arXiv subjects

Gursevil Turan

Publications and source records attributed to Gursevil Turan.

12 recordsLinked to original sources

arXiv2005

The effects of non-standard Z couplings on the lepton polarizations in B_s to γ\ell^+ \ell^- decays

The fact that the measured B to ππ, πK branching ratios exhibit puzzling patterns has received a lot of attention in the literature and motivated the formulation of a series of new physics scenarios with enhanced Z-penguins. In this work, we analyze the effect of such an enhancement on the lepton polarization asymmetries of B_s to γ\ell^+ \ell^- decays by applying the results of a specific scenario for the solution of ``B to πK puzzle''.

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arXiv2005

CP violation in polarized B-> pi ell+ ell- and B-> rho ell+ ell- decays

We study the decay rate and the CP violating asymmetry of the exclusive B-> pi ell+ ell- and B-> rho ell+ ell- decays in the case where one of the final leptons is polarized. We calculate the contributions coming from the individual polarization states in order to identify a so-called wrong sign decay, which is a decay with a given polarization, whose width and CP asymmetry are smaller as compared to the unpolarized one. The results are presented for electron and tau leptons. We observe that in particular decay channels, one can identify a wrong sign decay which is more sensitive to new physics beyond the Standard Model.

hep-ph↗

arXiv2004

Standard Model CP violation in B->X_d \ell^+\ell^- decays

We investigate the CP violating asymmetry, the forward backward asymmetry and the CP violating asymmetry in the forward-backward asymmetry for the inclusive B->X_d \ell^+\ell^- decays for the \ell=e,μτchannels in the standard model. It is observed that these asymmetries are quite sizable and B->X_d \ell^+\ell^- decays seem promising for investigating CP violation.

hep-ph↗

arXiv2003

The analysis of $B_{d} -> (η, η^{\prime}) \ell^+ \ell^-$ decays in the standard model

We study the differential branching ratio, branching ratio and the CP-violating asymmetry for the exclusive $B_{d}->(η, η^{\prime}) \ell^+ \ell^-$ decays in the standard model. We deduce the $B_{d}->(η, η^{\prime})$ form factors from the form factors of $B -> π$ available in the literature, by using the $SU(3)_F$ symmetry. We observe that these decay modes, which are within the reach of forthcoming B-factories, are very promising to observe CP-violation.

hep-ph↗

arXiv2002

Rare B_s -> γν\barν decay with polarized photon and new physics effects

Using the most general, model independent effective Hamiltonian, the rare B_s ->γν\barν decay with polarized photon is studied. The sensitivity of the branching ratio and photon polarization to the new Wilson coefficients are investigated. It is shown that these physical observables are sensitive to the vector and tensor type interactions, which would be useful in search of new physics.

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arXiv2002

CP violation in the radiative dileptonic B-meson decays

We investigate the CP violating asymmetry, the forward backward asymmetry and the CP violating asymmetry in the forward-backward asymmetry for the radiative dileptonic B-meson decays $B_{d}\to γ\ell^+ \ell^-$ for the $\ell= e, μ, τ$ channels. It is observed that these asymmetries are quite sizable and $B_{d}\to γ\ell^+ \ell^-$ decays seem promising for investigating CP violation.

hep-ph↗

arXiv2002

The exclusive $B_s->ϕ\ell^+ \ell^-$ decay in the two Higgs doublet models

We study the differential branching ratio, branching ratio and the forward-backward asymmetry for the exclusive $B_s->ϕ\ell^+ \ell^-$ decay in the two Higgs doublet model. We analyze the dependencies of these quantities on the model parameters and show that these observables are highly sensitive to new physics and hence may provide powerful probe of the SM and beyond.

hep-ph↗

arXiv2002

The exclusive $B -> (K, K^*) \ell^+ \ell^-$ decays in a CP softly broken two Higgs doublet model

We study the differential branching ratio, forward-backward asymmetry, CP-violating asymmetry, CP-violating asymmetry in the forward-backward asymmetry and polarization asymmetries in the $B -> K \ell^+ \ell^-$ and $B -> K^* \ell^+ \ell^-$ decays in the context of a CP softly broken two Higgs doublet model. We analyze the dependencies of these observables on the model parameters by paying a special attention to the effects of neutral Higgs boson (NHB) exchanges and possible CP violating effects. We find that NHB effects are quite significant for both decays. A combined analysis of above-mentioned observables seems to be very promising as a testing ground for new physics beyond the SM, especially for the existence of the CP-violating phase in the theory.

