arXiv subjects
Publications and source records attributed to E. O. Iltan.
We calculate the new physics effects to the branching ratios of the lepton flavor conserving decays Z -> l^+ l^- in the framework of the general two Higgs Doublet model. We predict the upper limits for the couplings |\barξ^{D}_{N,μτ}| and |\barξ^{D}_{N,ττ}| as 3\times 10^2 GeV and 1\times 10^2 GeV, respectively.
We study the CP violating asymmetry, the forward-backward asymmetry of the lepton pair and the CP asymmetry in the forward backward asymmetry for the exclusive decay $B --> K^* τ^+ τ^- in the general two Higgs doublet model including the neutral Higgs boson effects. We analyse the dependencies of these quantities on the model III parameters. We found that the physical parameters studied above are at the order of the magnitude 1% and neutral Higgs boson effects are detectable for large values of the coupling \barξ_{N,ττ}^D.
We study the Electric Dipole moment of b quark in the general two Higgs Doublet model (model III) and three Higgs Doublet model with O(2) symmetry in the Higgs sector. We analyse the dependency of this quantity to the new phase coming from the complex Yukawa couplings and masses of charged and neutral Higgs bosons. We see that the Electric Dipole moment of b quark is at the order of 10^{-20} e cm, which is an extremely large value compared to one calculated in the SM and also two Higgs Doublet model (model II) with real Yukawa couplings.
We calculate the electric dipole moment of electron using the experimental result of muon electric dipole moment and upper limit of the BR(μ--> eγ) in the framework of the general two Higgs doublet model. Our prediction is 10^{-32} e-cm, which lies in the experimental current limits. Further, we obtain constraints for the Yukawa couplings \barξ^{D}_{N,τe} and \barξ^{D}_{N,τμ}. Finally we present an expression which connects the BR(τ\to μγ) and the electric dipole moment of τ-lepton and study the relation between these physical quantities.
We study the decay width and forward-backward asymmetry of the lepton pair for the inclusive decay b --> s τ^+ τ^- in the two Higgs doublet model with three level flavor changing neutral currents (model III) and analyse the dependencies of these quantities on the model III parameters, including the leading order QCD corrections. We found that there is a considerable enhancement in the decay width and neutral Higgs effects are detectable for large values of the parameter \barξ_{N,ττ}^D.
We study the decay width and CP-asymmetry of the inclusive process b--> s g g (g denotes gluon) in the three and two Higgs doublet models with complex Yukawa couplings. We analyse the dependencies of the differential decay width and CP-asymmetry to the s- quark energy E_s and CP violating parameter θ. We observe that there exist a considerable enhancement in the decay width and CP asymmetry is at the order of 10^{-2}. Further, it is possible to predict the sign of C_7^{eff} using the CP asymmetry.
We study the decay width of the inclusive process b --> s g g in the two Higgs doublet model with three level flavor changing neutral currents (model III). We analyse the dependencies of the differential decay width to the s quark energy E_s and model III parameters, charged Higgs mass m_{H^{\pm}} and Yukawa coupling \barξ_{N,bb}^D. We observe that there exist a considerable enhancement in the decay width for the relevant process. This enhancement can be reduced by choosing C_7^{eff} as negative and increasing the lower bound of m_{H^{\pm}} to the large values, such as 800 GeV . This is an interesting result which gives an idea on the mass m_{H^{\pm}} and sign of C_7^{eff}.
The radiative B ->τ^+ τ^- γdecay is investigated in the framework of the two Higgs doublet model . The dependence of the differential branching ratio on the photon energy and the branching ratio on the two Higgs doublet model parameters, m_{H^\pm} and \tan β, are studied. It is shown that there is an enhancement in the predictions of the two Higgs doublet model compared to the Standard model case. We also observe that contributions of neutral Higgs bosons to the decay are sizable when \tanβis large.
We study CP asymmetry for the exclusive decay B --> K^* l^+ l^- in the two Higgs doublet model with three level flavor changing neutral currents (model III). We analyse the dependency of this quantity to the new phase coming from the complex Yukawa couplings in the theory and we find that there exist a considerable CP violation for the relevant process. Further, we see that the sign of the Wilson coefficient C_7^{eff} can be determined by fixing dilepton mass. Therefore, the future measurements of CP asymmetry for B --> K^* l^+ l^- decay will give a powerful information about the sign of Wilson coefficient C_{7}^{eff} and the new physics beyond the SM.
We study the b --> sγdecay including the next to leading QCD corrections in the two Higgs doublet model with flavor changing neutral currents at the tree level. We find the constraints to the flavor changing parameters of the model, using the experimental results on the branching ratio of B --> X_s γdecay, provided by the CLEO Collaboration, the restrictions coming from the ΔF=2 (F=K,D,B) mixing and the ρparameter.
We study the differential Branching ratio and CP asymmetry for the exclusive decay B --> K^* l^+ l^- in the three Higgs doublet model with additional global O(2) symmetry in the Higgs sector. We analyse dilepton mass square q^2 dependency of the these quantities. Further, we study the effect of new parameter of the global symmetry in the Higgs sector on the differential branching ratio and CP asymmetry. We see that there exist an enhancement in the branching ratio and a considerable CP violation for the relevant process. In addition to this, we realize that fixing dilepton mass gives information about the sign of the Wilson coefficient C_7^{eff}.Therefore, the future measurements of the CP asymmetry for B\to K^* l^+ l^- decay will give a powerful information about the sign of Wilson coefficient C_{7}^{eff} and new physics beyond the SM.
We study the decay width, forward-backward asymmetry and the longitudinal lepton polarization for the exclusive decay B --> K^* l^+ l^- in the two Higgs doublet model with three level flavor changing neutral currents (model III) and analyse the dependencies of these quantities on the the selected parameters, ξ^{U,D}, of model III including the next to leading QCD corrections. It is found that to look for charged Higgs effects, the measurements of the branching ratio, forward-backward asymmetry and the longitudinal lepton polarization for the decay B --> K^* l^+ l^- are promising.
We calculate the leading logarithmic QCD corrections to the matrix element of the decay b --> d e^+ e^- in the two Higgs doublet model with tree level flavor changing currents (model III). We continue studying the differential branching ratio and the CP violating asymmetry for the exclusive decays B --> πe^+ e^- and B --> ρe^+ e^- and analysing the dependencies of these quantities on the selected model III parameters, ξ^{U,D}, including the leading logarithmic QCD corrections. Further, we present the forward-backward asymmetry of dileptons for the decay B --> ρe^+ e^- and discuss the dependencies to the model III parameters. We observe that there is a possibility to enhance the branching ratios and suppress the CP violating effects for both decays in the framework of the model III. Therefore, the measurements of these quantities will be an efficient tool to search the new physics beyond the SM.
We calculate the leading logarithmic QCD corrections to the decay B_{s} -->γγin the two Higgs doublet model with tree level flavor changing currents (model III) including O_7 type long distance effects. Further, we analyse the dependencies of the branching ratio Br(B_{s} --> γγ)$ and the ratio of CP-even and CP-odd amplitude squares, R=|A^{+}|^2/|A^{-}|^2, on the charged Higgs mass m_{H^{\pm}} and the selected model III parameters ξ^{U,D} including the leading logarithmic QCD corrections. It is found that to look for charged Higgs effects, the measurement of the branching ratio Br(B_{s} --> γγ)$ is promising.
We present leading logarithmic QCD corrections to the decay B_s --> γγin the Standard Model. Further, the form factor F_{1}(0) of B_s --> ϕγis calculated in the framework of QCD sum rules and found to be in agreement with the result existing in the literature. Using Vector Meson Dominance model, the amplitude for B_s --> ϕγ-->γγis calculated as an estimate of the O_7-type contributions to the long-distance effects in the B_s --> γγdecay. The resulting branching ratio B(B_s --> γγ)_{SD+LD_{O_7}} is analysed in view of its strong dependence on the non-perturbative parameter $\barΛ_s$, describing bound state effects, and the renormalization scale $μ$. .
We calculate the leading logarithmic QCD corrections to the decay B_s --> γγin the two Higgs doublet model (2HDM) including O_7 type long distance effects and estimate the restrictions of the 2HDM parameters, tanβand m_H, using the experimental data of B --> X_s γdecay provided by the CLEO collaboration. A lower bound for the charged Higgs mass m_H as a function of the renormalization scale μis given for 2HDM model II. We further present the dependencies of the branching ratio Br(B_s --> γγ) and the ratio |A^{+}|^2/|A^{-}|^2 on m_H and tanβincluding leading logarithmic QCD corrections. The dependence on the renormalization scale is found to be strong for both ratios. An additional uncertainty arises from the variation of the parameters of the bound state model, (m_b, \barΛ_s). We see, that to look for charged Higgs effects the measurement of the branching ratio Br(B_s --> γγ) is promising.
The B_{s} --> ϕψdecay is modeled through the inclusive b --> sψdecay. Using the Vector Meson Dominance model, the amplitude for the chain process B_{s} --> ϕψ--> ϕγ--> γγis estimated and it is found to be at most 4 % of the corresponding amplitude from the O_7 type LD contribution. The intermediate amplitude for the process B_{s} --> ϕγis compared with the corresponding one obtained by a different approach based on the interaction of the virtual charm quark loop with soft gluons \cite{Ruckl}. Both amplitudes are found to agree within 10 %. Further the influence on the branching ratio B(B_{s} --> γγ)_{SD+LD_{O7}} from inclusive b --> s ψis estimated as less than 1 %.