Inclusive Charm Production in Upsilon(nS) Decay

Abstract

Based on the NRQCD factorization formalism, we calculate the inclusive charm production rate in Upsilon(nS) decay at leading order in the strong coupling constant alpha_s and the relative velocity v of the b quark in the quarkonium rest frame. The branching fractions for Upsilon(nS) to charm for n=1, 2, and 3 are all around 7-9%. About 60% of the branching fraction into charm is from annihilation of the color-singlet bb-bar pair into gamma^* -> cc-bar. Most of the remaining branching fraction is from annihilation of the color-singlet bb-bar pair decaying into cc-bar gg. We also compute the momentum distributions of the charm quark and charmed hadrons in the decays. The virtual-photon contribution to the charm quark momentum distribution is concentrated at the end point while the cc-bar gg contribution is broad. The momentum distributions for charmed hadrons are obtained by convolving the charm-quark momentum distribution with charm fragmentation functions. This makes the momentum distributions for charmed hadrons softer than that for the charm quark. This effect is particularly significant in the virtual-photon contribution.

27 pages, 5 figures, minor corrections. version published in Phys. Rev. D

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• Relativistic Correction to J/psi and Upsilon Pair Production
• Exclusive heavy quarkonium + gamma production from e+ e- annihilation into a virtual photon
• Simultaneous production of charmonium and bottomonium mesons at LHC
• Relativistic Corrections to the Exclusive Decays of C-even Bottomonia into S-wave Charmonium Pairs
• QCD and Relativistic $O({\alpha }_s{v}^2)$ Corrections to Hadronic Decays of Spin-Singlet Heavy Quarkonia $h_c,h_b$ and ${\eta }_b$
• ${\rm Y}$ decay to two-charm quark jets as a Probe of the Color Octet Mechanism
• Inclusive chi_bJ(nP) Decays to D0 X
• Observation of inclusive $D^{\ast \pm }$ production in the decay of ${\rm Y}(1S)$
• Relativistic corrections to the semi-inclusive decay of $\mathbf{\psi }$ and $\mathbf{{\rm Y}}$
• Invariant-mass distribution of cc-bar in Upsilon(1S) -> cc-bar + X
• p p -> J/psi+Upsilon+X as a clean probe to the quarkonium production mechanism
• Order-$v^4$ Relativistic Corrections to ${\rm Y}$ Inclusive Decay into a Charm pair
• Exclusive decays of χ_{bJ} and η_b into two charmed mesons