Related papers: Testing the Standard Model in $B \to D \tau \bar \…
Recently hints of lepton flavor non-universality emerged when the BaBar Collaboration observed deviations from the standard model predictions in $R(D^{(*)}) \equiv {\cal B}({\bar B} \to D^{(*)+} \tau^- {\bar\nu}_\tau) / {\cal B}({\bar B}…
In the standard model (SM), we re-investigate the rare decay $B\to \phi\pi$, which has been viewed as an ideal probe to detect the new physics signals beyond the SM. Contributions in the naive factorization method, the radiative…
Using 482~pb$^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of $\sqrt{s} = 4.009$ GeV with the BESIII detector, we measure the branching fractions of the decays $D_s^+\to\mu^+\nu_\mu$ and $D_s^+\to\tau^+\nu_\tau$. By…
The decay modes $\bar{B}\to D^{(*)}\tau\bar{\nu}_{\tau}$ are sensitive to charged scalar effects, such as the charged Higgs effects. In this paper we suggest a method to determine their effects by using the ratio of branching fractions and…
Recently, Belle II reported on the first measurement of $\mathcal{B}(B^\pm\to K^\pm \nu\bar{\nu})$ which appears to be almost $3\sigma$ larger than predicted in the Standard Model. We point out the important correlation with…
Very compelling deviations in the recently observed lepton nonuniversality observables $\big (R_{D^{(*)}}, R_{K^{(*)}}, R_{J/\psi} \big )$ of semileptonic $B$ meson decays from their Standard Model predictions hint towards the presence of…
Rare decays mediated by $b \to s \nu \bar \nu$ transitions have been reported by the Belle II experiment. The branching ratio of the decay $B^+ \to K^+ \nu \bar \nu$ is found to be enhanced with respect to the standard model value. If taken…
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 $\mathcal{B}(B^-_u \to \tau^- \bar{\nu}_{\tau})$,…
An analysis of the rare B decays $B\to K^{(*)}\nu\bar\nu$ is presented both within the SM and beyond. The SM predictions for the branching ratios are updated and uncertainties reduced. For the NP analysis both a model independent approach…
In recent times, the charged-current mediated semileptonic $b \to c \tau \bar \nu_\tau$ processes have attracted a lot of attention after the observation of lepton non-universality ratios, $R_{D^{(*)}}$, $R_{J/\psi}$ and the measurements on…
We investigate how far a new physics scenario affecting primarily the third generation fermions can ameliorate the tension between B-decay observables and Standard Model expectations. Adopting a model-independent approach, we find that…
The measurement of $R_D$ ($R_{D^*}$), the ratio of the branching fraction of $\overline{B} \to D \tau \bar{\nu}_\tau (\overline{B} \to D^* \tau \bar{\nu}_\tau)$ to that of $\overline{B} \to D l \bar{\nu}_l (\overline{B} \to D^* l…
We study the decays of $B\to K^{(*)} \ell^{+} \ell^{-}$ in split supersymmetry with R-parity violation. We find that the decay branching ratio of $B\to K\tau^+\tau^-$ in the new physics model due to the scalar interactions can be $1.8\times…
The measurement of $R_D$ ($R_{D^*}$), the ratio of the branching fraction of $\overline{B} \to D \tau \bar{\nu}_\tau (\overline{B} \to D^* \tau \bar{\nu}_\tau)$ to that of $\overline{B} \to D l \bar{\nu}_l (\overline{B} \to D^* l…
The Belle and Babar experiments have measured the branching fractions for B+ -> tau+ nu and Ds+ -> mu+ nu decays. From these measurements one can extract the B+ and Ds+ decay constants, which can be compared to lattice QCD calculations. For…
B physics is sensitive to the effects of Higgs bosons in the Minimal Supersymmetric Standard Model, if the parameter tan beta is large. I briefly summarise the role of B -> mu+ mu- and B -> tau nu in the hunt for new Higgs effects and…
Recently, the LHCb collaboration reported the first evidence for the decay $B_s^0 \rightarrow \mu^+ \mu^-$. A branching ratio of $\mathcal{B}(B_s^0 \rightarrow \mu^+ \mu^-) = (3.2^{+1.5}_{-1.2}) \times 10^{-9}$ is given. Using the newest…
We speculate about the possible interpretations of the recently observed excess in the $h \to \tau \mu$ decay. We derive a robust lower bound on the Higgs boson coupling strength to a tau and a muon, even in presence of the most general new…
We discuss possible new physics (NP) effects beyond the standard model (SM) in the exclusive decays $\bar{B}^0 \to D^{(\ast)} \tau^- \bar{\nu}_{\tau}$. Starting with a model-independent effective Hamiltonian including non-SM four-Fermi…
We investigate the ${\bar B_s} \to \mu^+ \mu^-$ decay in the presence of a light stabilized radion in Randall-Sundrum model. The branching ratio $BR({\bar B_s} \to \mu^+ \mu^-)$ in the standard model is found to be $3.17 \times 10^{-9}$…