Related papers: A new sum rule to determine Vub/Vcb
A precise determination of |V_{ub}| can be obtained exploiting the sum rule for inclusive charmless semileptonic B-meson decays. The sum rule is derived on the basis of light-cone expansion and b-flavored quantum number conservation. The…
We briefly review the recent progress in the exclusive determination of |V(ub)| using QCD sum rules on the light cone.
Current methods of determining V_ub are dominated by theoretical uncertainties. We present Monte Carlo simulations of three promising methods of determining V_ub with small theoretical and experimental errors. We find that with data samples…
The sum rule for charmless inclusive semileptonic B-meson decays allows a theoretically clean and experimentally efficient determination of |V_{ub}|. The leading twist contribution to the sum rule is known in QCD. We compute higher twist…
The precise determination of the CKM elements $V_{cb}$ and $V_{ub}$ is crucial for any new physics analysis in the flavour sector. Their values can be determined from several tree-level decays: $V_{cb}$ can be extracted from $B\to D\ell\nu$…
We update the full set of $\bar{B}_s\rightarrow K$ form factors using light-cone sum rules with an on-shell kaon. Our approach determines the relevant sum rule parameters -- the duality thresholds -- from a Bayesian fit for the first time.…
A sum rule for determining |V_us| from a combination of hadronic tau decay and electroproduction data is discussed. Indications of problems with analogous, purely tau-decay-based analyses, most likely associated with slow convergence of the…
We present a model independent closed form expression for |V_{ub}|^2/|V_{tb} V_{ts}^*|^2, which includes the resummation of large endpoint logarithms as well as the interference effects from the operators $O_2$ and $O_8$. We demonstrate…
The angles of the CKM unitarity triangle are now known well enough to allow a determination of its sides from global fits, with good accuracy. Assuming that new physics does not affect the angles, UTfit and CKMfitter find $|V_{ub}| =…
In order to determine the ratio of CKM matrix elements |V_{ub}/V_{cb}| (and |V_{ub}|), we propose a new model-independent method based on the heavy quark effective theory, which is theoretically described by the phase space factor and the…
The zero recoil limit of the B -> D l nu form factors is calculated on the lattice, which provides a model-independent determination of |Vcb|. Considering a ratio of form factors, in which the bulk of statistical and systematic errors…
The last two years have seen an impressive improvement in the determination of $|V_{ub}|$, especially from inclusive decays. The error on $|V_{ub}|$ measured with inclusive decays was reduced from 18% (PDG 2004) to 8% (PDG 2006). This…
We propose a new model-independent method, to determine the ratio $|V_{ub}/V_{cb}|$, which is theoretically described by the phase space factor and the well-known perturbative QCD correction only. We explore the possible experimental…
The $b \to c$ semileptonic sum rules provide relations between the decay rates of $B \to D^{(*)} \tau\bar\nu$ and $\Lambda_b \to \Lambda_c \tau\bar\nu$. Starting from the heavy quark and zero-recoil limits, we revisit the derivation of the…
We explore the theoretical feasibility of extracting V_ub from two ratios built from B meson inclusive partial decays, R_1 = Gamma(b-> u cbar s)/3Gamma(b -> c l nu), and R_2 = [Gamma(b -> c X) - Gamma(b -> cbar X)]/Gamma(b -> c ubar d). We…
We update the extraction of |V_{us}| from hadronic tau decay data in light of recent BaBar and Belle results on the branching fractions of a number of important strange decay modes. A range of sum rule analyses is performed, particular…
We derive a new QCD sum rule for $D(0^+)$ which has only the $D\pi$ continuum with a resonance in the hadron side, using the assumption similar to that has been successfully used in our previous work to the mass of $D_s(0^+)(2317)$. For the…
We present an updated determination of the values of $\vert V_{cb} \vert$, $R(D^*)$ and $\vert V_{ub} \vert/\vert V_{cb} \vert$ based on the new data on semileptonic $B \to D^* \ell \nu_\ell$ decays by the Belle and Belle-II Collaborations…
Recent progress in determination of $|V_{cb}|$ within the heavy quark expansion is reported. Both exclusive and inclusive approaches are discussed.
A new method to extract $|V_{\rm bc}|$ is proposed based on a sum--rule for semileptonic decays of the $B$ meson. The method relies on much weaker assumptions than previous approaches which are based on heavy--quark symmetry. This sum--rule…