  The Multi-Phase Transport model (AMPT) is used to investigate the
longitudinal broadening of the transverse momentum two-particle correlator
$C_{2}\left(\Delta\eta,\Delta\varphi\right)$, and its utility to extract the
specific shear viscosity, $\eta/s$, of the quark-gluon plasma formed in
ultra-relativistic heavy ion collisions. The results from these model studies
indicate that the longitudinal broadening of
$C_{2}\left(\Delta\eta,\Delta\varphi\right)$ is sensitive to the magnitude of
$\eta/s$. However, reliable extraction of the longitudinal broadening of the
correlator requires the suppression of possible self-correlations associated
with the definition of the collision centrality.
