Observation of inclusive $D^{*\pm}$ production in the decay of $Υ(1S)$

Abstract

We present a study of the inclusive $D^{*\pm}$ production in the decay of $Υ(1S)$ using $(98.6 \pm 0.9)\times 10^6$ $Υ(2S)$ mesons collected with the BaBar detector at the $Υ(2S)$ resonance. Using the decay chain $Υ(2S)\to π^+ π^- Υ(1S), Υ(1S) \to D^{*\pm} X$, where X is unobserved, we measure the branching fraction $\BR[Υ(1S)\to D^{*\pm} X] = (2.52 \pm 0.13({\rm stat}) \pm 0.15({\rm syst}))%$ and the $D^{*\pm}$ momentum distribution in the rest frame of the $Υ(1S)$. We find evidence for an excess of $D^{*\pm}$ production over the expected rate from the virtual photon annihilation process $Υ(1S)\toγ^*\to c\bar c\to D^{*\pm} X$.