arXiv subjects
Publications and source records attributed to H. Sundu.
The strong coupling form factors related to the strong vertices of the positive and negative parity nucleons with the heavy $Λ_{b[c]}[Σ_{b[c]}]$ baryons and heavy $B^*[D^*]$ vector mesons are calculated using a three-point correlation function. Using the values of the form factors at $Q^2=-m^2_{meson}$ we compute the strong coupling constants among the participating particles.
We investigate the $N^{\ast}(1535)\rightarrow Nγ$ transition in the framework of light cone QCD sum rules. In particular, using the most general form of the interpolating current for the nucleon as well as the distribution amplitudes of the photon, we calculate two transition form factors responsible for this channel and use them to evaluate the decay width and branching ratio of the transition under consideration. The result obtained for the branching fraction is in a good consistency with the experimental data.
The thermal properties of $f_{2}(1270)$, $a_{2}(1320)$ and $K_2^*(1430)$ light tensor mesons are investigated in the framework of QCD sum rules at finite temperature. In particular, the masses and decay constants of the light tensor mesons are calculated taking into account the new operators appearing at finite temperature. The numerical results show that at the point which the temperature-dependent continuum threshold vanishes, the decay constants decrease with amount of $(70-85)\%$ compared to their vacuum values, while the masses diminish about $(60-72)\%$ depending on the kinds of the mesons under consideration. The results obtained at zero temperature are in good consistency with the experimental data as well as existing theoretical predictions.
We analyze the semileptonic $ B_{s} \rightarrow D_{s2}^{*}(2573)\ell\bar{ν}_{\ell}$ transition, where $\ell=τ,~μ$ or $e$, within the standard model. We apply the QCD sum rule approach to calculate the transition form factors entering the low energy Hamiltonian defining this channel. The fit functions of the form factors are used to estimate the total decay widths and branching fractions in all lepton channels. The orders of branching ratios indicate that this transition is accessible at LHCb in near future.
We study the semileptonic tree-level $B \rightarrow \bar{D}$ transition in the framework of QCD sum rules in nuclear medium. In particular, we calculate the in-medium form factors entering the transition matrix elements defining this decay channel. It is found that the interactions of the participating particles with the medium lead to a considerable suppression in the branching ratio compared to the vacuum.
In this study, we investigate the sensitivity of the masses and decay constants of the light $f_{2}(1270)$ and $a_{2}(1320)$ tensor mesons to the temperature using QCD sum rule approach. In our calculations, we take into account the additional operators appearing in operator product expansion at finite temperature. It is obtained that at deconfinement temperature the decay constants and masses decrease with amount of $6\%$ and $96\%$ compared to their vacuum values, respectively. Our results on the masses at zero temperature are consistent with the vacuum sum rules predictions as well as the experimental data.
We investigate the strong vertices among $Λ_b$, nucleon and $B$ meson as well as $Λ_c$, nucleon and $D$ meson in QCD. In particular, we calculate the strong coupling constants $g_{Λ_bNB}$ and $g_{Λ_cND}$ for different Dirac structures entered the calculations. In the case of $Λ_cND$ vertex, the result is compared with the only existing prediction obtained at $Q^2=0$.
We calculate the magnetic dipole and electric quadrupole moments associated with the radiative $Ω_{Q}^{*}\rightarrowΩ_{Q}γ$ and $Ξ_{Q}^{*}\rightarrowΞ^{\prime}_{Q}γ$ transitions with $Q=b$ or $c$ in the framework of light cone QCD sum rules. It is found that the corresponding quadrupole moments are negligibly small while the magnetic dipole moments are considerably large. A comparison of the results on the considered multipole moments as well as corresponding decay widths with the predictions of the vector dominance model is performed.
The strong $D_{2}^{*}(2460)^{0}\rightarrow D^+ π^- $ and $D_{s2}^{*}(2573)^{+}\rightarrow D^{+} K^{0}$ transitions are analyzed via three point QCD sum rules. First, we calculate the corresponding strong coupling constants $g_{D_2^*Dπ}$ and $g_{D_{s2}^*DK}$. Then, we use them to calculate the corresponding decay widths and branching ratios. Making use of the existing experimental data on the ratio of the decay width in the pseudoscaler $D$ channel to that of the vector $D^*$ channel, finally, we estimate the decay width and branching ratio of the strong $D_2^*(2460)^0 \rightarrow D^*(2010)^+π^-$ transition.
We calculate the shifts in decay constants of the pseudoscalar $B$ and $D$ mesons in nuclear medium in the frame work of QCD sum rules. We write those shifts in terms of the $B-N$ and $D-N$ scattering lengths and an extra phenomenological parameter entered to calculations. Computing an appreciate forward scattering correlation function, we derive the QCD sum rules for the $B-N$ and $D-N$ scattering lengths and the extra phenomenological parameter in terms of various operators in nuclear medium. We numerically find the values of the shifts in the decay constants compared to their vacuum values. Using the sum rules obtained, we also determine the shifts in the masses of these particles due to nuclear matter and compare the results obtained with the previous predictions in the literature.
We investigate the masses and decay constants of the heavy-light $D_2^*(2460)$ and $D_{s2}^*(2573)$ tensor mesons in the framework of thermal QCD sum rules. Taking into account the additional operators arising at finite temperature, we evaluate the Wilson expansion for the two-point correlation function associated with these mesons. We observe that the values of the masses and decay constants decrease considerably at near to the critical temperature. The decay constants attain roughly to $25\%$ of their values in vacuum, while the masses decrease about $39\%$ and $37\%$ in $D_2^*$ and $D_{s2}^*$ channels, respectively.
The mass and current coupling constant of the $D_{s2}^* (2573)$ charmed-strange meson is calculated in the framework of two-point QCD sum rule approach. Although the quantum numbers of this meson is not exactly known, its width and decay modes are consistent with $I(J^P)=0(2^+)$, which we consider to write the interpolating current used in our calculations. Replacing the light strange quark with up or down quark we also compare the results with those of $D_{2}^*$ charmed tensor meson and estimate the order of SU(3) flavor symmetry violation.
The strong coupling constants among mesons are very important quantities as they can provide useful information on the nature of strong interaction among hadrons as well as the QCD vacuum. In this article, we investigate the strong vertices of the $D^{\ast}_{s}D_{s} η^{(\prime)}$ and $B^{\ast}_{s}B_{s} η^{(\prime)}$ in the framework of the QCD sum rule approach choosing the $η$ or $D_{s} (B_{s})$ meson as an off-shell state. We obtain the results $g_{D_s^*D_sη}=(1.46\pm 0.30)GeV^{-1}$, $g_{D_s^*D_sη^{\prime}}=(0.74\pm 0.16)GeV^{-1}$, $g_{B_s^*B_sη}=(5.29\pm 1.06)GeV^{-1}$ and $g_{B_s^*B_sη^{\prime}}=(2.29\pm 0.48)GeV^{-1}$ for the strong coupling constants under consideration, which can be checked in future experiments.
We calculate the mass and decay constant of the $D_2^*(2460)$ tensor meson in the framework of QCD sum rules. The obtained result on the mass is compatible with the experimental data. Our prediction on the decay constant can be checked in experiment.
The transition form factors of the semileptonic $B \rightarrow D_2^*(2460)\ell\barν\,\,\,\,(\ell=τ,μ,e)$ decay channel are calculated within the framework of the three-point QCD sum rules. The fit functions of the form factors are then used to estimate the total decay width and branching ratio of this transition. The order of branching ratio shows that this channel can be detected at LHCb.
We calculate the transition form factors of the semileptonic $B_c\rightarrow χ_{c2} l \barν $ in the framework of QCD sum rules taking into account the two-gluon condensate corrections. Using the obtained results of form factors we estimate the decay widths and branching ratios related to this transition at all lepton channels. A comparison of the obtained results with the predictions of other non-perturbative approaches are also made. The orders of branching ratios for different lepton channels indicate that the $B_c\rightarrow χ_{c2} l \barν $ transition can be studied at LHC using the collected or future data.
Taking into account the two-gluon condensate contributions, the transition form factors enrolled to the low energy effective Hamiltonian describing the semileptonic $χ_{b0}\rightarrow B_{c}\ell\barν, (\ell=(e,μ,τ))$ decay channel are calculated within three-point QCD sum rules. The fit function of the form factors then are used to estimate the decay width of the decay mode under consideration.
Using the additional operators coming up at finite temperature, we calculate the masses and decay constants of the P wave heavy axial-vector χ_b1 and χ_c1 quarkonia in the framework of thermal QCD sum rules. In the calculations, we take into account the perturbative two loop order alpha_s corrections and nonperturbative effects up to the dimension four condensates. It is observed that the masses and decay constants almost remain unchanged with respect to the variation of the temperature up to T \simeq 100 MeV, however after this point, the decay constants decrease sharply and approach approximately to zero at critical temperature. The decreasing in values of the masses is also considerable after T \simeq 100 MeV .