The relevant part of the abstract: "we derive a cosmic baryon density of Ωb=0.051" .. "This independent measurement is consistent with values derived from the c

The relevant part of the abstract: "we derive a cosmic baryon density of Ωb=0.051" .. "This independent measurement is consistent with values derived from the cosmic microwave background and from Big Bang nucleosynthesis." So they derive the Ωb independently and get the value compatible to what we already know to calculate using CMB and BBN. https://en.wikipedia.org/wiki/Lambda-CDM_model https://en.wikipedia.org/wiki/Lambda-CDM_model "Calculated values : Baryon density parameter[b] Ωb 0.0486±0.0010[e]"