In this article, we review the theory and the experimental status of inclusive semileptonic B meson decays B -> Xc l nu. Based on these inputs, we present the latest determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V_cb
| and of the b-quark mass m_b, obtained by the Heavy Flavor Averaging Group (HFAG).
We review recent experimental and theoretical developments in inclusive semileptonic B -> Xc l nu decays. In particular, we discuss the determination of |Vcb| and of the heavy quark masses through fits based on the Operator Product Expansion.
A reliable determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ is mandatory for precision flavor physics and for the search for CP violating phases from new, heavy particles. In this article, we review the theory of the determina
tion of $|V_{cb}|$ from inclusive semileptonic $B$ decays. We discuss the available measurements of the semileptonic $B$ branching fraction and other inclusive observables in B decays relevant to the determination of $|V_{cb}|$. Finally, we perform a global fit to extract $|V_{cb}|$ and the $b$-quark mass $m_b$.
This paper describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using the decay $B^0to D^{*-}ell^+ u_ell$. We perform a combined measurement of this quantity and of the form factors $rho^2$, $R_1(1)$, and $R_2(1)$ whic
h fully characterize this decay in the framework of heavy-quark effective theory, based on 140 fb$^{-1}$ of Belle data collected near the $Upsilon(4S)$ resonance. The results, based on about 69,000 reconstructed $B^0to D^{*-}ell^+ u_ell$ decays, are $rho^2=1.293pm 0.045pm 0.029$, $R_1(1)=1.495pm 0.050pm 0.062$, $R_2(1)=0.844pm 0.034pm 0.019$ and $mathcal{F}(1)|V_{cb}|=34.4pm 0.2pm 1.0$. The $B^0to D^{*-}ell^+ u_ell$ branching fraction is found to be $(4.42pm 0.03pm 0.25)%$. For all these numbers, the first error is the statistical and the second is the systematic uncertainty. All results are preliminary.
Using the previous Belle measurement of the inclusive photon energy in $Bto X_sgamma$ decays, we determine the first and second moments of this spectrum for minimum photon energies in the $B$ meson rest frame ranging from 1.8 to 2.3 GeV. Combining th
ese measurements with recent Belle data on the lepton energy and hadronic mass moments in $Bto X_cell u$ decays, we perform fits to theoretical expressions derived in the 1S and kinetic mass schemes and extract the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{cb}$, the $b$-quark mass and other non-perturbative parameters. In the 1S scheme analysis we find $|V_{cb}|=(41.56pm 0.68(mathrm{fit})pm 0.08(tau_B))times 10^{-3}$ and $m_b^mathrm{1S}=(4.723pm 0.055)$ GeV. In the kinetic scheme, we obtain $|V_{cb}|=(41.58pm 0.69(mathrm{fit})pm 0.08(tau_B)pm 0.58(mathrm{th}))times 10^{-3}$ and $m_b^mathrm{kin}=(4.543pm 0.075)$ GeV.
