Related papers: Rare $\Lambda_b \rightarrow \Lambda l^+ l^- $ deca…

The branching fractions of the rare weak $B\to \pi l^+l^-(\nu\bar\nu)$ and $B\to\rho l^+l^-(\nu\bar\nu)$ decays are calculated in the framework of the relativistic quark model based on the quasipotential approach. The form factors…

The rare decay B_s -> mu^+ mu^- provides an important constraint on possible deviations from the Standard Model in b-s-l-l interactions. The present weighted average of its branching ratio measurements amounts to (3.34 \pm 0.27) x 10^-9,…

We calculate the contributions to the rare B-decays, $B \to X_{s,d} \nu \bar \nu$, $B_{s,d} \to l^+l^- $ from the unit-charged technipions. Within the considered parameter space we find that: (a) the enhancements to the branching ratios in…

We present the first measurements of branching fractions of rare tau-lepton decays, $\tau^- \rightarrow \pi^- \nu_{\tau} \ell^+ \ell^-$ ($\ell = e$ or $\mu$), using a data sample corresponding to 562 fb$^{-1}$ collected at a center-of-mass…

Using the most general, model independent form of the effective Hamiltonian, the exclusive, rare baryonic (Lambda_b -> Lambda l^+ l^- ~l=\mu,\tau) decay is analyzed. We study sensitivity of the branching ratio and lepton forward-backward…

Form factors of the rare $\Lambda_{b}(\Lambda_{b}^*)\to N\ell^{+}\ell^{-}$ decays are calculated in the framework of the light cone QCD sum rules by taking into account of the contributions from the negative parity baryons. Using the…

The relativistic quark model based on the quasipotential approach with the QCD-motivate potential is employed for the calculation of the form factors of the $\Lambda_c\to p$ rare weak transitions. Their momentum dependence is explicitly…

We study rare radiative leptonic decays $B_{(s)}\to e^+e^-\gamma$ and $B_{(s)}\to \mu^+\mu^-\gamma$ within relativistic quark model. In addition to previous analysis we give the estimations of the branching ratios for four values of the…

We present a systematic analysis for the rare baryonic exclusive decays of $\Lambda_b\to\Lambda l^+ l^- (l=e,\mu,\tau)$. We study the differential decay rates and the di-lepton forward-backward, lepton polarization and various CP…

Semileptonic and leptonic B decays are analyzed in the framework of the relativistic quark model. Special attention is payed to the decays involving $\tau$ lepton. It is found that the calculated particular decay branching fractions are…

First observations of the rare decays $B^+\rightarrow K^+\pi^+\pi^-\mu^+\mu^-$ and $B^+\rightarrow \phi K^+\mu^+\mu^-$ are presented using data corresponding to an integrated luminosity of $3.0\,{fb}^{-1}$, collected by the LHCb experiment…

By analyzing $e^+e^-$ collision data taken at center-of-mass energies $\sqrt{s}$ between 4.600 and 4.699 GeV with the BESIII detector at the BEPCII collider, corresponding to an integrated luminosity of $\rm 4.5~fb^{-1}$, we study the…

We study rare leptonic decays of vector $B$ mesons in the scalar leptoquark and family non-universal $Z^\prime$ models. We constrain these new couplings by using the measured branching fractions of $B_{s,d} \to \mu^+ \mu^-$ processes and…

The rare exclusive dileptonic $\Lambda_{b}\to \Lambda\ell^{+}\ell^{-}$ $(\ell =\mu, \tau)$ decays are investigated in the general two-Higgs-doublet model of type III. A significant enhancement to the branching ratios, differential branching…

Rare decays $\Lambda_b \to \Lambda \gamma$ and $\Lambda_b \to \Lambda l^{+} l^{-}$ (l= e, $\mu$) are examined. We use QCD sum rules to calculate the hadronic matrix elements governing the decays. The $\Lambda$ polarization in the decays is…

We have extracted the ratio $|V_{ub}|/|V_{cb}|$ from a combined study of the available inputs on $\bar{B}\to (\pi,\rho,\omega)\ell^- \bar{\nu}_{\ell}$ and $\bar{B}(\bar{B}_s)\to (D^{(\ast)}, D_s^{(\ast)})\ell^- \bar{\nu}_{\ell}$ ($\ell =…

We investigate rare special dileptonic decays of $ \Lambda_b$, $\Sigma_b$ and $\Xi_b $ baryons in the Standard Model and context of the general Two-Higgs-Doublet Model with Type III. Specifically, we consider the decays $ \Lambda_b…

Using the covariant constituent quark model previously developed by us we calculate the differential rate and the forward-backward asymmetries on the lepton and hadron side for the rare baryon decays Lambda_b -> Lambda l+ l- (l=e, mu, tau)…

We study the exclusive (Lambda_b -> \Lambda l^+ l^-) decay in the Appelquist, Chang, Dobrescu model within one universal extra dimension. We investigate the sensitivity of the branching ratio, lepton polarization and forward-backward…

We study the decays of $B_{s,d} \to l^+ l^- \gamma (l=e, \mu,\tau)$ within the light-front model. We calculate the tensor type form factors and use these form factors to evaluate the decay branching ratios. We find that, in the standard…