text:   the LIGO and Virgo O1-O3a Observing Runs",1,['New paper led by Javier!\n\n<LINK>\n\nWe found no evidence for binary black holes with spins that are anti-aligned with the orbit in the current BBH population. This suggests that BBHs cannot be formed solely through dynamical capture in dense stellar environments. <LINK>'],21,05,266