  Extended QCD (XQCD) proposed by Kaplan [1] is an interesting reformulation of
QCD with additional bosonic auxiliary fields. While its partition function is
kept exactly the same as that of original QCD, XQCD naturally contains
properties of low energy hadronic models. We analyze the renormalization group
flow of two-dimensional (X)QCD, which is solvable in the limit of large number
of colors Nc, to understand what kind of roles the auxiliary degrees of freedom
play and how the hadronic picture emerges in the low energy region.
