相关论文: |V_{ub}| from B-> pi e nu

The $B_{l4}$ decays offer an independent method for determining the Cabibbo-Kobayashi-Maskawa matrix element $\vert V_{ub} \vert$, with a QCD analysis of the underlying $B \to \pi\pi$ form factors serving as a crucial component. We present…

We present a lattice QCD calculation of the form factors and differential decay rates for semileptonic decays of the heavy-light mesons $B$ and $D$ to the final state $\pi l\nu$. The results are obtained with three methodological…

A new method is suggested to calculate the $B\to \pi\pi$ hadronic matrix elements from QCD light-cone sum rules. To leading order in $\alpha_s$ and $1/m_b$, the sum rule reproduces a factorizable matrix element, in accordance with the…

I discuss QCD sum rules determinations of the form factors governing the decay $B \to \pi (\rho) \ell \nu$. For some of these form factors the computed dependence on the momentum transferred does not agree with the expectation from the…

The determinations of $|V_{\rm ub}|$ from the exclusive branching ratios of $B\to \tau \nu$ and $B \to \pi l \nu$ tend to show a tension at the level of $3\sigma$ \cite{Beringer:1900zz}. On the theoretical side they depend on the lattice…

We have analyzed the $B\to \pi $ and $B_{s}\to K$ semileptonic form factors and $B\to V\gamma (V=K^*,\rho,\omega)$ processes in the light-cone QCD sum rules. In order to enhance the predictivity and reliability of numerical results the…

In this article, we study the $B \to K^*_2(1430)$, $a_2(1320)$, $f_2(1270)$ form-factors with the light-cone QCD sum rules, where the $B$-meson light-cone distribution amplitudes are used. In calculations, we observe that the line-shapes of…

We update the lattice calculation of the $B\to\pi$ semileptonic form factors, which have important applications to the CKM matrix element $|V_{ub}|$ and the $B\to\pi\ell^+\ell^-$ rare decay. We use MILC asqtad ensembles with $N_f=2+1$ sea…

We present an improved calculation of $B\to$ light pseudoscalar formfactors from light-cone sum rules, including one-loop radiative corrections to twist-2 and twist-3 contributions, and leading order twist-4 corrections. The total…

According to heavy-meson chiral perturbation theory, the vector form factor $f_+(q^2)$ of exclusive semi-leptonic decay $B\to \pi \ell \nu$ is closely related, at least in the soft-pion region (i.e., $q^{2} \sim (m_B-m_{\pi})^2$), to the…

In this paper, we calculate the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ by the semileptonic decay $B^+\to \omega\ell^+\nu$. For the transition form factors (TFFs) $A_1(q^2)$, $A_2(q^2)$, and $V(q^2)$ of $B^+\to \omega$, we…

Using a large sample of D0 to K mu nu and pi mu nu decays collected by the FOCUS photoproduction experiment at Fermilab, we present new measurements of the q^2 dependence for the f+(q^2) form factor. These measured f+(q^2) form factors are…

We present a lattice QCD calculation of the $B \rightarrow D l \nu$ semileptonic decay form factors $f_+(q^2)$ and $f_0(q^2)$ for the entire physical $q^2$ range. Non-relativistic QCD (NRQCD) bottom quarks and Highly Improved Staggered…

The behavior of the $\bpi$ form factors in the entire physical range is examined in a model independent way. Unitarity bounds are further constrained by the lattice results (APE). From this analysis, we obtain $f^{+}(0) = 0.38 \pm .03$ if…

We present the first lattice QCD calculation of the form factor for B-> D* l nu with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC configurations), and the Fermilab action…

Electromagnetic form factors of the transition $\pi+\gamma_{virt.}\ra A_1$ are calculated by QCD sum rules technique with the description of the pion in terms of the set of wave functions of increasing twist. Obtained results are compared…

We present an improved calculation of $B\to$ light vector form factors from light-cone sum rules, including one-loop radiative corrections to twist-2 and twist-3 contributions, and leading order twist-4 corrections. The total theoretical…

In recent years, we used lattice QCD to calculate some quantities that were unknown or poorly known. They are the $q^2$ dependence of the form factor in semileptonic $D\to Kl\nu$ decay, the leptonic decay constants of the $D^+$ and $D_s$…

A new calculation of the neutron electric form factor is described. Preliminary results for the connected part on a $20^{3}\times 32$ lattice are presented. The methods for calculating the disconnected part are briefly described.

We use QCD sum rules to analyze the semileptonic transition $B \to \pi \ell \nu$ in the limit $m_b \to \infty$. We derive the dependence of the form factor $F_1(0)$ on the heavy quark mass, which is compatible with the expected dependence…