相关论文: Relations between $b\rightarrow c\tau \nu$ Decay M…
The need to map parton-level processes to color-neutral hadrons in a way that respects quark-hadron duality arises in several areas of physics, including in the semileptonic decays of $B$ mesons. Integrated over large regions of phase…
The ratio of the measured $\bar B\to D^{(*)}\ell\bar{\nu}$ decay rates for $\ell = \tau$ vs. $e,\mu$ deviate from the Standard Model (SM) by about $4\sigma$. We show that the data are in tension with the SM, independent of form factor…
In this work we study the semileptonic decays of $B_c$ meson. We evaluated $B_{c}\rightarrow D(D^{\ast})$, $B_{c}\rightarrow D_s(D_s^{\ast})$ and $B_{c}\rightarrow \eta_{c}(J/\psi)$ transitions form factors in the full kinematical region…
B meson rare decays ($B\to K(K^{*})l\bar l$ and $B\to K^*\gamma$) are analyzed in the framework of effective field theory of heavy quarks. The semileptonic and penguin type form factors for these decays are calculated by using the light…
Motivated by the recent investigation of neutrinoless $\tau$-lepton decays by the CLEO collaboration, we perform a systematic analysis of such decays in a possible new-physics scenario with heavy Dirac/Majorana neutrinos, including…
Considering the gluon condensate corrections, the form factors relevant to the semileptonic rare $B_c \rar D,D_s(J^{P}=0^{-}) l^{+}l^{-}$ with $l=\tau,\mu,e$ and $B_c \rar D,D_s(J^{P}=0^{-})\nu\bar{\nu}$ transitions are calculated in the…
We conduct a comprehensive study of the semileptonic decay process \(\Lambda \to p\,\ell\,\bar{\nu}_{\ell}\), focusing on the determination of all six vector and axial-vector form factors that govern the low-energy hadronic matrix elements…
The transition form factors of the semileptonic decay B_s into scalar D_{s_0}(2317) meson is calculated in the framework of 3-point QCD sum rule. The branching ratio is found to be ~10^(-3) for the (B_s -> D_{s_0}(2317) l nu_l) (l=e,mu)…
Heavy-to-heavy semileptonic decays, particularly the bottom-to-charm quark transitions, are essential for testing the Standard Model (SM) and extracting the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. These decays have been extensively…
The $B\rightarrow K_{2}^{\ast}(1430)l^{+}l^{-}$ $(l=\mu,\tau)$ decays are analyzed in the Standard Model extended to fourth generation of quarks (SM4). The decay rate, forward-backward asymmetry, lepton polarization asymmetries and the…
By using a constituent quark model we compute the form factors relevant to semileptonic transitions of B mesons into low-lying p-wave charmed mesons. We evaluate the q^2 dependence of these form factors and compare them with other model…
We calculate form-factor ratios between the semileptonic decays \bar{B}->D^+\ell^-\bar{\nu} and \bar{B}_s->D_s^+\ell^-\bar{\nu} with lattice QCD. These ratios are a key theoretical input in a new strategy to determine the fragmentation…
The semileptonic decay of heavy flavor mesons offers a clean environment for extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, which describes the CP-violating and flavor changing process in the Standard Model. The involved…
We have computed the form factors for B --> pi and D --> K(pi) semileptonic decays on the lattice by using full non-perturbative O(a) improvement, in the quenched approximation. Our results are expressed in terms of few parameters which…
In the covariant light-front quark model, we investigate the form factors of $B_c$ decays into $D, D^*, D_s, D_s^*, \eta_c, J/\psi, B, B^*, B_s, B_s^*$ mesons. The form factors in the spacelike region $q^2<0$ are directly evaluated. To…
The measurements of several lepton flavor universality (LFU) violating observables in the decays induced by the quark level transition $b \to c \tau \bar{\nu}$ provide an inkling of plausible physics beyond the standard model of electroweak…
We report on our determinations of $B\to \pi\ell\nu$, $B_s\to K \ell \nu$ and $B_s\to D_s \ell \nu$ semileptonic form factors. In addition we discuss the determination of $R$-ratios testing lepton-flavor universality and suggest an improved…
The tree-level $b\rightarrow c{\ell}\bar\nu_{\ell}$ based hadronic transitions have been on the focus of much attention since recording significant deviations of the experimental data, on the ratios of the branching fractions in $ \tau $…
We study some rare decays of $B$ meson involving the quark level transition $b \to q l^+l^- (q=d,s)$ in the scalar leptoquark model. We constrain the leptoquark parameter space using the recently measured branching ratios of $B_{s,d} \to…
We consider leptonic $B^-\to \ell^- \bar\nu_\ell$ and semileptonic $\bar B \to \pi \ell^- \bar\nu_\ell$, $\bar B \to \rho \ell^- \bar\nu_\ell$ decays and present a strategy to determine short-distance coefficients of New-Physics operators…