Testing General Relativity with Growth rate measurement from Sloan
  Digital Sky Survey III Baryon Oscillations Spectroscopic Survey galaxies
  The measured redshift ($z$) of an astronomical object is a combination of
Hubble recession, gravitational redshift and peculiar velocity. The line of
sight distance to a galaxy inferred from redshift is affected by the peculiar
velocity component of galaxy redshift, which is observed as an anisotropy in
the correlation function. This anisotropy allows us to measure the linear
growth rate of matter ($f\sigma_8$). We measure the $f\sigma_8$ at $z=0.57$
using the CMASS sample from Data Release 11 of Sloan Digital Sky Survey III
(SDSS III) Baryon Oscillations Spectroscopic Survey (BOSS). The galaxy sample
consists of 690,826 massive galaxies in the redshift range 0.43-0.7 covering
8498 deg$^2$. Here we report the first simultaneous measurement of $f\sigma_8$
and background cosmological parameters using Convolution Lagrangian
Perturbation Theory (CLPT) with Gaussian streaming model (GSRSD). We arrive at
a constraint of $f\sigma_8=0.462\pm0.041$ (9\% accuracy) at effective redshift
($\bar{z}=0.57$) when we include Planck CMB likelihood while marginalizing over
all other cosmological parameters. We also measure $b\sigma_8=1.19\pm0.03$,
$H(z=0.57)=89.2\pm3.6$ km s$^{-1}$ Mpc$^{-1}$ and $D_A(z=0.57)=1401\pm23$ Mpc.
Our analysis also improves the constraint on $\Omega_c h^2=0.1196\pm0.0009$ by
a factor of 3 when compared to the Planck only measurement($\Omega_c h^2=0.1196
\pm 0.0031$). Our results are consistent with Planck $\Lambda$CDM-GR prediction
and all other CMASS measurements, even though our theoretical models are fairly
different. This consistency suggests that measurement of $f\sigma_8$ from
Redshift space distortions at multiple redshifts will be a sensitive probe of
the theory of gravity that is largely model independent, allowing us to place
model-independent constraints on alternative models of gravity.
