Related papers: Helicity amplitudes in $B \to D^{*} \bar{\nu} l$ d…
We derive relations between finite-volume matrix elements and infinite-volume decay amplitudes, for processes with three spinless, degenerate and either identical or non-identical particles in the final state. This generalizes the…
Helicity-dependent incoherent pion photoproduction in the reaction \vec \gamma \vec d\to \pi NN is studied in the framework of the diagrammatic approach. Contributions to the reaction amplitude from diagrams corresponding to impulse…
We calculate the $B\to D^{(*)}$ form factors in the heavy-quark and large-recoil limits in the perturbative QCD framework based on $k_T$ factorization theorem, assuming the hierachy $M_B\gg M_{D^{(*)}}\gg \bar\Lambda$, with the $B$ meson…
We present the joint helicity amplitudes for $J/\psi \to \Lambda \bar{\Lambda}$, $\Lambda(\bar\Lambda)$ decays to different final states in the helicity frame. Two observables to search for $CP$ violation in $J/\psi\to\Lambda\bar\Lambda$…
In order to extract some information on the CKM matrix element |Vcb|, we have to determine form factors in B decays. For this, we show that it is relevant to consider the non-forward amplitude between the heavy-light B and D mesons within…
Motivated by the persisting 'anomaly' in the measurement of $P_5^\prime$, we review hadronic uncertainties entering the angular observables of the decay $\bar B\to {\bar K}^*\mu^+\mu^-$. We argue that hadronic uncertainties could account…
Versus the standard model's t --> W b decay helicity amplitudes, three numerical puzzles occur at the 0.1 % level when one considers the amplitudes in the case of an additional (f_M + f_E) coupling of relative strength 53 GeV. The puzzles…
This paper describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using the decay $B^0\to D^{*-}\ell^+\nu_\ell$. We perform a combined measurement of this quantity and of the form factors $\rho^2$, $R_1(1)$,…
A class of meson decay modes sensitive to only one quark topology at leading G_F order (annihilation of valence quarks through a W) is described. No experimental observations, nor even upper limits, have been reported for these decays. This…
In the heavy-quark limit, the hadronic matrix elements entering nonleptonic $B$-meson decays into two light mesons can be calculated from first principles including ``nonfactorizable'' strong-interaction corrections. The $B\to\pi K,\pi\pi$…
In this work, we study $\Lambda_{b}\to\Lambda_{c}$ and $\Sigma_{b}\to\Sigma_{c}$ weak decays in the light-front quark model. As is well known, the key point for such calculations is properly evaluating the hadronic transition matrix…
The Weyl-van-der-Waerden spinor technique for calculating helicity amplitudes of massive and massless particles is presented in a form that is particularly well suited to a direct implementation in computer algebra. Moreover, we explain how…
It is shown that the helicity amplitudes A_1/2 and S_1/2 in the gamma N -> N(1535) reaction, can be well related by S_1/2 = -\frac{\sqrt{1+\tau}}{\sqrt{2}} \frac{M_S^2-M^2}{2 M_S Q} A_1/2 in the region Q^2 > 2 GeV^2, where M and M_S are the…
Rare $\Lambda_b\to\Lambda l^+l^-$ and $\Lambda_b\to\Lambda\gamma$ decays are investigated in the relativistic quark model based on the quark-diquark picture of baryons. The decay form factors are calculated with the account of all…
The radiative leptonic $B\to \gamma\ell\nu_{\ell}$ decay serves as an ideal platform to determine the $B$-meson inverse moment which is a fundamental nonperturbative parameter for the $B$ meson. In this paper, we explore precise QCD…
Within the framework of a nonrelativistic quark model we evaluate the six form factors associated to the \Lambda_b^0 \to \Lambda_c^+ l^- \bar{\nu}_l semileptonic decay. The baryon wave functions were evaluated using a variational approach…
In rare $B$ meson decays $B\rightarrow K \ell^+ \ell^-$, a possible contribution of $\ell^+\ell^-$ emission via photon from the "spectator" quark $q$ ($q=u,d$) in the $B$ meson $(q\bar{b})$ is investigated in addition to the conventional…
This work investigates the substructure of the $\Delta(1232)$ resonance in the $p\gamma^*\to \Delta(1232)$ process through helicity transition amplitudes within the quark model framework. We consider the involved baryons composed of three…
We describe a calculation of the two-photon decays of heavy vector-mesons, $B^*\to B\gamma\gamma$ and $D^*\to D\gamma\gamma$, by using the ``heavy meson chiral Lagrangian''. The decay amplitudes are expressed in terms of the strong coupling…
We present a holographic bottom up model for the thermal behavior of $ c \bar c$ vector mesons in a finite temperature and density plasma. There is a clear physical interpretation for the three imput energy parameters of the model. Two of…