A vector-like heavy quark in the littlest Higgs model

The littlest Higgs model contains a new vector-like heavy quark in the up sector. There are two interesting features of its existence. One is that it extends the 3 x 3 CKM matrix in the standard model to a 4 x 3 matrix and the other is that it allows Z-mediated flavor changing neutral currents at tree level in the up sector but not in the down sector. We examine a few of possible windows in which the Z-mediated flavor changing neutral currents in the littlest Higgs model can be tested.