X_1(2900) as a D_1 K molecule

TL;DR

The paper investigates the nature of X(2900) in the D^- K^+ spectrum, supporting its interpretation as a D_1 K molecular state with J^{P}=1^- and favoring an iso-singlet configuration, while discussing triangle singularity effects.

Contribution

It provides a combined analysis of dynamically generated and explicit models, supporting the molecular interpretation of X(2900) and clarifying the role of triangle singularities.

Findings

X(2900) is consistent with a D_1 K molecular state

Iso-singlet interpretation is more favorable

Triangle singularity does not explain X(2900) as a pure cusp

Abstract

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