Invariant-mass distribution of cc-bar in Upsilon(1S) -> cc-bar + X

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We calculate the invariant-mass distribution for the cc-bar pair produced in the inclusive Upsilon(1S) decay based on the color-singlet mechanism of the nonrelativistic quantum chromodynamics factorization approach at leading order in the bottom-quark velocity vb in the meson rest frame. As the short-distance processes, we consider bb-bar -> g*gg followed by g* -> cc-bar and bb-bar -> gamma* -> cc-bar at leading order in the strong coupling. The invariant-mass distribution of the bb-bar -> cc-bar gg contribution has a sharp peak just above the threshold and that of the bb-bar -> gamma* -> cc-bar channel is concentrated at the maximally allowed kinematic end point. We predict that Gamma[Upsilon(1S) -> cc-bar+X]/Gamma[Upsilon(1S)->light hadrons] = 0.065 alphaₛ, which is smaller than a previous result by about 20%.