  We present cosmological parameter measurements from the publicly available
Baryon Oscillation Spectroscopic Survey (BOSS) data on anisotropic galaxy
clustering in Fourier space. Compared to previous studies, our analysis has two
main novel features. First, we use a complete perturbation theory model that
properly takes into account the non-linear effects of dark matter clustering,
short-scale physics, galaxy bias, redshift-space distortions, and large-scale
bulk flows. Second, we employ a Markov-Chain Monte-Carlo technique and
consistently reevaluate the full power spectrum likelihood as we scan over
different cosmologies. Our baseline analysis assumes minimal $\Lambda$CDM,
varies the neutrino masses within a reasonably tight range, fixes the
primordial power spectrum tilt, and uses the big bang nucleosynthesis prior on
the physical baryon density $\omega_b$. In this setup, we find the following
late-Universe parameters: Hubble constant $H_0=(67.9\pm 1.1)$
km$\,$s$^{-1}$Mpc$^{-1}$, matter density fraction $\Omega_m=0.295\pm 0.010$,
and the mass fluctuation amplitude $\sigma_8=0.721\pm 0.043$. These parameters
were measured directly from the BOSS data and independently of the Planck
cosmic microwave background observations. Scanning over the power spectrum tilt
or relaxing the other priors do not significantly alter our main conclusions.
Finally, we discuss the information content of the BOSS power spectrum and show
that it is dominated by the location of the baryon acoustic oscillations and
the power spectrum shape. We argue that the contribution of the
Alcock-Paczynski effect is marginal in $\Lambda$CDM, but becomes important for
non-minimal cosmological models.
