Don't miss the forest for the trees: the Lyman alpha forest power spectrum in effective field theory

Understand

We derive an effective field theory (EFT) for cosmological Lyman alpha forest fluctuations valid for the power spectrum at the one-loop order.

• The ``bottom-up'' EFT expansion at the level of the transmitted flux is identical to the line-of-sight dependent bias model first derived by Desjacques et al.
• We confirm this result by a ``top-down'' derivation based on the exponential map of the optical depth field.
• Specifically, we show that the combination of the exponential map and conditions of renormalizability generates the same EFT expansion as the ``bottom-up'' approach.