Search for a doubly charged DDK bound state in ϒ (1S, 2S) inclusive decays and via direct production in e+e- collisions at s =10.520, 10.580, and 10.867 GeV

We report the results of a first search for a doubly charged DDK bound state, denoted the R++, in ϒ(1S) and ϒ(2S) inclusive decays and via direct production in e+e- collisions at 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+Ds∗+ invariant-mass spectra of all studied modes. The 90% credibility level upper limits on their product branching fractions in ϒ(1S) and ϒ(2S) inclusive decays (B(ϒ(1S, 2S)→R+++anything)×B(R++→D+Ds∗+)), the product values of Born cross section and branching fraction in e+e- collisions (σ(e+e-→R+++anything)×B(R++→D+Ds∗+)) at s=10.520, 10.580, and 10.867 GeV under different assumptions of R++ masses varying from 4.13 to 4.17 GeV/c2 and widths varying from 0 to 5 MeV are obtained.