  Using the latest data pertaining to \bar u-\bar d asymmetry and the spin
polarization functions, detailed implications of the possible values of the
coupling strength of the singlet Goldstone boson \eta' have been investigated
in the \chiCQM with configuration mixing. Using \Delta u, \Delta_3, \bar u-\bar
d and \bar u/\bar d, the possible ranges of the coupling parameters a, \alpha^2
a, \beta^2 a and \zeta^2 a, representing respectively the probabilities of
fluctuations to pions, K, \eta and \eta^{'}, are found. To further constrain
the coupling strength of \eta', detailed fits have been obtained for spin
polarization functions, quark distribution functions and baryon octet magnetic
moments. The fits clearly establish that a small non-zero value of the coupling
of \eta' is preferred over the higher values of $\eta'$ as well as when
\zeta=0, the latter implying the absence of \eta' from the dynamics of \chiCQM.
Our best fit achieves an overall excellent fit to the data, in particular for
\Delta u, \Delta d, \Delta_8 as well as the magnetic moments \mu_{n},
\mu_{\Sigma^-}, \mu_{\Sigma^+} and \mu_{\Xi^-}. The implications of \eta' on
the gluon polarization have also been investigated.
