Observation of $\overline{B} \to D^{(*)} \pi^+\pi^- \ell^-\overline{\nu}$ decays in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance

J. P. Lees; V. Poireau; V. Tisserand; N. Arnaud; M. Davier; D. Derkach; G. Grosdidier; F. Le Diberder; A. M. Lutz; B. Malaescu; P. Roudeau; A. Stocchi; G. Wormser

Observation of $\overline{B} \to D^{(*)} \pi^+\pi^- \ell^-\overline{\nu}$ decays in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance

J. P. Lees ¹ V. Poireau ¹ V. Tisserand ¹ N. Arnaud ² M. Davier ² D. Derkach ² G. Grosdidier ² F. Le Diberder ² A. M. Lutz ² B. Malaescu ² P. Roudeau ² A. Stocchi ² G. Wormser ²

1 LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules - Laboratoire d'Annecy de Physique des Particules

2 LAL - Laboratoire de l'Accélérateur Linéaire

Abstract : We report on measurements of the decays of $\overline{B}$ mesons into the semileptonic final states $\overline{B} \to D^{(*)} \pi^+\pi^- \ell^-\overline{\nu}$, where $D^{(*)}$ represents a $D$ or $D^*$ meson and $\ell^-$ is an electron or a muon. These measurements are based on $471\times 10^6$ $B\overline{B}$ pairs recorded with the $BABAR$ detector at the SLAC asymmetric $B$ Factory PEP-II. We determine the branching fraction ratios $R^{(*)}_{\pi^+\pi^-} = \mathcal{B}(\overline{B} \to D^{(*)} \pi^+\pi^- \ell^- \overline{\nu})/\mathcal{B}(\overline{B} \to D^{(*)} \ell^-\overline{\nu})$ using events in which the second $B$ meson is fully reconstructed. We find $R_{\pi^+\pi^-} = 0.067 \pm 0.010 \pm 0.008$ and $R^*_{\pi^+\pi^-} = 0.019 \pm 0.005 \pm 0.004$, where the first uncertainty is statistical and the second is systematic. Based on these results, we estimate that $\overline{B} \to D^{(*)}\pi\pi\ell^-\overline{\nu}$ decays, where $\pi$ denotes both a $\pi^\pm$ and $\pi^0$ meson, account for up to half the difference between the measured inclusive semileptonic branching fraction to charm hadrons and the corresponding sum of previously measured exclusive branching fractions.

Document type :

Journal articles

Domain :

Physics [physics] / High Energy Physics - Experiment [hep-ex]

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http://hal.in2p3.fr/in2p3-01182326
Contributor : Sabine Starita <>
Submitted on : Friday, July 31, 2015 - 10:14:57 AM
Last modification on : Thursday, January 11, 2018 - 6:14:21 AM

Observation of $\overline{B} \to D^{(*)} \pi^+\pi^- \ell^-\overline{\nu}$ decays in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance

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Observation of $\overline{B} \to D^{(*)} \pi^+\pi^- \ell^-\overline{\nu}$ decays in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance

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