$$X_1(2900)$$ as a $$\bar{D}_1 K$$ molecule

The analyses of the LHCb data on X(2900) in the $$D^- K^+$$ D - K + spectrum are performed. Both dynamically generated and explicitly introduced $$X_1(2900)$$ X 1 ( 2900 ) are considered. The results show that both these two approaches support the interpretation of $$X_1(2900)$$ X 1 ( 2900 ) as a $$\bar{D}_1 K$$ D ¯ 1 K molecular state, with $$J^{P}=1^-$$ J P = 1 - and an iso-singlet interpretation is much more favorable. The effect of triangle singularity on the production of $$X_1(2900)$$ X 1 ( 2900 ) is also discussed, and it is found that it cannot be interpreted as a pure triangle cusp.