Little Higgs models were recently proposed as an alternative for models of electroweak symmetry breaking. They can be regarded as one of the important candidates of the new physics beyond the Standard Model. We consider here the phenomenology of the minimal model of this type, the "Littlest Higgs Model" (LHM). It predicts the existence of the new gauge bosons Z H and A H. We calculate the contributions of these new particles to the forward-backward and left-right asymmetries in the processes e+ + e- -> f + $ e^+ + e^- \longrightarrow f + \bar f $. We study the possibility of detecting the lightest new gauge boson, A H, in the future e+e- colliders with c.m. energies of 500 GeV and 1 TeV and compare the LHM predictions with other models.

There is a recent proposal of identifying the Higgs particle of the Standard Model as a pseudo Nambu-Goldstone boson. This new broken symmetry introduces new particles and new interactions. Among these new interactions a central role to get an experimental signal of a new physics is played by the new neutral gauge bosons, A H and Z H. We study the associated production of general new neutral gauge boson Z¢ and a hard photon in the process e+ + e- <FONT FACE=Symbol>® m</FONT> + + µ- + gamma. For M AH < <FONT FACE=Symbol>Ö</FONT>S we show that the hard photon energy distribution in e+ + e- <FONT FACE=Symbol>® g</FONT> + f + f can present a model dependence and establish the theoretical origin of a new possible heavy neutral gauge boson.