Bounds on the Simplest Little Higgs Model Mass Spectrum Through Z Leptonic Decay

We derive the leptonic neutral current in the simplest little Higgs model and compute the contribution of the model to the decay width Z → e+e−. Using the precision electroweak data we obtain a strong lower bound f ≥ 5.6 TeV at 95% C.L. on the characteristic energy scale of the model. It results in a lower bound for the new gauge bosons W ′± and Z ′ as being MW ′± ≥ 2.6 TeV and MZ′ ≥ 3.1 TeV, respectively. We also present the allowed values of the k = f1/f2 which is the parameter relating the two vacuum expectation values of the scalar triplets in the model, and the μ parameter of a quadratic term, involving the triplets, necessary to provide an acceptable mass range for the standard Higgs boson.