arXiv subjects
Publications and source records attributed to M. Savci.
The $Ξ_Q^\prime$-$Ξ_Q$ transition magnetic moments are calculated in framework of the light cone QCD sum rules method (LCSR). The values of the transition magnetic moments obtained are compared with the predictions of the other theoretical approaches.
The form factors, as well as the helicity amplitudes for the $γ^\ast N \to N(1535)$ transition are calculated in framework of the QCD light cone sum rules. The contamination coming from diagonal transition is eliminated by considering combinations of the sum rules corresponding to different Lorentz structures. Similar procedure is applied for determination of the residue and mass of the negative parity baryon. Comparison of our predictions on the helicity amplitudes with the existing theoretical and experimental results is also presented.
The magnetic dipole G_M(Q^2), electric quadrupole G_E(Q^2), and Coulomb quadrupole G_C(Q^2) form factors, describing the spin-3/2 to spin-1/2 electromagnetic transitions, are investigated within the light cone QCD sum rules. The Q^2 dependence of these form factors, as well as ratios of electric quadrupole and Coulomb quadrupole form factors to the magnetic dipole form factors are studied. We also compare our results on the magnetic dipole form factor with the prediction of the covariant spectator quark model.
The $γ^\ast Λ\to Σ^0$ transition form factors are investigated within the light--cone QCD sum rules method. Using the most general form of the interpolating current of $Σ^0$ baryon and the distribution amplitudes of $Λ$ baryon we calculate the $Q^2$ dependence of the electromagnetic form factors. Our result are compared with the predictions of the covariant spectator quark model.
The electromagnetic form factors of octet baryons are estimated within light cone QCD sum rules method, using the most general form of the interpolating current for baryons. A comparison of our predictions on the magnetic dipole and electric form factors with the results of other approaches is performed.
The masses and residues of the spin--3/2 doubly heavy baryons are calculated within the QCD sum rules method. A comparison of our predictions with those existing in the literature is also made.
We calculate the masses and residues of the triply heavy spin--1/2 baryons using the most general form of their interpolating currents within the QCD sum rules method. We compare the obtained results with the existing theoretical predictions in the literature.
We calculate the mass and residue of the heavy spin--1/2 baryons containing two heavy b or c quarks in the framework of QCD sum rules. We use the most general form of the interpolating current in its symmetric and anti-symmetric forms with respect to the exchange of heavy quarks, to calculate the two-point correlation functions describing the baryons under consideration. A comparison of the obtained results with existing predictions from various approaches is also made.
We calculate the mixing angles between the spin--1/2, $Ξ_{bc}$--$Ξ^\prime_{bc}$ and $Ω_{bc}$--$Ω^\prime_{bc}$ states of doubly heavy baryons within the QCD sum rules method. It is found that the mixing angles are large and have the values $φ_{Ξ_{bc}} = 16^0 \pm 5^0$ and $φ_{Ω_{bc}} = 18^0 \pm 6^0$, respectively. The mixing angles are slightly smaller compared to the predictions of the non--relativistic quark model, $φ_{Ξ_{bc}} = 25.5^0$ and $φ_{Ω_{bc}} = 25.9^0$.
Possible manifestation of the family non-universal Z' boson effects in lepton polarization in rare, exclusive baryonic "Lambda_b -> Lambda l+l-" decay is examined. It is observed that the double lepton polarizations P_TT and P_NN are sensitive to the Z' contribution. Moreover, it is found that the zero position of the polarized forward-backward asymmetry A_FB^LL is shifted to the left compared to the standard model prediction. Therefore, determination of the zero value of A_FB^LL is quite an efficient tool for establishing new Z' boson, but also in discriminating various scenarios of the considered family non-universal Z' model.
We perform a comprehensive analysis of the rare "Lambda_b -> Lambda l+ l-" decay in the framework of family non-universal Z' model. It is shown that Z' gives considerable contribution to the decay width. Zero positions of the forward-backward asymmetry and alpha_theta parameter are shifted to the left compared to the Standard Model result. The obtained results could be tested in near future at LHC-b.
The exclusive (B -> K_2 l^+ l^-) decay is studied using the most general, model independent four-fermion interaction. The sensitivity of the ratio of the decay widths when K_2 meson is longitudinally and transversally polarized, the forward-backward asymmetry and longitudinal polarization of the final lepton on the new Wilson coefficients is studied. It is found that these quantities are very useful for establishing new physics beyond the Standard Model.
The strong coupling constants among members of the heavy spin--3/2 baryons containing single heavy quark with light pseudoscalar mesons are calculated in the framework of the light cone QCD sum rules. Using symmetry arguments, the structure independent relations among different correlation functions are obtained. It is shown that all possible transitions can be described in terms of one universal invariant function whose explicit expression is Lorenz structure dependent.
Using the calculated values of the strong coupling constants of the heavy sextet spin-3/2 baryons to sextet and antitriplet heavy spin-1/2 baryons with light mesons within the light cone QCD sum rules method, and vector meson dominance assumption, the radiative decay widths are calculated. These widths are compared with the "direct" radiative decay widths predicted in the framework of the light cone QCD sum rules.
Using the most general form of the nucleon interpolating current, we calculate the tensor form factors of the nucleon within light cone QCD sum rules. A comparison of our results on tensor form factors with those of the chiral--soliton model and lattice QCD is given.
All transitions among the heavy spin--3/2 sextet baryons with participation of the light vector mesons $(B_Q^* B_Q V)$ are investigated in the framework of the light cone sum rules. These vertices are described by four coupling constants. The corresponding sum rules are derived for each coupling constant. It is shown that the correlation functions of different transitions can be described by only one invariant function.
The heavy spin--3/2 baryon--heavy spin--1/2 baryon vertices with light vector mesons are studied within the light cone QCD sum rules method. These vertices are parametrized in terms of three coupling constants. These couplings are calculated for all possible transitions. It is shown that correlation functions for these transitions are described by only one invariant function for every Lorenz structure. The obtained relations between the correlation functions of the different transitions are structure independent while explicit expressions of invariant functions depend on the Lorenz structure.
The strong coupling constants of light pseudoscalar mesons with spin--3/2 and spin--1/2 heavy baryons are calculated in the framework of light cone QCD sum rules. It is shown that each class of transitions among members of the sextet spin--3/2 to sextet spin--1/2 baryons and that of the sextet spin--3/2 to spin--1/2 anti--triplet baryons is described by only one invariant function. We also estimate the widths of kinematically allowed transitions. Our results on decay widths are in good agreement with the existing experimental data, as well as predictions of other nonperturbative approaches.