  Recent studies of different X-ray binaries (XRBs) have shown a clear
correlation between the radio and X-ray emission. We present evidence of a
close relationship found between the radio and X-ray emission at different
epochs for GRS1915+105, using observations from the Ryle Telescope and Rossi
X-ray Timing Explorer satellite. The strongest correlation was found during the
hard state (also known as the `plateau' state), where a steady AU-scale jet is
known to exist. Both the radio and X-ray emission were found to decay from the
start of most plateau states, with the radio emission decaying faster. An
empirical relationship of $S_{\rm{radio}}\propto S_{\rm{X-ray}}^{\xi}$ was then
fitted to data taken only during the plateau state, resulting in a power-law
index of $\xi\sim1.7\pm0.3$, which is significantly higher than in other black
hole XRBs in a similar state. An advection-flow model was then fitted to this
relationship and compared to the universal XRB relationship as described by
Gallo et al. (2003). We conclude that either (I) the accretion disk in this
source is radiatively efficient, even during the continuous outflow of a
compact jet, which could also suggest a universal turn-over from radiatively
inefficient to efficient for all stellar-mass black holes at a critical mass
accretion rate ($\dot{m}_{\rm{c}}\approx10^{18.5}$ g/s); or (II) the X-rays in
the plateau state are dominated by emission from the base of the jet and not
the accretion disk (e.g. via inverse Compton scattering from the outflow).
