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Measurement of the B0→ X-u ℓ+νℓ decays near the kinematic endpoint of the lepton spectrum and search for violation of isospin symmetry

  • Author(s): Aubert, B
  • Bona, M
  • Boutigny, D
  • Karyotakis, Y
  • Lees, JP
  • Poireau, V
  • Prudent, X
  • Tisserand, V
  • Zghiche, A
  • Garra Tico, J
  • Grauges, E
  • Lopez, L
  • Palano, A
  • Pappagallo, M
  • Eigen, G
  • Stugu, B
  • Sun, L
  • Abrams, GS
  • Battaglia, M
  • Brown, DN
  • Button-Shafer, J
  • Cahn, RN
  • Groysman, Y
  • Jacobsen, RG
  • Kadyk, JA
  • Kerth, LT
  • Kolomensky, YG
  • Kukartsev, G
  • Lopes Pegna, D
  • Lynch, G
  • Mir, LM
  • Orimoto, TJ
  • Osipenkov, IL
  • Ronan, MT
  • Tackmann, K
  • Tanabe, T
  • Wenzel, WA
  • Del Amo Sanchez, P
  • Hawkes, CM
  • Watson, AT
  • Koch, H
  • Schroeder, T
  • Walker, D
  • Asgeirsson, DJ
  • Cuhadar-Donszelmann, T
  • Fulsom, BG
  • Hearty, C
  • Mattison, TS
  • McKenna, JA
  • Khan, A
  • Saleem, M
  • Teodorescu, L
  • Blinov, VE
  • Bukin, AD
  • Druzhinin, VP
  • Golubev, VB
  • Onuchin, AP
  • Serednyakov, SI
  • Skovpen, YI
  • Solodov, EP
  • Todyshev, KY
  • Bondioli, M
  • Curry, S
  • Eschrich, I
  • Kirkby, D
  • Lankford, AJ
  • Lund, P
  • Mandelkern, M
  • Martin, EC
  • Stoker, DP
  • Abachi, S
  • Buchanan, C
  • Foulkes, SD
  • Gary, JW
  • Liu, F
  • Long, O
  • Shen, BC
  • Vitug, GM
  • Zhang, L
  • Paar, HP
  • Rahatlou, S
  • Sharma, V
  • Berryhill, JW
  • Campagnari, C
  • Cunha, A
  • Dahmes, B
  • Hong, TM
  • Kovalskyi, D
  • Richman, JD
  • Beck, TW
  • Eisner, AM
  • Flacco, CJ
  • Heusch, CA
  • Kroseberg, J
  • Lockman, WS
  • Schalk, T
  • Schumm, BA
  • Seiden, A
  • Wilso, MG
  • Winstrom, LO
  • et al.
Creative Commons 'BY' version 4.0 license
Abstract

We present the first measurement of the B0 → X-u ℓ+νℓ partial branching fraction in the endpoint region of the lepton momentum spectrum, above the threshold for B → Xcℓνℓ decays. The analysis is based on a sample of 383 million γ(4S) decays into BB pairs collected with the BABAR detector at the PEP-II e+e- storage rings. We select B0B0 events by partially reconstructing one B meson via the B0 → Dz.ast;+ℓ- ̄νℓ decays then select B0 → X- u ℓ+νℓ decays identifying a second high momentum lepton. In the momentum interval ranging from 2.3 to 2.6 GeV/c we measure the partial branching fraction πB(B0 → Xuℓν) = (1.30 ± 0.21stat ± 0.07syst) × 10-4 where the first error is statistical and the second is systematic. By comparing this measurement with the one obtained from untagged B decays we obtain R+/0 = ΔB(B0 → Xuℓν)/ ΔB(B+ → Xuℓν) = 1.18 ± 0.35stat ± 0.17syst. Using this measurement we extract a limit on the contributions from processes breaking isospin symmetry in charmless semileptonic B decays.

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