Related papers: Double Lepton Polarization in $\Lambda_b -->\Lambd…
We present measurements of lepton (l) angular distributions in ttbar -> W+ b W- b -> l+ nu b l- nubar bbar decays produced in ppbar collisions at a center-of-mass energy of sqrt(s)=1.96TeV, where l is an electron or muon. Using data…
We study the effect of non-universal $Z'$ boson on the rare leptonic decay modes of $B_s^*$ mesons, mediated by $b arrow sll$ quark transition. Rare B decays are sensitive to various new physics operators. As B mesons are composite…
CP violating dipole moments of leptons vanish at least to three loop order and are estimated to be $({m_l\over Mev})\times 1.6\times 10^{- 40}$ e-cm in the standard model (SM), where $m_l$ is the mass of the lepton. However they can receive…
We analyze the flavor changing decay $h\rightarrow \mu \tau $ in the framework of a Two Higgs Doublet Model with a fourth generation of fermions (4G2HDM) which couples only to the heavy scalar doublet. We obtain that the respective…
The long-awaited $B_s\to \mu^+\mu^-$ mode has finally been observed at rate consistent with Standard Model, albeit lower by 1.2$\sigma$. There is some hint for New Physics in the rarer $B_d^0 \to \mu^+\mu^-$ decay, especially if the…
Analytic formulae for the one-loop order QCD corrections to the differential width of the semileptonic b decay are given with the tau polarization taken into account. Thence the polarization of tau is expressed by its energy and the…
We investigate the $B \rar K_{0}^{*}(1430) l^+ l^- $ transition in the Applequist-Cheng-Dobrescu model in the presence of a universal extra dimension. In particular, we calculate double lepton polarization asymmetries and branching ratio…
The most general model-independent analysis of the lepton polarization asymmetries in the rare B decay, $\Bstt$, is presented. We present the longitudinal, normal and transverse polarization asymmetries for the $\tau^+ $ and $\tau^-$, and…
We study the lepton flavor violating $\mu^- \to e^{-}2\gamma $ decay induced by the mediation of heavy leptons such as the excited and fourth generation leptons. We have examined the effects of these leptons in the $\mu^- \to e^{-}2\gamma $…
We study the dilepton forward-backward and the longitudinal, normal and transverse lepton polarization asymmetries in the heavy baryon decays of $\Lambda_b\to\Lambda l^+l^-$. We show that the asymmetries have a less dependence on the…
We study the effects of the identical leptons in the final state of the $B^+\to \ell^+ \ell^- \ell^+\bar\nu_{\ell}$ decay. The amplitude of the process is described by the same form factors as the amplitude of the ${B\to \ell \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…
In the minimal Standard Model (SM) with four generations (the so called SM4) and in "standard" two Higgs doublets model (2HDM) setups, e.g., the type II 2HDM with four fermion generations, the contribution of the 4th family heavy leptons to…
The possible transverse polarization of the $\tau$-lepton, which is $T$-odd and can be used to measure CP-violation, is estimated precisely in the radiative decay mode $B_c \to \tau \bar \nu_\tau \gamma$ with possible parameters for the…
We present a full angular distribution of the four body $\Lambda_b\to\Lambda(\to N\pi)\ell^+\ell^-$ decay where the leptons are massive and the $\Lambda_b$ is unpolarized, in an operator basis which includes the Standard Model operators,…
Most limits on the fourth generation heavy top quark (the t') are based on the assumed dominance of t' -> Wb, which is expected to be case in the minimal fourth generation framework with a single Higgs (the so called SM4). Here we show,…
Perturbative and nonperturbative QCD corrections to semileptonic B decay rates are calculated and given in analytical and numerical forms. We present the analytic expression for the double distribution in hadronic mass and electron energy…
Decays of B mesons into final states containing a tau lepton are sensitive to new charged-current interactions that break lepton-flavor universality. These decays have been studied only at e+e- colliders, where the low-background…
A search for the pair production of fourth generation b'-quarks was performed using data taken by the DELPHI detector at LEP-II. The analysed data were collected at centre-of-mass energies ranging from 196 to 209 GeV, corresponding to an…
Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b \to c l \bar{\nu}_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson…