相关论文: Quark model study of the semileptonic B -> pi deca…
The semileptonic decay B->pi is studied starting from a simple quark model that takes into account the effect of the B* resonance. A novel, multiply subtracted, Omnes dispersion relation has been implemented to extend the predictions of the…
The semileptonic $B\to \pi l^+ \nu_l$ decay is studied starting from a simple quark model which includes the influence of the $B^*$ pole. To extend the predictions of a nonrelativistic constituent quark model from its region of…
We use a multiply-subtracted Omnes dispersion relation for the form factor f^+ in B->pi semileptonic decay, allowing the direct input of experimental and theoretical information to constrain its dependence on q^2. Apart from these inputs we…
The exclusive semileptonic $B\to \pi(\rho) e\nu$ decays are studied in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The large recoil momentum of the final $\pi(\rho)$ meson…
Semileptonic decays $D\to K,K^*,\pi,\rho$, $D_s\to \eta,\eta',\phi$, and $B\to D,D^*,\pi,\rho$ are analyzed within the dispersion formulation of the quark model. The form factors at timelike $q$ are derived by the analytical continuation…
Quark model results for the $B\to \pi,\rho$ decays are analysed, making use of the dispersion formulation of the model: The form factors at $q^2>0$ are expressed as relativistic invariant double spectral representation over invariant masses…
We update the extraction of |Vub| from exclusive semileptonic B to pi decays, combining experimental partial branching fraction information with theoretical form factor calculations, using the recently revised HPQCD results for the form…
We study the $f^+$ form factor for the $\bar B_s\to K^+\ell^-\bar\nu_\ell$ semileptonic decay in a nonrelativistic quark model. The valence quark contribution is supplemented with a $\bar B^*$-pole term that dominates the high $q^2$ region.…
We use Omnes representations of the form factors f_+ and f_0 for exclusive semileptonic B to pi decays, paying special attention to the treatment of the B* pole and its effect on f_+. We apply them to combine experimental partial branching…
Some emerging difficulties in the theoretical description of exclusive semileptonic $\bar B$ decays are discussed in the context of the quark model. While there are no unambiguous problems at this time, I discuss physics beyond the valence…
We evaluate the form factors describing the exclusive decay B-> pi l nu by using a Constituent Quark-Meson model based on an effective quark-meson Lagrangian (CQM). The model allows for an expansion in the pion momenta and we consider terms…
B meson semileptonic decays are a crucial tool in our studies of the quark mixing parameters Vcb and Vub. The interplay between experimental and theoretical challenges to achieve precision in the determination of these fundamental…
The spectra and form factors of exclusive semi-leptonic decays of B-meson are analyzed, taking account of confined effects of quarks by the Covariant Oscillator Quark Model. The predicted B --> (D*,D)l nubar_l spectra with the conventional…
We study the $f^+$ form factor for the semileptonic $\bar B_s\to K^+\ell^-\bar\nu_\ell$ decay in a constituent quark model. The valence quark estimate is supplemented with the contribution from the $\bar B^*$ pole that dominates the high…
We reevaluate the $B\to\rho\,l^+\nu_l$ decay width as a full $B\to\pi\pi\,l^+\nu_l$ four-particle decay, in which the two final pions are produced via an intermediate $\rho$ meson. The decay width can be written as a convolution of the…
Long-distance effects in exclusive rare semileptonic transitions B -> (K, K*) are analysed within a relativistic quark model. The meson transition form factors, describing the meson amplitudes of the effective weak Hamiltonian, are…
The rate of the semileptonic decay b to c l v is calculated with order alphas^2 accuracy, as an expansion around the limit of equal masses of the b and c quarks. Recent results obtained around the limit of the c-quark much lighter than b…
Precision tests of the CKM mechanism and searches for new physics in the flavour sector require dedicated QCD calculations of decay widths and spectra. Significant progress has been achieved in recent years in computing inclusive B decay…
Theoretical predictions for inclusive semileptonic B decay rates are rewritten in terms of the Upsilon(1S) meson mass instead of the b quark mass, using a modified perturbation expansion. This method gives theoretically consistent and…
We report on determinations of |Vub| resulting from studies of the branching fraction and q^2 distributions in exclusive semileptonic B decays that proceed via the b->u transition. Our data set consists of the 9.7x10^6 BBbar meson pairs…