The \(Z_{cs}(3985)\) as a threshold effect from the \(\bar D_s^ D + \bar D_s D^\) interaction

• Published in: arXiv.org
• Main Authors: Ikeno, Natsumi, Molina, Raquel, Oset, Eulogio
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 08.02.2021
• Subjects: Channels
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2011.13425

We study the \(e^+ e^- \to K^+ ( D_s^{*-} D^0 + D_s^- D^{*0})\) reaction recently measured at BESIII, from where a new \(Z_{cs}\) state has been reported. We study the interaction of \(\bar D_s D^*\) with the coupled channels \(J/\psi K^-\), \(K^{*-} \eta_c\), \(D_s^- D^{*0}\), \(D_s^{*-} D^0\) by means of an extension to the charm sector of the local hidden gauge approach. We find that the \(D_s^- D^{*0}+ D_s^{*-} D^0\) combination couples to \(J/\psi K^-\) and \(K^{*-} \eta_c\), but the \(D_s^- D^{*0}- D_s^{*-} D^0\) combination does not. The coupled channels help to build up strength in the \(D_s^- D^{*0}+ D_s^{*-} D^0\) diagonal scattering matrix close to threshold and, although the interaction is not strong enough to produce a bound state or resonance, it is sufficient to produce a large accumulation of strength at the \(\bar D_s D^*\) threshold in the \(e^+ e^- \to K^+ ( D_s^{*-} D^0 + D_s^- D^{*0})\) reaction in agreement with experiment.