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M. Bayar

Publications and source records attributed to M. Bayar.

49 records · Page 3Linked to original sources
arXiv2010

Flavor Changing Neutral Currents Transition of the $Σ_{Q}$ to Nucleon in Full QCD and Heavy Quark Effective Theory

The loop level flavor changing neutral currents transitions of the $Σ_{b}\to n l^+l^-$ and $Σ_{c}\to p l^+l^-$ are investigated in full QCD and heavy quark effective theory in the light cone QCD sum rules approach. Using the most general form of the interpolating current for $Σ_{Q}$, $Q=b$ or $c$, as members of the recently discovered sextet heavy baryons with spin 1/2 and containing one heavy quark, the transition form factors are calculated using two sets of input parameters entering the nucleon distribution amplitudes, namely, QCD sum rules and lattice QCD inputs. The obtained results are used to estimate the decay rates of the corresponding transitions. Since such type transitions occurred at loop level in the standard model, they can be considered as good candidates to search for the new physics effects beyond the SM.

hep-ph↗
arXiv2009

Semileptonic $Λ_{b,c}$ to Nucleon Transitions in Full QCD at Light Cone

The tree level semileptonic $Λ_{b}\to plν$ and $Λ_{c}\to nlν$ transitions are investigated using the light cone QCD sum rules approach in full theory. The spin--1/2, $Λ_{Q}$ baryon with $Q=b$ or $c$, is considered by the most general form of its interpolating current. The time ordering product of the initial and transition currents is expanded in terms of the nucleon distribution amplitudes with different twists. Considering two sets of independent input parameters entering to the nucleon wave functions, namely, QCD sum rules and Lattice QCD parameters, the related form factors and their heavy quark effective theory limits are calculated and compared with the existing predictions of other approaches. It is shown that our results satisfy the heavy quark symmetry relations for lattice input parameters and b case exactly and the maximum violation is for charm case and QCD sum rules input parameters. The obtained form factors are used to compute the transition rates both in full theory and heavy quark effective theory. A comparison of the results on decay rate of $Λ_{b}\to plν$ with those predicted by other phenomenological methods or the same method in heavy quark effective theory with different interpolating current and distribution amplitudes of the $Λ_{b}$ is also presented.

hep-ph↗
arXiv2009

Tree Level Semileptonic $Σ_{b}$ to Nucleon Decay in Light Cone QCD Sum Rules

Using the most general form of the interpolating current of the heavy spin 1/2, $Σ_{b}$ baryon and distribution amplitudes of the nucleon, the transition form factors of the semileptonic $Σ_{b}\to Nlν$ decay are calculated in the framework of light cone QCD sum rules. It is obtained that the form factors satisfy the heavy quark effective theory relations. The obtained results for the related form factors are used to estimate the decay rate of this transition.

hep-ph↗
arXiv2009

Semileptonic B_{c} to P-Wave Charmonia Transitions within QCD Sum Rules

The form factors of the semileptonic $B_c\to S(AV)\ellν$ $(\ell=τ, μ, e)$ transitions, where S and AV denote the scalar $X_{c0}$ and axial vector $(X_{c1}, h_{c})$ mesons, are calculated within the framework of the three-point QCD sum rules. The heavy quark effective theory limit of the form factors are also obtained and compared with the values of the original transition form factors. The results of form factors are used to estimate the total decay widths and branching ratios of these transitions. A comparison of our results on branching ratios with the predictions of other approaches is also presented.

hep-ph↗
arXiv2009

Analysis of Various Polarization Asymmetries In The Inclusive $b\to s \ell^+ \ell^-$ Decay In The Fourth-Generation Standard Model

In this study a systematical analysis of various polarization asymmetries in inclusive $b \rar s \ell^+ \ell^-$ decay in the standard model (SM) with four generation of quarks is carried out. We found that the various asymmetries are sensitive to the new mixing and quark masses for both of the $μ$ and $τ$ channels. Sizeable deviations from the SM values are obtained. Hence, $b \rar s \ell^+ \ell^-$ decay is a valuable tool for searching physics beyond the SM, especially in the indirect searches for the fourth-generation of quarks ($t', b')$.

hep-ph↗
arXiv2009

${Σ_{Q}Λ_{Q}π}$ Coupling Constant in Light Cone QCD Sum Rules

The strong coupling constants $g_{{Σ_{Q}Λ_{Q}π}}$ ($Q=b$ and $c$) are studied in the framework of the light cone QCD sum rules using the most general form of the baryonic currents. The predicted coupling constants are used to estimate the decay widths for the $Σ_{Q}\longrightarrowΛ_{Q}π$ decays which are compared with the predictions of the other approaches and existing experimental data.

hep-ph↗
arXiv2009

Asymmetry Parameter of the $K_{1} (1270, 1400)$ by Analyzing the $B\to K_{1}ν\barν$ Transition Form Factors within QCD

Separating the mixture of the $ K_{1}(1270)$ and $K_{1}(1400) $ states, the $B\to K_{1}(1270, 1400)ν\barν$ transition form factors are calculated in the three-point QCD sum rules approach. The longitudinal, transverse and total decay widths as well as the asymmetry parameter, characterizing the polarization of the axial $K_{1}(1270, 1400)$ and the branching ratio for these decays are evaluated.

hep-ph↗
arXiv2008

Semileptonic $B_{q}\to D^{\ast}_{q}lν$ $(q=s, d, u)$ transitions in QCD

The form factors relevant to $B_{q}\to D^{\ast}_{q}(J^{P}=1^{-})\ellν$ $(q=s, d, u)$ decays are calculated in the framework of the three point QCD sum rules approach. The heavy quark effective theory prediction of the form factors are obtained. The total decay width and branching ratio for these decays are also evaluated using the $q^2$ dependencies of these form factors.

hep-ph↗
arXiv2008

Semileptonic $B_{q}\to D^{\ast}_{q}lν$ $(q=s, d, u)$ Decays in QCD Sum Rules

The form factors relevant to $B_{q}\to D^{\ast}_{q}(J^{P}=1^{-}) ellν$ $(q=s, d, u)$ decays are calculated in the framework of the three point QCD sum rules approach. The heavy quark effective theory prediction of the form factors as well as $1/m_{b}$ corrections to those form factors are obtained. A comparison of the results for the ratio of form factors at zero recoil limit and other values of $q^{2}$ with the predictions of the subleading Isgur-Wise form factor application for $B\to D^{\ast}\ellν$ is presented. The total decay width and branching ratio for these decays are also evaluated using the $q^2$ dependencies of these form factors. The results are in good agreement with the constituent quark meson model and existing experimental data. The $q=s$ case can also be detected at LHC in the near future.

hep-ph↗
arXiv2008

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.

hep-ph↗