  We study the disk-jet connection in supermassive black holes by investigating
the properties of their optical and radio emissions utilizing the SDSS-DR7 and
the NVSS catalogs. Our sample contains 7017 radio-loud quasars with detection
both at 1.4~GHz and SDSS optical spectrum. Using this radio-loud quasar sample,
we investigate the correlation among the jet power ($P_{\rm jet}$), the
bolometric disk luminosity ($L_{\rm disk}$), and the black hole mass ($M_{\rm
BH}$) in the standard accretion disk regime. We find that the jet powers
correlate with the bolometric disk luminosities as $\log P_{\rm jet} =
(0.96\pm0.012)\log L_{\rm disk} + (0.79 \pm 0.55)$. This suggests that the jet
production efficiency of $\eta_{\rm jet}\simeq1.1_{-0.76}^{+2.6}\times10^{-2}$
assuming the disk radiative efficiency of $0.1$ implying low black hole spin
parameters and/or low magnetic flux for radio-loud quasars. But it can be also
due to dependence of the efficiency on geometrical thickness of the accretion
flow which is expected to be small for quasars accreting at the disk Eddington
ratios $0.01 \lesssim \lambda \lesssim 0.3$. This low jet production efficiency
does not significantly increase even if we set the disk radiative efficiency of
0.3. We also investigate the fundamental plane in our samples among $P_{\rm
jet}$, $L_{\rm disk}$, and $M_{\rm BH}$. We could not find a statistically
significant fundamental plane for radio-loud quasars in the standard accretion
regime.
