Related papers: $\Lambda_b \to (\Lambda_c,\,p)\,\tau\,\nu$ decays …
The analysis uses data from an integrated luminosity of approximately 172 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. The Lambda_b and B0 relative branching fractions are…
In this note, recent results of studies of semileptonic B meson decays from \babar are discussed and preliminary results given. In particular, a recent measurement of $\mathcal{B}(B \to D^{(*)}\tau \nu)$ and the ratio $\mathcal{B}(B \to…
The Standard Model predicts a branching ratio for the decay mode Bs -> mu mu of (3.4 +/- 0.5)10e-9, while some SUSY models predict enhancements up to 2 orders of magnitude. It is expected that at the end of its life Tevatron will set and…
We consider lepton-flavor violation in strangeness changing ($|\Delta S|=1$) semileptonic $\tau$-lepton decays arising from new physics encoded in a standard model effective Lagrangian. Its invariance under the standard model gauge group…
We study the exclusive $b \to u \ell^- \bar{\nu}_{\ell} (\ell=\tau,\mu,e)$ decays in the MSSM with and without R-parity violation. From the experimental measurements of branching ratios $\mathcal{B}(B^-_u \to \tau^- \bar{\nu}_{\tau})$,…
The recent Belle and BaBar measurements of the branching ratio of $B^+ \to \tau^+ \nu_\tau$ indicate a significant deviation from the Standard Model prediction. We demonstrate that this measurement has a serious impact on models with…
The ratio of branching fractions ${\cal{R}}(D^{*-})\equiv {\cal{B}}(B^0 \to D^{*-} \tau^+ \nu_{\tau})/{\cal{B}}(B^0 \to D^{*-} \mu^+\nu_{\mu})$ is measured using a data sample of proton-proton collisions collected with the LHCb detector at…
We report a measurement of the ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B}^0 \rightarrow D^{*+} \ell^- \bar{\nu}_{\ell})$, where $\ell$ denotes an electron or a muon. The results…
In this work, we study the decays $\Lambda_c \to (\Lambda, n) \ell^+ \nu_\ell$ ($\ell = \mu, e$) within a model-independent framework. We calculate the helicity amplitudes for all possible four-fermion operators, including the interactions…
We study the four-body semileptonic baryonic decay of $B^-\to \Lambda\bar p\nu\bar \nu$ in the standard model. We find that the decay branching ratio is $(7.9\pm 1.9)\times 10^{-7}$. Similar to the rare decays of $B^-\to K^{(*)-}\nu\bar…
The current world averages of the ratios $R_{D^{(*)}}$ are about $4\sigma$ away from their Standard Model prediction. These measurements indicate towards the violation of lepton flavor universality in $b\rightarrow c\,l\,\bar{\nu}$ decay.…
We present the differential rates and branching ratios of the radiative decays $\tau \to l \bar{\nu} \nu \gamma$, with $l=e$ or $\mu$, and $\mu \to e \bar{\nu} \nu \gamma$ in the Standard Model at next-to-leading order. Radiative…
I review the current status of measurements involving semi-tauonic $B$ meson decay at the $B$-factories. I briefly discuss the experimental methods and highlight the importance of background contributions especially from poorly understood…
We consider the most general new physics effective Lagrangian for b --> s l+ l-. We derive the upper limit on the branching ratio for the processes B_s --> l+ l- where l=e, mu, subject to the current experimental bounds on related…
We present a global analysis of the current $B$-meson flavor anomalies and extend it to the baryonic sector through the decay $\Lambda_b^0 \to \Lambda_c^+(\to \Lambda^0 \pi^+) \tau^-(\to \pi^- \nu_\tau)\bar{\nu}_\tau$. The lepton flavor…
The latest BaBar measurements of the ratios ${\cal R}(D^{(*)})=\displaystyle{\frac{{\cal B}(B \to D^{(*)} \tau {\bar \nu}_\tau)}{{\cal B}(B \to D^{(*)} \mu {\bar \nu}_\mu)}}$ deviate from the Standard Model predictions at the global level…
We have revisited the computations of the flavor violating leptonic decays of the $\tau$ and $\mu$ leptons into three lighter charged leptons in the Standard Model with non-vanishing neutrino masses. We were driven by a claimed unnaturally…
The $\bar{B}_s^0 \to D_s^{(*)+} l^- \bar{\nu}_l$ semileptonic decays were calculated in the framework of the standard model (SM) by employing the perturbative QCD (pQCD) factorization approach. We defined four ratios of the branching ratios…
In this paper, we studied the semileptonic $B/B_s \to (D^{(*)},D_s^{(*)}) l\nu_l$ decays in the framework of the standard model (SM) , by employing the perturbative QCD (PQCD) factorization formalism combining with the lattice QCD inputs of…
The experimental data on $b\to c\tau\bar\nu_\tau$ and $b\to s\ell^+\ell^-$ transitions exhibit sizeable discrepancies with the Standard Model expectations. We present an overview of the present status and discuss possible interpretations…