arXiv subjects

A. T. Olgun

Publications and source records attributed to A. T. Olgun.

8 recordsLinked to original sources

arXiv2026

Comprehensive analyses of rare $ Λ_b \rightarrow Λ\ell^+ \ell^-$, $Σ_b \rightarrow Σ\ell^+ \ell^-$ and $Ξ_b \rightarrow Ξ\ell^+ \ell^-$ decays in the 2HDM

We investigate rare special dileptonic decays of $ Λ_b$, $Σ_b$ and $Ξ_b $ baryons in the Standard Model and context of the general Two-Higgs-Doublet Model with Type III. Specifically, we consider the decays $ Λ_b \rightarrow Λ\ell^+ \ell^-$, $Σ_b \rightarrow Σ\ell^+ \ell^-$ and $Ξ_b \rightarrow Ξ\ell^+ \ell^-$, where $\ell$ represents $μ$ or $τ$ lepton. By studying these rare decays, we aim to assess the impact of the Two-Higgs-Doublet Model with Type III on various observables, such as the differential decay width, the total decay width, the differential branching ratio, total branching ratio, and lepton forward-backward asymmetries using the decay amplitude and the transition matrix elements in terms of form factors calculated via light cone QCD in full theory. We compare our results to those of the Standard Model, as well as existing lattice QCD predictions and experimental data, to assess the agreement and viability of the Two-Higgs-Doublet Model with Type III. Furthermore, we highlight the potential for experimental investigations of these decay channels in the near future. The soon-to-be updated LHCb and/or Belle II detectors, renowned for their capabilities in studying rare decays, present excellent opportunities for probing the predicted branching ratios.

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arXiv2020

Effects of vector leptoquarks on $ Λ_b \rightarrow Λ_c~\ell ~ \overlineν_\ell$ decay

Experimental data on $ R(D^{(*)}) $, $ R(K^{(*)}) $ and $ R(J/ψ) $, provided by different collaborations, show sizable deviations from the SM predictions. To describe these anomalies many new physics scenarios have been proposed. One of them is leptoquark model with introducing the vector and scalar leptoquarks coupling simultaneously to the quarks and leptons. To look for similar possible anomalies in baryonic sector, we investigate the effects of a vector leptoquark $U_3 (3,3, \frac{2}{3})$ on various physical quantities related to the tree-level $ Λ_b \rightarrow Λ_c \ell ~ \overlineν_\ell$ decays ($ \ell=μ, ~τ$), which proceed via $ b \rightarrow c~\ell ~ \overlineν_\ell$ transitions at quark level. We calculate the differential branching ratio, forward-backward asymmetry and longitudinal polarizations of lepton and $Λ_{c}$ baryon at $ μ$ and $ τ$ lepton channels in leptoquark model and compare their behavior with respect to $ q^2 $ with the predictions of the standard model (SM). In the calculations we use the form factors calculated in full QCD as the main inputs and take into account all the errors coming from the form factors and model parameters. It is observed that ........

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arXiv2017

Impact of scalar leptoquarks on heavy baryonic decays

We present a study on the impact of scalar leptoquarks on the semileptonic decays of $ Λ_b$, $Σ_b $ and $Ξ_b $. To this end, we calculate the differential branching ratio and lepton forward-backward asymmetry defining the processes $ Λ_b \rightarrow Λ\ell^+ \ell^-$, $Σ_b \rightarrow Σ\ell^+ \ell^-$ and $Ξ_b \rightarrow Ξ\ell^+ \ell^-$, with $\ell$ being $μ$ or $τ$, using the form factors calculated via light cone QCD in full theory. In calculations, the errors of form factors are taken into account. We compare the results obtained in leptoquark model with those of the standard model as well as the existing lattice QCD predictions and experimental data.

