A vector-like heavy quark in the Littlest Higgs model

Abstract

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 $3\times3$ CKM matrix in the Standard Model to a $4\times3$ 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.