The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic
  Survey DR16 luminous red galaxy and emission line galaxy samples: cosmic
  distance and structure growth measurements using multiple tracers in
  configuration space
  We perform a multi-tracer analysis using the complete Sloan Digital Sky
Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS)
DR16 luminous red galaxy (LRG) and the DR16 emission line galaxy (ELG) samples
in the configuration space, and successfully detect a cross correlation between
the two samples, and find the growth rate to be $f\sigma_8=0.342 \pm 0.085$
($\sim25$ per cent accuracy) from the cross sample alone. We perform a joint
measurement of the baryonic acoustic oscillation (BAO) and redshift space
distortion (RSD) parameters at a single effective redshift of $z_{\rm eff}=
0.77$, using the auto- and cross-correlation functions of the LRG and ELG
samples, and find that the comoving angular diameter distance $D_M(z_{\rm
eff})/r_d = 18.85\pm 0.38$, the Hubble distance $D_H(z_{\rm eff})/r_d = 19.64
\pm 0.57$, and $f\sigma_8(z_{\rm eff}) = 0.432 \pm 0.038$, which is consistent
with a $\Lambda$CDM model at $68\%$ CL. Compared to the single-tracer analysis
on the LRG sample, the Figure of Merit (FoM) of $\alpha_{\perp}, \alpha_{||}$
and $f\sigma_8$ is improved by a factor of $1.11$ in our multi-tracer analysis,
and in particular, the statistical uncertainty of $f\sigma_8$ is reduced by
$11.6 \%$.