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arXiv2015

Comparative analysis of the $Λ_b \rightarrow Λ\ell^+ \ell^-$ decay in the SM, SUSY and RS model with custodial protection

We comparatively analyze the rare $Λ_b\rightarrow Λ\ell^+ \ell^-$ channel in standard model, supersymmetry and Randall-Sundrum model with custodial protection (RS$_c$). Using the parametrization of the matrix elements entering the low energy effective Hamiltonian in terms of form factors, we calculate the corresponding differential decay width and lepton forward-backward asymmetry in these models. We compare the results obtained with the most recent data from LHCb as well as lattice QCD results on the considered quantities. It is obtained that the standard model, with the form factors calculated in light-cone QCD sum rules, can not reproduce some experimental data on the physical quantities under consideration but the supersymmetry can do it. The RS$_c$ model predictions are roughly the same as the standard model and there are no considerable differences between the predictions of these two models. In the case of differential decay rate, the data in the range $4 $ GeV$^2/$c$^4\leq$ $q^2 \leq 6$ GeV$^2/$c$^4$ can not be described by any of the considered models.

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arXiv2013

Analysis of the semileptonic $Λ_b\rightarrow Λ\ell^+ \ell^-$ transition in topcolor-assisted technicolor (TC2) model

We comparatively analyze the flavor changing neutral current process of the $Λ_b \rightarrow Λ\ell^+ \ell^-$ in the standard model as well as topcolor-assisted technicolor model using the form factors calculated via light cone QCD sum rules in full theory. In particular, we calculate the decay width, branching ratio and lepton forward-backward asymmetry related to this decay channel. We compare the results of the topcolor-assisted technicolor model with those of the standard model and debate how the results of the topcolor-assisted technicolor model depart from the standard model predictions. We also compare our results on the differential branching ratio with recent experimental data provided by CDF and LHCb Collaborations.

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arXiv2013

Analysis of the radiative $Λ_b\rightarrow Λγ$ transition in SM and scenarios with one or two universal extra dimensions

We investigate the radiative process of the $Λ_b\rightarrow Λγ$ in the standard model as well as models with one or two compact universal extra dimensions. Using the form factors entered to the low energy matrix elements, calculated via light cone QCD in full theory, we calculate the total decay width and branching ratio of this decay channel. We compare the results of the extra dimensional models with those of the standard model on the considered physical quantities and look for the deviations of the results from the standard model predictions at different values of the compactification scale (1/R).

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arXiv2012

Comparative analysis of the semileptonic $Λ_b \rightarrow Λ\ell^+ \ell^-$ transition in SM and different SUSY scenarios using form factors from full QCD

We work out the semileptonic $Λ_b\rightarrow Λ\ell^+ \ell^-$ transition in standard as well as different supersymmetric models. In particular, considering the parametrization of the matrix elements entered the low energy effective Hamiltonian in terms of form factors in full QCD, we calculate the amplitude and differential decay rate responsible for this decay channel in supersymmetric models. We then use the form factors calculated via light cone QCD sum rules in full theory to analyze the differential branching ratio and lepton forward-backward asymmetry of this decay channel in different supersymmetric models and compare the obtained results with those of the standard model. We also discuss how the results of different supersymmetric models deviate from the standard model predictions and which SUSY scenarios are favored.

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arXiv2012

Constraint on compactification scale via recently observed baryonic $Λ_b\rightarrow Λ\ell^+ \ell^-$ channel and analysis of the $Σ_b \rightarrow Σ\ell^+ \ell^-$ transition in SM and UED scenario

We obtain a lower limit on the compactification scale of extra dimension via comparison of the branching ratio in the baryonic $Λ_b\rightarrow Λμ^+ μ^-$ decay channel recently measured by CDF collaboration and our previous theoretical study. We also use the newly available form factors calculated via light cone QCD sum rules in full theory to analyze the flavour changing neutral current process of the $Σ_b \rightarrow Σ\ell^+ \ell^-$ in universal extra dimension scenario in the presence of a single extra compact dimension. We calculate various physical quantities like branching ratio, forward-backward asymmetry, baryon polarizations and double lepton polarization asymmetries defining the decay channel under consideration. We also compare the obtained predictions with those of the standard model.

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