PNNL

Abstract

We report the results of a first search for a doubly-charged DDK bound state, denoted the R^{++}, in \Upsilon(1S) and \Upsilon(2S) inclusive decays and via direct production in e^+e^- collisions at \sqrt{s} = 10.520, 10.580, and 10.867 GeV. The search uses data accumulated with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. No significant signals are observed in the D^{+}D_{s}^{*+} invariant-mass spectra of all studied modes. The 90\% credibility level upper limits on their product branching fractions in \Upsilon(1S) and \Upsilon(2S) inclusive decays ({\cal B}(\Upsilon(1S,2S) \to R^{++} + anything) \times {\cal B}(R^{++} \to D^{+} D_{s}^{*+})), and the product values of Born cross section and branching fraction in e^+e^- collisions (\sigma(e^+e^- \to R^{++} + anything) \times {\cal B}(R^{++} \to D^{+} D_{s}^{*+})) at \sqrt{s} = 10.520, 10.580, and 10.867 GeV under different assumptions of R^{++} masses varying from 4.13 to 4.17 GeV/c^2, and widths varying from 0 to 5 MeV are obtained.