## Little Higgs models and electroweak measurements

Using effective field theory approach, we study the constraints from electroweak data on the SU(5)/SO(5), SU(6)/SP(6), SU(3)xU(1) little Higgs models and their variations. We construct an effective theory valid above the electroweak symmetry breaking scale in these models that includes dimension-six operators induced by integrating out heavy fields. We calculate the constraints on the models using the results of [Z. Han and W. Skiba, Phys. Rev. D 71, 075009 (2005)], where bounds on arbitrary linear combinations of flavor and CP conserving dimension-six operators are given. We present the constraints in terms of the bounds on the masses of heavy fermionsmore »