相关论文: Double Lepton Polarization in $\Lambda_b -->\Lambd…

We summarize recent results on QCD corrections to various observables in semileptonic $b$ quark decays. For massless leptons in the final state we present effects of such corrections on triple differential distribution of leptons which are…

We study the doubly-polarized lepton pair forward-backward asymmetries in (Lambda_b -> Lambda l^+ l^-) decay using a general, model independent form of the effective Hamiltonian. We present the general expression for nine…

We show that the transverse polarization asymmetry of the $\tau$-lepton in the decay $t\rightarrow b \tau \nu$ is extremely sensitive to CP violating phases arising from the charged Higgs exchange in the Weinberg model of CP…

If the fourth generation fermions exist, the new quarks could influence the branching ratio of the rare $B\to K^{*}\nu\bar{\nu}$ decay. Two possible solutions of the fourth generation CKM factor $(V^{*}_{\acute{t}s}V_{\acute{t}b})^(\pm)$…

In the Standard Model, b quarks produced in e^+e^- annihilation at the Z^0 peak have a large average longitudinal polarization of -0.94. Some fraction of this polarization is expected to be transferred to b-flavored baryons during…

In the presence of an electric dipole coupling of t-tbar to a photon, and an analogous "weak" dipole coupling to the Z, CP violation in the process e+e- --> t tbar results in modified polarization of the top and anti-top. This polarization…

We study the spin polarizations of both tau leptons in the decay b -> s tau+ tau-. In addition to the polarization asymmetries involving a single tau, we construct asymmetries for the case where both polarizations are simultaneously…

We comment on a recent suggestion by Amundson, Rosner, Worah and Wise to test the chirality of the $b$-quark decay coupling via polarized $\Lambda_b$ baryons produced in $e^+e^-\rightarrow Z\rightarrow \Lambda_b +X$. We study the effect of…

We investigate the double Dalitz decays $B_s \to l^+ l^- l'^+ l'^-$ on the basis of the effective Hamiltonian for the transition $b \bar{s} \to l^+ l^-$, and universal form factors suggested by QCD. The correlated mass spectrum of the two…

The lepton polarization asymmetry in the B\to\ell^{+}\ell^{-} decay, when one of the leptons is polarized, is investigated using the most general form of the effective Hamiltonian. The sensitivity of the asymmetry to the new Wilson…

We study the potential of $B\to K^{(*)} \ell^+\ell^-$ decays as tests of the standard model. After discussing the reliability of theoretical predictions for the hadronic matrix elements involved, we examine the impact of different new…

The double lepton pair decay modes of the K_L meson are analyzed including all contributions of order p^6 in Chiral Perturbation Theory. The experimentally established e^+ e^- e^+ e^- mode and the recently observed e^+ e^- mu^+ mu^- mode…

We analyze the recent experimental evidence for an excess of $\tau$-lepton production in several exclusive semileptonic $B$-meson decays in the context of two-Higgs-doublet models. These decay modes are sensitive to the exchange of charged…

We continue our previous determination of the masses of the sequential fourth generation quarks in an extension of the Standard Model, and predict the mass $m_4$ ($m_L$) of the fourth generation neutrino $\nu_4$ (charged lepton $L$) by…

The polarization of $\Lambda_b$ baryon has been measured in ALEPH, OPAL and DELPHI experiments. A significant loss on the transfer of the $b$ quark polarization to the $\Lambda_b$ baryon polarization has been noticed. This implies that the…

We study the rare $\Lambda_b\to\Lambda\mu^+\mu^-$ decay in the Standard Model and beyond. Beyond the Standard Model we include new vector and axial-vector operators, scalar and pseudo-scalar operators, and tensor operators in the effective…

In the upcoming LHC Run 2, at $\sqrt{s} \sim13$ TeV, it is suggested to seek unusually charged ($Q= -4/3$ and $+5/3$) quarks with mass $M_Q \sim 3$ TeV which carry lepton number ($L = +2$ and $-2$ respectively) and decay superweakly to a…

Most general tbW couplings were investigated in the process \gamma \gamma -> ttbar -> l^{+-} X for unpolarized photon beams. The double angular and energy distribution of the lepton was calculated and an optimal-observable analysis on it…

The apparent excess of $Z \rightarrow b \bar b$ events at LEP may be an indication of new physics beyond the standard model. However, in either the two-Higgs-doublet model or the minimal supersymmetric standard model, any explanation would…

We study the exclusive (Lambda_b -> \Lambda l^+ l^-) decay in the Appelquist, Chang, Dobrescu model within one universal extra dimension. We investigate the sensitivity of the branching ratio, lepton polarization and forward-backward…