What theoretical framework predicts the expected ratio of normal matter (baryons) in a galaxy like the Milky Way?

Answer

Cosmological models built on the physics of the Big Bang

The expected quantity of baryonic matter is determined by models describing the early universe, specifically those derived from Big Bang physics, which dictate the initial creation ratio of hydrogen and helium.

What theoretical framework predicts the expected ratio of normal matter (baryons) in a galaxy like the Milky Way?
galaxyAstronomerdark mattermassMilky Way