Double Lepton Polarization in Λb−−>Λl+l−\Lambda_b -->\Lambda l^+ l^- Decay in the Standard Model with Fourth Generations Scenario

This study investigates the influence of the fourth generation quarks on the double lepton polarizations in \Lambda_b --> \Lambda \ell^+ \ell^- decay by taking |V^\ast_{t's}V_{t'b}|= 0.005,0.01,0.02,0.03 with phase \{60^\circ,90^\circ,120^\circ\}. We will try to obtain a constrain on the mass of the 4th generation top like quark t', which is consistent with the $b--> s\ell^+\ell^- rate . With the above mentioned parameters, we will try to show that the double lepton(muon, tau) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks(t', b') via its indirect manifestations in loop diagrams.Comment: 36 pages, 33 figure

Strong coupling constant of hb_{b} vector to the pseudoscalar and vector BcB_{c} mesons in QCD sum rules

The strong coupling constant g$_{h_{b}B_{c}^{PS}B_{c}^{V}}$ is calculated using the three-point QCD sum rules method. We use correlation functions to obtain these strong coupling constants with contributions of both B$_{c}^{PS}$ and B$_{c}^{V}$mesons as off-shell states. The contributions of two gluon condensates as a radiative correction are considered. The results show that g$_{h_{b}B_{c}^{PS}B_{c}^{V}}=8.80\pm 2.84 GeV^{-1}$and g$_{h_{b}B_{c}^{V} B_{c}^{PS}}=9.34\pm 3.12 GeV^{-1}$ in the $B_{c}^{PS}$ and $B_{c}^{V}$ off-shell state, respectively.Comment: 9 pages, 4 figure

Double-Lepton Polarization Asymmetries and Polarized Forward Backward Asymmetries in the Rare b \to s \ell^+ \ell^- Decays in a Single Universal Extra Dimension Scenario

We study the double-lepton polarization asymmetries and single and double-lepton polarization forward backward asymmetries of the rare b \to s \ell^+ \ell^- mode within the Standard Model and in the Appelquist-Cheng-Dobrescu model, which is a new physics scenario with a single universal extra dimension. In particular, we examine the sensitivity of the observables to the radius R of the compactified extra-dimension, which is the new parameter in this new physics model.Comment: 20 Pages, 15 Figures and 1 Tabl

Polarized lepton pair forward-backward asymmetries in (B -> K^* l^+ l^-) decay beyond the standard model

We study the polarized lepton pair forward-backward asymmetries in (B -> K^* l^+ l^-) decay using a general, model independent form of the effective Hamiltonian. We present the general expression for nine double-polarization forward-backward asymmetries. It is shown that, the study of the forward-backward asymmetries of the doubly-polarized lepton pair is a very useful tool for establishing new physics beyond the standard model.Comment: 29 pages, 18 figures, LaTeX formatte

On the mass and the decay constant of recently observed bound state hb(1P)h_b(1P)

The mass and decay constant of the ground state of spin singlet $b \bar{b}$ is calculated by using the QCD sum rules method. This meson is an axial vector $P$-wave named $h_b(1P)$ meson with $J^P =1^+$. It is found that the mass of this meson is $(m=9940\pm 37)$ MeV, which is consistent with the recent experimental data by Belle collaboration.Comment: 8 pages, 5 figure