Measurement of the CKM Matrix Element |V_(cb)| from B⁰ to D^(*-) ell^+ ν_ell at Belle
read the original abstract
We present a new measurement of the CKM matrix element $|V_{cb}|$ from $B^{0} \to D^{*-} \ell^+ \nu_\ell$ decays, reconstructed with the full Belle data set of $711 \, \rm fb^{-1}$ integrated luminosity. Two form factor parameterizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|$ and the decay form factors, where $\mathcal{F}(1)$ is the normalization factor and $\eta_{\rm EW}$ is a small electroweak correction. In the CLN parameterization we find $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}| = (35.06 \pm 0.15 \pm 0.56) \times 10^{-3}$, $\rho^{2}=1.106 \pm 0.031 \pm 0.007$, $R_{1}(1)=1.229 \pm 0.028 \pm 0.009$, $R_{2}(1)=0.852 \pm 0.021 \pm 0.006$. For the BGL parameterization we obtain $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|= (34.93 \pm 0.23 \pm 0.59)\times 10^{-3}$, which is consistent with the World Average when correcting for $\mathcal{F}(1)\eta_{\rm EW}$. The branching fraction of $B^{0} \to D^{*-} \ell^+ \nu_\ell$ is measured to be $\mathcal{B}(B^{0}\rightarrow D^{*-}\ell^{+}\nu_{\ell}) = (4.90 \pm 0.02 \pm 0.16)\%$. We also present a new test of lepton flavor universality violation in semileptonic $B$ decays, $\frac{{\cal B }(B^0 \to D^{*-} e^+ \nu)}{{\cal B }(B^0 \to D^{*-} \mu^+ \nu)} = 1.01 \pm 0.01 \pm 0.03~$. The errors correspond to the statistical and systematic uncertainties respectively. This is the most precise measurement of $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|$ and form factors to date and the first experimental study of the BGL form factor parameterization in an experimental measurement.
This paper has not been read by Pith yet.
Forward citations
Cited by 7 Pith papers
-
$\bar B\to D^{(*)}\ell\bar \nu$ Branching Ratios and Evidence for Isospin Breaking in $\Upsilon(4S)$ Decays
A combined fit to B to D(*) l nu data yields R^{±0}=1.062(19) as evidence for isospin violation in Υ(4S) decays and branching fractions up to 1.6σ larger than prior averages, addressing inconsistencies in V_cb extractions.
-
New physics searches via angular distributions of $ \bar{B} \to D^* (\to D \pi) \tau (\to \ell \nu_\tau \bar{\nu}_\ell) \bar{\nu}_\tau$ decays
Introduces a reconstructible angular distribution for B to D* tau nu decays via tau to lepton chain to extract new physics parameters, projecting 5-6% sensitivities from simulation and lattice form factors.
-
Lepton Flavor Universality tests through angular observables of $\overline{B}\to D^{(\ast)}\ell\overline{\nu}$ decay modes
Angular observables in B→D(*)ℓν decays can distinguish Lorentz structures of new physics contributions fitted to measured R(D(*)) ratios, even when those ratios agree with the Standard Model.
-
Closing the knowledge gap in semileptonic $B\rightarrow X_c\ell\nu$ decays
The unmeasured fraction of inclusive semileptonic B to charm decays is dominated by final states without D mesons, likely from baryons and Ds mesons.
-
Lepton flavour universality in charged-current $B$ decays
LHCb measures R(D*) and R(J/ψ); combined LHCb+Belle data yield 3.1σ tension with SM in R(D) and R(D*).
-
Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2023
The Heavy Flavour Averaging Group reports updated world averages for b-hadron, c-hadron, and tau-lepton properties including branching fractions, lifetimes, mixing, CP violation, and CKM elements.
-
FLAG Review 2024
The FLAG 2024 review provides updated averages of lattice QCD determinations for quark masses, decay constants, form factors, mixing parameters, and nucleon matrix elements.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.