A Search for $B^{+}\to {\ell }^{+}{\nu }_{\ell }$ Recoiling Against $B^{-}\to D^0{\ell }^{-}\bar{\nu }X$

Abstract

We present a search for the decay $\B^+ \to \ell^+ ν_{\ell} (\ell = τ, μ, \mathrm{or} e)$ in $(458.9\pm 5.1)\times 10^6$ ${\rm Y}(4S)$ decays recorded with the Babar detector at the SLAC PEP-II $B$-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay ($B^{-}\to D^0{\ell }^{-}\bar{\nu }X$) is selected, and in the recoil a search for $\B^+ \to \ell^+ ν_{\ell}$ signal is performed. The $\tau$ is identified in the following channels: ${\tau }^{+}\to e^{+}{\nu }_e{\overline{\nu }}_{\tau }$, ${\tau }^{+}\to {\mu }^{+}{\nu }_{\mu }{\overline{\nu }}_{\tau }$, ${\tau }^{+}\to {\pi }^{+}{\overline{\nu }}_{\tau }$, and ${\tau }^{+}\to {\pi }^{+}{\pi }^0{\overline{\nu }}_{\tau }$. The analysis strategy and the statistical procedure is set up for the branching fraction extraction or upper limit determination. We determine from the dataset a preliminary measurement of $\mathcal{B}(\B^+ \to τ^+ ν_τ) = (1.8 \pm 0.8 \pm 0.1) \times 10^{-4}$, which excludes zero at $2.4\sigma$, and $f_{B} = 230 \pm 57 \mev $. Combination with the hadronically tagged measurement yields $\mathcal{B}(\B^+ \to τ^+ ν_τ) = (1.8 \pm 0.6) \times 10^{-4}$. We also set preliminary limits on the branching fractions at $\mathcal{B}(\B^+ \to e^+ ν_{e}) < 7.7 \times 10^{-6} (\textrm{90% C.L.})$, $\mathcal{B}(\B^+ \to μ^+ ν_μ) < 11 \times 10^{-6} (\textrm{90% C.L.})$, and $\mathcal{B}(\B^+ \to τ^+ ν_τ) < 3.2 \times 10^{-4} (\textrm{90% C.L.})$.

30 pages, 15 postscript figures, submitted to CKM2008

References in corpus (1)

• Neutral B Meson Mixing in Unquenched Lattice QCD

Cited by in corpus (56)

• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of summer 2016
• FLAG Review 2019
• FLAG Review 2021
• Flavor-phenomenology of two-Higgs-doublet models with generic Yukawa structure
• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2021
• $B$- and $D$-meson leptonic decay constants from four-flavor lattice QCD
• Implications of lepton flavor universality violations in B decays
• Current status of the Standard Model CKM fit and constraints on $\Delta F=2$ New Physics
• Explaining B->Dτν, B->D*τνand B->τνin a 2HDM of type III
• New physics in the weak interaction of $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Anatomy of New Physics in B-Bbar mixing
• Scalar contributions to $b\to c(u)\tau \nu$ transitions
• Evidence for B- -> tau- nu_tau-bar with a Hadronic Tagging Method Using the Full Data Sample of Belle
• On the anomalous enhancement observed in $B\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$ decays
• Search for the rare decay B_s^0->mu^+mu^-
• Evidence of B-->tau nu decays with hadronic B tags
• Can the differences in the determinations of $V_{ub}$ and $V_{cb}$ be explained by New Physics?
• Tau longitudinal polarization in B -> D tau nu and its role in the search for charged Higgs boson
• Phenomenology of semileptonic B-meson decays with form factors from lattice QCD
• The ${\rm Y}$ and ${{\rm Y}}^{\prime }$ Leptonic Widths, $a_{\mu }^b$ and $m_b$ from full lattice QCD
• A Minimal Flavor Violating 2HDM at the LHC
• A Challenge to Lepton Universality in B Meson Decays
• FLAG Review 2024
• Evidence for B- -> tau- nu_bar with a Semileptonic Tagging Method
• Discussing direct search of dark matter particles in the Minimal Supersymmetric extension of the Standard Model with light neutralinos
• Wave functions and decay constants of $B$ and $D$ mesons in the relativistic potential model
• Precision measurements of $B(D^{+}\to {\mu }^{+}{\nu }_{\mu })$, the pseudoscalar decay constant $f_{D^{+}}$, and the quark mixing matrix element $|V_{\mathrm{cd}}|$
• Constraints on New Scalars from the LHC 125 GeV Higgs Signal
• B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks
• How Constrained is the cMSSM?
• Decay constants of B-mesons from non-perturbative HQET with two light dynamical quarks
• The CKM Parameters
• Rare b hadron decays at the LHC
• Do new data on [B+ -> tau+ nu_tau] decays point to an early discovery of supersymmetry at the LHC?
• Decay Constants and Distribution Amplitudes of B Meson in the Relativistic Potential Model
• Flavor Physics and CP Violation
• Search for $B^{-}\to {\mu }^{-}{\bar{\nu }}_{\mu }$ Decays at the Belle Experiment
• Semileptonic and leptonic $B$ decays, circa 2016
• Analysing parameter space correlations of recent 13 TeV gluino and squark searches in the pMSSM
• Analyzing $b\to u$ transitions in semileptonic ${\bar{B}}_s\to K^{\ast +}(\to K\pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ decays
• Impact of vector new physics couplings on $B_s\to (K,K^{\ast })\tau \nu$ and $B\to \pi \tau \nu$ decays
• Observation of CP violation in $D^0\to K^{-}{\pi }^{+}$ as a smoking gun for New Physics
• Recent Developments on the CKM Matrix
• Angular and polarization observables for Majorana-mediated B decays with effective interactions
• B-Meson Decays into Final States with a tau Lepton
• Charged Higgs contribution to ${\bar{B}}_s\to \varphi {\pi }^0$ and ${\bar{B}}_s\to \varphi {\rho }^0$
• Search at the CERN LHC for a light neutralino of cosmological interest
• Leptonic decays of D_s and B^+ mesons in supersymmetric standard model with R-parity violating interactions
• Constraints on R-parity violating interactions in supersymmetric standard model from leptonic decays of D_s and B^+ mesons
• Rare decays of b hadrons
• Measurement of $B^{+}\to {\tau }^{+}{\nu }_{\tau }$ branching fraction with a hadronic tagging method at Belle II
• Radiative corrections of $O(\alpha )$ to $B^{-}\to V^0{\ell }^{-}{\bar{\nu }}_{\ell }$ decays
• Decay of $B^{\pm }\to {\tau }^{\pm }+$ "missing momentum" and direct measurement of the mixing parameter $U_{\tau N}$
• The Lee-Wick Extension of the Two-Higgs Doublet Model
• Measurement of the Ratio of Partial Branching Fractions of Inclusive $\overline{B}\to X_u\ell \overline{\nu }$ to $\overline{B}\to X_c\ell \overline{\nu }$ and the Ratio of their Spectra with Hadronic Tagging