Observation of the Semileptonic Decay ${D}^{0}\ensuremath{\rightarrow}{a}_{0}(980{)}^{\ensuremath{-}}{e}^{+}{\ensuremath{\nu}}_{e}$ and Evidence for ${D}^{+}\ensuremath{\rightarrow}{a}_{0}(980{)}^{0}{e}^{+}{\ensuremath{\nu}}_{e}$

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Observation of the Semileptonic Decay $D^{0} \to a_{0} (980)^{-} e^{+} ν_{e}$ and Evidence for $D^{+} \to a_{0} (980)^{0} e^{+} ν_{e}$

M. Ablikim et al. (BESIII Collaboration)

Phys. Rev. Lett. 121, 081802 – Published 24 August 2018

Abstract

Using an $e^{+} e^{-}$ collision data sample of $2.93 {fb}^{- 1}$ collected at a center-of-mass energy of 3.773 GeV by the BESIII detector at BEPCII, we report the observation of $D^{0} \to a_{0} (980)^{-} e^{+} ν_{e}$ and evidence for $D^{+} \to a_{0} (980)^{0} e^{+} ν_{e}$ with significances of $6.4 σ$ and $2.9 σ$ , respectively. The absolute branching fractions are determined to be $B (D^{0} \to a_{0} (980)^{-} e^{+} ν_{e}) \times B (a_{0} (980)^{-} \to η π^{-}) = [1.3 3_{- 0.29}^{+ 0.33} (stat) \pm 0.09 (syst)] \times 10^{- 4}$ and $B (D^{+} \to a_{0} (980)^{0} e^{+} ν_{e}) \times B (a_{0} (980)^{0} \to η π^{0}) = [1.6 6_{- 0.66}^{+ 0.81} (stat) \pm 0.11 (syst)] \times 10^{- 4}$ . This is the first time the $a_{0} (980)$ meson has been measured in a $D^{0}$ semileptonic decay, which would open one more interesting page in the investigation of the nature of the puzzling $a_{0} (980)$ states.

Received 12 March 2018
Revised 20 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.081802

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Published by the American Physical Society