  We study the nonlinear evolution of the baryon acoustic oscillations (BAO) in
the dark matter power spectrum and correlation function using renormalized
perturbation theory (RPT). In a previous paper we showed that RPT successfully
predicts the damping of acoustic oscillations; here we extend our calculation
to the enhancement of power due to mode-coupling. We show that mode-coupling
generates additional oscillations that are out of phase with those in the
linear spectrum, leading to shifts in the scales of oscillation nodes defined
with respect to a smooth spectrum. When Fourier transformed, these out of phase
oscillations induce percent-level shifts in the acoustic peak of the two-point
correlation function. We present predictions for these shifts as a function of
redshift; these should be considered as a robust lower limit to the more
realistic case that includes in addition redshift distortions and galaxy bias.
We show that these nonlinear effects occur at very large scales, leading to a
breakdown of linear theory at scales much larger than commonly thought. We
discuss why virialized halo profiles are not responsible for these effects,
which can be understood from basic physics of gravitational instability. Our
results are in excellent agreement with numerical simulations, and can be used
as a starting point for modeling BAO in future observations. To meet this end,
we suggest a simple physically motivated model to correct for the shifts caused
by mode-coupling.
