Related papers: Lepton polarization in $B \to K_1 \ell^+ \ell^-$ D…

We present the fully general, model independent study of a few rare semileptonic $B$ decays that get dominant contributions from $W$-annihilation and $W$-exchange diagrams, in particular $B^0 \to \bar{D}^0 \ell^+\ell^-$, where $\ell =…

The exclusive $B_s -> \gamma l^+ l^- $ decay is analyzed in the framework of a family nonuniversal Z' model by calculating the differential branching ratio, double lepton polarizations and forward-backward asymmetries. Our results are…

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…

By analyzing 7.33\,fb$^{-1}$ of $e^+e^-$ collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we search for the semileptonic decays $D^+_s \to K_1(1270)^0 e^+\nu_e$ and $D^+_s \to…

The LHCb collaboration has recently presented their result on R_K = BR(B+ -> K+ mu+ mu-)/ BR(B+ -> K+ e+ e-) for the dilepton invariant mass bin m_{ll}^2 = 1-6 GeV^2 (l = mu, e). The measurement shows an intriguing 2.6 sigma deviation from…

A measurement of the ratio of branching fractions of the decays $B^+\to K^+\mu^+\mu^-$ and $B^+\to K^+e^+e^-$ is presented. The proton-proton collision data used correspond to an integrated luminosity of $5.0\,$fb$^{-1}$ recorded with the…

We examine the leptonic forward-backward and polarization (left-right) asymmetries in the dileptonic B -> X_s l^+ l^- decay when the momentum dependence of $\psi$ and $\psi'-\gamma$ conversion strength is taken into account. The results…

In this work, we investigate the semileptonic decays of $B_{(s)}$ meson to $D_{0}^{\ast}(2300)$, $D_{s0}^{\ast}(2317)$, $D_{s1}(2460)$, $D_{s1}(2536)$, $D_{1}(2420)$ and $D_{1}(2430)$ in the covariant light-front quark model (CLFQM). We…

In the past few years, several hints of lepton flavour universality (LFU) violation have emerged in the $b \to c \tau \bar\nu$ and $b \to s \ell^+ \ell^-$ data. Quite recently, the Belle Collaboration has reported the first measurement of…

The meson decays $B\to D\tau\nu$ and $B\to D^* \tau \nu$ are sensitive probes of the $b\to c\tau\nu$ transition. In this work we present a complete framework to obtain the maximum information on the physics of $B\to D^{(*)}\tau\nu$ with…

We study the four-body exclusive semileptonic baryonic $\bar B$ decays of $B^-\to p\bar p \ell^- \bar\nu_{\ell}$ ($\ell=e,\mu,\tau$) in the standard model. We find that their decay branching ratios are about $(1.0, 1.0,0.5)\times 10^{-4}$,…

This paper considers the implications of the heavy quark and chiral symmetries for the semi-leptonic decay $B \rightarrow D^* X \ell \bar \nu_\ell$. The general kinematic analysis for decays of the form {\sl pseudoscalar meson $\rightarrow$…

An amplitude analysis of the $B^+\to(\pi^+\pi^-)(K^0_{\mathrm{S}}\pi^+)$ decay is performed in the mass regions $0.30 < m_{\pi^+\pi^-} < 1.10\,\mathrm{GeV}/c^2$ and $0.75 < m_{K^0_{\mathrm{S}}\pi^+} < 1.20\,\mathrm{GeV}/c^2$, using $pp$…

We calculate the independent helicity amplitudes in the decays $B \to K^* \ell^+ \ell^-$ and $B \to \rho \ell \nu_\ell$ in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant $O(\alpha_s)$ and SU(3)…

The measurements of $R_{K^{(*)}}=\mathcal B(B\to K^{(*)}\mu^{+}\mu^{-})/\mathcal B(B\to K^{(*)}e^{+}e^{-})$ in recent years have hinted lepton flavor non-universality and thus drawn widespread attentions. If these anomalies are induced by…

We model-independently analyze the angular distributions of B -> K ll decays, l = e, mu, for low dilepton mass using QCD factorization. Besides the decay rate, we study the forward-backward asymmetry A_FB^l and a further observable, F_H^l,…

We will present the most recent results on leptonic B decays $B^{\pm(0)} \to K^{* \pm (0)} \nu \bar{\nu}$ and $B^{\pm} \to \mu^{\pm} \nu$, based on the data collected by the BaBar detector at PEP-II, an asymmetric $e^+ e^-$ collider at the…

Possible manifestation of the family non-universal Z' boson effects in lepton polarization in rare, exclusive baryonic "Lambda_b -> Lambda l+l-" decay is examined. It is observed that the double lepton polarizations P_TT and P_NN are…

We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell, \ell'=e, \mu$) in a supersymmetric extension of the Standard Model with R-parity violation. Estimates of the branching ratios…

The transitions $B_{s,d}\rightarrow \ell^+\ell^-$ (for $\ell=e, \mu, \tau$), although extremely suppressed within the SM, are exceptionally clean channels particularly sensitive to New Physics contributions. So far only the branching ratio…