)_L \times U(1)_X$ electroweak gauge group as an alternative solution to the naturalness and fine-tuning issues. We introduce anomaly-free fermion spectra, and present their interactions with the physical gauge bosons. We also discuss some phenomenological implications of these fermions and the extra gauge bosons based on recent experimental results. 
Soo-hyeon Nam