D1(2420) and its interactions with a kaon: Open charm states with strangeness

In this work we present an attempt to describe the X1(2900) found by the LHCb collaboration, in the experimental data on the invariant mass spectrum of D-K+, as a three-meson molecular state of the KpD over line system. We discuss that the interactions in all the subsystems are attractive in nature, with the pD over line interaction generating over line D1(2420) and the Kp resonating as K1(1270). We find that the system can form a three-body state but with a mass higher than that of X1(2900). We investigate the KpD system too, finding that the three-body dynamics generates an isoscalar state, which can be related to D*s1(2860), and an exotic isovector state. This latter state has a mass similar to that of the X0(2900) and X1(2900) states found by LHCb, but a very small width (similar to 7.4 +/- 0.9 MeV) and necessarily requires more than two quarks to describe its properties. We hope that our findings will encourage experimental investigations of the isovector KpD state. Finally, in the pursuit of finding a description for X1(2900), we study the K over line K*D* system where over line K*D* forms 0+, 1+, and 2+ states. We do not find a state that can be associated with X1(2900).

Automated summary

In this study, we attempt to describe the X1(2900) as a three-meson molecular state of the KpD system in the invariant mass spectrum of D-K+ observed by the LHCb collaboration. The attractive interactions in all subsystems generate the D1(2420) and the K1(1270) resonating as Kp. We find that the system can form a three-body state but with a higher mass than X1(2900). We also investigate the KpD system, discovering an isoscalar state related to D*s1(2860) and an exotic isovector state with a mass similar to X0(2900) and X1(2900) but a very small width, which requires more than two quarks to describe its properties. Our findings hope to encourage experimental investigations of the isovector KpD state. Finally, in the search for a description of X1(2900), we study the K over line K*D* system and do not find a state associated with it.