${\rm Y}$ decay to two-charm quark jets as a Probe of the Color Octet Mechanism

Abstract

We calculate the decay rate of bottomonium to two-charm quark jets ${\rm Y}\to c\bar{c}$ at the tree level and one-loop level including color-singlet and color-octet $b\bar{b}$ annihilations. We find that the short distance coefficient of the color-octet piece is much larger than the color-singlet piece, and that the QCD correction will change the endpoint behavior of the charm quark jet. The color-singlet piece is strongly affected by the one-loop QCD correction. In contrast, the QCD correction to the color-octet piece is weak. Once the experiment can measure the branching ratio and energy distribution of the two-charm quark jets in the ${\rm Y}$ decay, the result can be used to test the color octet mechanism or give a strong constraint on the color-octet matrix elements.

Comments: Accepted for publication in Phys. Rev. D, Appendices added