Related papers: Testing the Standard Model in $B \to D \tau \bar \…
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…
Motivated by the anomalies present in $b \to s\,l^+\,l^-$ neutral current decays, we study the corresponding $B_c \to (D_s,\,D^{\ast}_s)\mu^+\mu^-$ decays within the standard model and beyond. We use a model independent effective theory…
We perform a model-independent fit of the short-distance couplings $C_{7,9,10}$ within the Standard Model set of $b\to s\gamma$ and $b\to s\bar\ell\ell$ operators. Our analysis of $B \to K^* \gamma$, $B \to K^{(*)} \bar\ell\ell$ and $B_s…
We study $B_c \to (D,\,D^{\ast})\,l\,\nu$ semileptonic decays mediated via $b \to u\,l\,\nu$ charged current interactions using the $B_c \to (D,\,D^{\ast})$ transition form factors obtained in the covariant light front quark model. We give…
Recently LHCb has measured the branching ratio of the rare decay of $B_s^0\rightarrow \mu^+ \mu^- $ as $2.9^{+1.1}_{-1.0} \times10^{-9}$ which is at par with the predicted standard model (SM) value. This result does not predict the absence…
b to s transitions are flavour-changing neutral current (FCNC) processes that play an important role in the search for physics beyond the Standard Model (SM). Contributions from virtual particles in the loop are predicted to deviate…
The rare decays B_s -> \mu^+\mu^- and B -> K^{(*)}\mu^+\mu^- are sensitive to new particles and couplings via their interferences with the standard model contributions. Recently, the upper bound on B(B_s -> \mu^+\mu^-) has been improved…
Within the perturbative QCD approach and ignoring the contributions of long distance and subleading penguin loops, we investigate $\bar B^0 \to D^0 \mu^+\mu^-$ decay in the large recoiling kinematic region in the Standard Model. At the tree…
Hints of lepton flavor universality violation observed in various flavor ratios such as $R_D$, $R_{D^*}$, $R_{J/\psi}$, $P_\tau^{D^*}$ and $F_L^{D^*}$ in $B\to D^{(*)}\,\ell \, \nu$ and $B_c\to J/\psi \, \ell\, \nu$ charge current decays…
We combine the results of CDF and DO searches for the rare decays B_s to mu+ mu- and B_d to mu+ mu-. The experiments use 364 pb-1 and 300 pb-1 of data respectively. The limits on the branching ratios are obtained by normalizing the…
The study of $B \to \tau^+ \tau^- (X)$ decays can provide us with a better understanding of the third generation, and can be a useful probe of physics beyond the standard model. We present a model independent analysis of these decays. We…
We present measurements of the semileptonic decays B- --> D0 tau- nubar_tau, B- --> D*0 tau- nubar_tau, B0bar --> D+ tau- nubar_tau, and B0bar --> D*+ tau- nubar_tau, which are sensitive to non--Standard Model amplitudes in certain…
At the present time, there are hints of new physics (NP) in several observables involving $b \to c \ell^- {\bar\nu}_\ell$ decays. In this talk, I describe measurable angular distributions for ${\bar B} \to D^* \mu^- {\bar\nu}_\mu$ and…
Recent measurements of the branching fraction for D_s -> l nu disagree with the Standard Model by around 2sigma. In this case the key aspect of the Standard Model is the calculation of the decay constant, f_{D_s}, with lattice QCD. This…
Impacts on new physics search from $\bbbar, \kkbar$ mixings and the rare decay $\kplusdecay$ are discussed. We show that, in a certain class of new physics models, the extra contributions to those processes can be parametrized by its ratio…
The Belle Collaboration has recently measured the complete set of angular coefficient functions for the exclusive decays $\bar B \to D^* (D \pi) \ell \bar \nu_\ell$, with $\ell=e,\,\mu$, in four bins of the parameter…
The rare B decays Bs(d)-->\mu\mu, B-->K*\mu\mu and Bs-->\phi\gamma are studied using up to \sim 0.41 fb^{-1} of pp collisions at \sqrt{s} = 7 TeV collected by the \lhcb experiment in 2010 and 2011. A search for the decays Bs(d)-->\mu\mu, is…
The current experimental status of the searches for the very rare decays $B^0_s \rightarrow \mu^+ \mu^-$ and $B^0 \rightarrow \mu^+ \mu^-$ is discussed. These channels are highly sensitive to various extensions of the Standard Model,…
A detailed analysis on the rare $\tau$ decay {\it via} $\taumue$ and $\taumus$ in the string models with $\e6$ symmetry is reported. It is found that $\Gamma(\taumue)\sim(6-7)\Gamma(\taumus)$ and these rates are in general about 1000 times…
We present a measurement of the branching fraction $B(D_s^+\to\mu^+\nu_\mu)$ using a 548 fb$^{-1}$ data sample collected by the Belle experiment at the KEKB $e^+e^-$ collider. The $D_s$ momentum is determined by reconstruction of the system…