  We use time-sliced perturbation theory (TSPT) to give an accurate description
of the infrared non-linear effects affecting the baryonic acoustic oscillations
(BAO) present in the distribution of matter at very large scales. In TSPT this
can be done via a systematic resummation that has a simple diagrammatic
representation and does not involve uncontrollable approximations. We discuss
the power counting rules and derive explicit expressions for the resummed
matter power spectrum up to next-to leading order and the bispectrum at the
leading order. The two-point correlation function agrees well with N-body data
at BAO scales. The systematic approach also allows to reliably assess the shift
of the baryon acoustic peak due to non-linear effects.
