  The angular correlation function of the background shear-foreground galaxy
distribution probes the three dimensional cross power spectrum between mass and
galaxies. The same cross power spectrum is also probed when foreground galaxy
distribution is cross-correlated with a distribution of background sources
disjoint in redshift space. The kernels that project three dimensional
clustering to the two dimensional angular space is different for these two
probes. When combined, they allow a study of the galaxy-mass cross power
spectrum from linear to non-linear scales. By inverting the background
shear-foreground galaxy correlation function measured by the Sloan Digital Sky
Survey, we present a first estimate of the cross power spectrum between mass
and galaxies at low redshifts.