hep-ph↗

arXiv2002

The exclusive $B\to π\ell^+ \ell^-$ and $B\to ρ\ell^+ \ell^-$ decays in the general two Higgs doublet model

We study the differential branching ratio, branching ratio and the forward-backward asymmetry for the exclusive $B \to π\ell^+ \ell^-$ and $B \to ρ\ell^+ \ell^-$ decays in the general two Higgs doublet model including the neutral Higgs boson effects. We analyze the dependencies of these quantities on the neutral Higgs boson contributions and the other model parameters. We observe that two Higgs doublet model with the neutral Higgs boson exchanges gives quite sizable contributions to these observables for both channels we consider. Since the neutral Higgs boson exchanges are the only source of the forward-backward asymmetry for $B \to πτ^+ τ^-$ decay, which is at the order of magnitude $1-10%$, measurement of this observable is promising to determine the neutral Higgs boson effects.

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arXiv2001

Radiative dileptonic decays of B-meson in the general two Higgs doublet model

We investigate the exclusive $B\to γ\ell^+ \ell^- $ decay in the general two Higgs doublet model (model III) including the neutral Higgs boson effects with an emphasis on possible CP-violating effects. For this decay, we analyse the dependencies of the forward-backward asymmetry of the lepton pair, $A_{FB}$, CP-violating asymmetry, $A_{CP}$, and the CP-violating asymmetry in forward-backward asymmetry, $A_{CP}(A_{FB})$, on the model parameters and also on the neutral Higgs boson effects. We have found that $A_{FB}\sim 10^{-1}, 10^{-2}$, $A_{CP}\sim 10^{-2}, 10^{-1}$ and $A_{CP}(A_{FB}) \sim 10^{-2}, 10^{-1}$ depending on the relative magnitude of the Yukawa couplings $\barξ_{N,tt}^{U}$ and $\barξ_{N,bb}^{D}$ in the model III. We also observe that these physical quantities are sensitive to the model parameters and neutral Higgs boson effects are quite sizable for some values of the coupling $\barξ_{N,ττ}^{D}$.

hep-ph↗

arXiv2001

$B\to τ^+ τ^- γ$ decay in the general two Higgs doublet model including the neutral Higgs boson effects

We investigate the differential branching ratio, branching ratio, differential forward-backward asymmetry, the forward-backward asymmetry of the lepton pair and the lepton polarization asymmetry of the exclusive $B\to τ^+ τ^- γ$ decay in the general two Higgs doublet model including the neutral Higgs boson effects. We analyse the dependencies of these quantities on the model parameters and also on the neutral Higgs boson effects. We found that they get considerable enhancement from the two Higgs doublet model compared to the standard model and neutral Higgs boson effects are quite sizable.

hep-ph↗

arXiv1996

Charm and Bottom Semileptonic Decays

We review the present status of theoretical attempts to calculate the semileptonic charm and bottom decays and then present a calculation of these decays in the light--front frame at the kinematic point $q^2=0$. This allows us to evaluate the form factors at the same value of $q^2$, even though the allowed kinematic ranges for charm and bottom decays are very different. Also, at this kinematic point the decay is given in terms of only one form factor $A_{0}(0)$. For the ratio of the decay rates given by the E653 collaboration we show that the determination of the ratio of the Cabibbo--Kobayashi--Maskawa (CKM) matrix elements is consistent with that obtained from the unitarity constraint. At present, though, the unitarity method still has greater accuracy. Since comparisons of the semileptonic decays into $ρ$ and either electrons or muons will be available soon from the E791 Fermilab experiment, we also look at the massive muon case. We show that for a range of $q^2$ the $SU(3)_F$ symmetry breaking is small even though the contributions of the various helicity amplitudes becomes more complicated. For $B$ decays, the decay $B \rightarrow K^{*} \ell \bar{\ell}$ at $q^2=0$ involves an extra form factor coming from the photon contribution and so is not amenable to the same kind of analysis, leaving only the decay $B \rightarrow K^{*}ν\barν$ as a possibility. As the mass of the decaying particle increases we note that the $SU(3)$ symmetry becomes badly broken at $q^2=0$.

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