There is a recent proposal 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 a new physics is played by two new heavy neutral gauge bosons. We have studied the two new neutral currents in the Littlest Higgs model and compared with other extended models. For high energy e+e- colliders we present a clear signature for these two new neutral gauge bosons that can indicate the theoretical origin of these particles. Previous analysis by other authors were done at collider energies equal to the new gauge boson mass M_{A_H}. In this paper we show that asymmetries in fermion antifermion production can display model differences in the case M_{A_H} > sqrt{s}. For M_{A_H} < sqrt{s} we show that the hard photon energy distribution in e+e- --> gamma + f + anti-f can present a model dependence. For higher energies, the hard photon energy distribution can be a clear signature for both new neutral gauge bosons. New bounds for the new neutral gauge boson masses are also presented.
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