Related papers: One Loop Calculations of Rare B-decays Beyond the …
The mixing of the known quarks with new heavy singlets can modify significantly some observables with respect to the Standard Model predictions. We analyse the range of deviations permitted by the constraints from precision electroweak data…
Vector-like quarks (VLQ) that couple preferentially to third-generation Standard Model (SM) quarks are a well-motivated extension of the SM, which could solve in particular the hierarchy problem. While VLQs can be produced in pairs via the…
If no new physics signals are found, in the coming years, at the Large Hadron Collider Run-2, an increase in precision of the Higgs couplings measurements will shift the dicussion to the effects of higher order corrections. In Beyond the…
Recently, we studied the branching ratios of rare K and B decays in models with Minimal Flavor Violation (MFV) using the presently available information from the universal unitarity triangle analysis and from the measurements of Br(B -> Xs…
The rare decays $B_{s(d)} \to \mu^+\mu^-$ play a key role for the testing of the Standard Model. An overview of the most recent theoretical predictions of the corresponding branching ratios is given, emphasizing that the sizable decay width…
The branching fractions of the semileptonic and rare $B_s$ decays are calculated in the framework of the QCD-motivated relativistic quark model. The form factors of the weak $B_s$ transitions are expressed through the overlap integrals of…
We study the potential effect of anomalous couplings of the third generation quarks to gauge bosons in rare B decays. We focus on the constraints from flavor changing neutral current processes such as $b\to s\gamma$ and $b\to s…
We study the flavor physics in two extensions of the quark sector of the Standard Model (SM): a four generation model and a model with a single vector--like down--type quark (VDQ). In our analysis we take into account the experimental…
The exotic states $X_{0,1}(2900)$ with the quark flavor of $cs\bar{u}\bar{d}$ are recently observed in the mass spectrum of $D^+K^-$ in $B^-\to D^-D^+K^-$ by the LHCb collaboration. To explore the nature of $X_{0,1}(2900)$, except for…
We investigate the decays of the excited $(b\bar q)$ mesons as probes of the short-distance structure of the weak $\Delta B=1$ transitions. These states are unstable under the electromagnetic or strong interactions although their widths are…
Rare decay modes of the newly discovered standard-model-like Higgs boson $h$ may test the flavor changing couplings in the leptoquark sector through the process $h \to \tau^\mp\mu^\pm$. Motived by the recently reported excess in LHC data…
The exclusive semileptonic $B\to \pi(\rho) e\nu$ decays are studied in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The large recoil momentum of the final $\pi(\rho)$ meson…
We present a measurement of the branching fraction for the rare decays B->rho e nu and extract a value for the magnitude of Vub, one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for…
We investigate the effect of general flavour mixing among squarks on the rare decays $\bar{B}\to X_s\gamma$, $\bar{B}_s\to\mu^+\mu^-$ and $\bar{B}_s-B_s$ mixing beyond the leading order in perturbation theory. We include all large…
The $b \rightarrow s \gamma$, $b \rightarrow d \gamma$ and $b \rightarrow s \ell^+ \ell^-$ processes are allowed at higher order via the electroweak loop or box diagrams in the Standard model. It is sensitive probe to search for new physics…
We study the decay of the exotic Vector-Like Quarks (VLQs) $X$ and $Y$, with $5/3$ and $-4/3$ units of electric charge, respectively, within the 2-Higgs Doublet Model (2HDM). Building on our previous studies of Vector-Like Top and Bottom…
The rare decays {$B^- \to \tau \bar\nu$}, \mbox{$B \to \tau^+ \tau^-$}, {$b \to X \nu \bar\nu$} and \mbox{$b \to X \tau^+ \tau^-$} all contain third generation leptons in the final state, and hence are sensitive to new physics that couples…
We study the effect of supersymmetric contributions to the effective quark transition $b\to s\gamma\gamma$, including leading order QCD effects. We apply the discussion to the decay $B_s\to\gamma\gamma$. Even though one-particle irreducible…
The rare decay $b\to ss\bar{d}$ is studied in a vector quark model by adding the contributions from exotic vector-like quarks. We find that the contribution from box diagrams amounts to $10^{-9}$ in the branching ratio, while the…
We review some selected rare B decays calculated in next-to-leading order accuracy in the Standard Model (SM). These include the radiative decays $B \to (X_s,K^*,\rho)\gamma$ and the semileptonic decays $B \to (X_s,K,K^*) \ell^+ \ell^-$,…