Double-lepton Polarization Asymmetries Research Articles

Double-lepton polarization asymmetries inBs→ϕℓ+ℓ−decay in the fourth-generation standard model

In this paper, we investigate the effects of the fourth generation of quarks on the double-lepton polarization asymmetries in the ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ decay. It is shown that most of these asymmetries in ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ are quite sensitive to the fourth-generation parameters. We also compare these asymmetries with those of $B\ensuremath{\rightarrow}K{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ decay and show that $⟨{P}_{LT}⟩$, $⟨{P}_{TL}⟩$, $⟨{P}_{NN}⟩$, and $⟨{P}_{TT}⟩$ in ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ decay are more sensitive to the fourth-generation parameters in comparison with those of $B\ensuremath{\rightarrow}K{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ decay. We conclude that an efficient way to establish the existence of the fourth generation of quarks could be the study of these asymmetries in the ${B}_{s}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ decay.

Double-lepton polarization asymmetries and polarized forward backward asymmetries in the rareb→sℓ+ℓ−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 $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ 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.

Double-lepton polarization asymmetries in Λb→Λℓ+ℓ- decay in universal extra dimension model

Double-lepton polarization asymmetries in Λb→Λℓ+ℓ- decay are calculated in the universal extra dimension (UED) model. It is found that numerous double-lepton polarization asymmetries are very sensitive to the UED model and therefore can be a very useful tool for establishing new physics predicted by the UED model.

Double-lepton polarization asymmetries in the exclusiveB→ρℓ+ℓ−decay beyond the standard model

The double-lepton polarization asymmetries in (B -> rho l^+ l^-) decay is analyzed in a model independent framework. The general expressions for nine double-polarization asymmetries are calculated. It is shown that the study of the double-lepton polarization asymmetries proves to be very useful tool in looking for new physics beyond the standard model.

Double-lepton polarizations inB→ℓ+ℓ−γdecay

Double-lepton polarization asymmetries in the $B\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}\ensuremath{\gamma}$ decay are calculated using the most general, model independent form of the effective Hamiltonian including all possible forms of the interaction. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the averaged double-lepton polarization asymmetries at LHC is also discussed.

Lepton polarization asymmetries forB→K*ell+ell−: A Model Independent approac

In this work we shall derive expressions for the single and double lepton polarization asymmetries for the exclusive decay $B \to K^* \ell^+ \ell^-$, using the most general model independent effective Hamiltonian. We have conducted this study with this particular channel as it has the highest branching ratio among the various purely leptonic and semi-leptonic decay modes, making this mode particularly useful for studying physics beyond the SM. We have also analyzed the effects on these polarization asymmetries, and hence the physics underlying it, when complex phases are included in some of the Wilson coefficients.

Double-lepton polarization asymmetries in $\Lambda_b \rightarrow \Lambda \ell^ + \ell^-$ decay

Double-lepton polarization asymmetries in (Lambda_b -> Lambda l^+ l^-) decay are calculated using a general, model independent form of the effective Hamiltonian. The sensitivities of these asymmetries to the new Wilson coefficients are studied in detail. Furthermore, the correlations between averaged double-lepton polarization asymmetry and branching ratio are analyzed. It is shown that there exist certain regions of the new Wilson coefficients where new physics can be established by measuring the double-lepton polarization asymmetries only.

Double-lepton polarization asymmetries in the $B \to K \ell^ + \ell^-$ decaybeyond the standard model

General expressions for the double-lepton polarizations in the (B -> K l^+ l^-) decay are obtained, using model independent effective Hamiltonian, including all possible interactions. Correlations between the averaged double-lepton polarization asymmetries and the branching ratio, as well as, the averaged single-lepton polarization asymmetry are studied. It is observed that, study of the double-lepton polarization asymmetries can serve as a good test for establishing new physics beyond the Standard Model.