  We consider one of the most significant deviations from the Standard Model:
the forward-backward asymmetry of the b-quark measured at leptonic colliders.
We investigate the possibility to solve this discrepancy by introducing new
physics at the TeV scale. We focus on models where the Higgs is a pseudo
Nambu-Goldstone boson of a new strongly coupled sector with a global SO(5)
symmetry broken spontaneously to SO(4). Besides the usual top partners, we
introduce bottom partners in the representations 16 and 4 of SO(5) and show
that they can improve significantly the fit by correcting the Zbb couplings. We
also estimate the corrections to the couplings at one-loop and obtain that the
tree-level ones dominate and can give a reliable estimation. We find that the
large shift required for Zb_Rb_R leads to light custodians associated to the
b-quark, similar to the top partners, as well as a rich phenomenology involving
neutral interactions in the bottom-sector.
