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

TL;DR

This paper reports the first measurement of inclusive $D^{* extpm}$ production in $
S$ decays, revealing an excess over the expected rate from virtual photon annihilation, using data from the BaBar detector.

Contribution

It provides the first measurement of the branching fraction and momentum distribution of $D^{* extpm}$ in $
S$ decays, indicating additional production mechanisms beyond virtual photon processes.

Findings

Branching fraction $r[
S o D^{* extpm} X] = (2.52 \pm 0.13 ext{(stat)} \pm 0.15 ext{(syst)}) imes 10^{-2}$

Evidence for excess $D^{* extpm}$ production over expected virtual photon annihilation rate

Measured $D^{* extpm}$ momentum distribution in $
S$ rest frame

Abstract

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