Kinematical cusp and resonance interpretations of the X(2900)

We examine whether the LHCb vector udc over bar s over bar state X(2900) can be interpreted as a kinematical cusp effect arising from (D) over bar *K* and (D-1) over barK(*) interactions. The production amplitude is modelled as a triangle diagram with hadronic final state interactions. A satisfactory fit to the Dalitz plot projection is obtained that leverages the singularities of the production diagram without the need for D over bar K resonances. A somewhat better fit is obtained if the final state interactions are strong enough to generate resonances, although the evidence in favour of this scenario is not conclusive. (C) 2020 The Authors. Published by Elsevier B.V.

Automated summary

This study investigates the interpretation of the LHCb vector udc over bar s over bar state X(2900) as a kinematical cusp effect from (D)*K* and (D-1)*K(*) interactions. A satisfactory fit to the Dalitz plot projection is achieved using a triangle diagram model with hadronic final state interactions. The evidence for the generation of resonances due to strong enough final state interactions is inconclusive, but provides a somewhat better fit.