Search for a doubly charged DDK bound state in Upsilon(1S, 2S) inclusive decays and via direct production in e(+)e(-) collisions at root s=10.520, 10.580, and 10.867 GeV
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 root 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 Upsilon(1S) and Upsilon(2S) inclusive decays (B(Upsilon(1S, 2S) -4 R++ + anything) x B(R++ -> D+D-s*(+))), the product values of Born cross section and branching fraction in e(+)e(-) collisions (sigma(e(+)e(-) -> R++ + anything) x B(R++ -> D+D-s*(+))) at root 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.