Radiative transition of negative to positive parity nucleon

We investigate the $N^{\ast}(1535)\rightarrow N\gamma$ 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.Comment: A typo has been correcte

The strong ΛbNB\Lambda_bNB and ΛcND\Lambda_cND vertices

We investigate the strong vertices among $\Lambda_b$, nucleon and $B$ meson as well as $\Lambda_c$, nucleon and $D$ meson in QCD. In particular, we calculate the strong coupling constants $g_{\Lambda_bNB}$ and $g_{\Lambda_cND}$ for different Dirac structures entered the calculations. In the case of $\Lambda_cND$ vertex, the result is compared with the only existing prediction obtained at $Q^2=0$.Comment: 12 Pages, 3 Figures and 4 Table

Positive and negative parity hyperons in nuclear medium

The effects of nuclear medium on the residue, mass and self energy of the positive and negative parity $\Sigma$, $\Lambda$ and $\Xi$ hyperons are investigated using the QCD sum rule method. In the calculations, the general interpolating currents of hyperons with an arbitrary mixing parameter are used. We compare the results obtained in medium with those of the vacuum and calculate the shifts in the corresponding parameters. It is found that the shifts on the residues in nuclear matter are over all positive for both the positive and negative parity hyperons, except for the positive parity $\Sigma$ hyperon that the shift is negative. The shifts on the masses of these baryons are obtained to be negative. The shifts on the residues and masses of negative parity states are large compared to those of positive parities. The maximum shift belongs to the residue of the negative parity $\Lambda$ hyperon. The vector self-energies gained by the positive parity baryons are large compared to the negative parities' vector self-energies. The maximum value of the vector self-energy belongs to the positive parity $\Sigma$ hyperon. The numerical values are compared with the existing predictions in the literature.Comment: 20 Pages, 9 Figures and 7 Table

Strong couplings of negative and positive parity nucleons to the heavy baryons and mesons

The strong coupling form factors related to the strong vertices of the positive and negative parity nucleons with the heavy $\Lambda_{b[c]}[\Sigma_{b[c]}]$ 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.Comment: 12 Pages and 7 Table

Investigation of the semileptonic transition of the BB into the orbitally excited charmed tensor meson

The transition form factors of the semileptonic $B \rightarrow D_2^*(2460)\ell\bar{\nu}\,\,\,\,(\ell=\tau,\mu,e)$ 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.Comment: 15 Pages, 4 Figures and 5 Table

On the strong coupling N(∗)N(∗)πN^{(*)}N^{(*)}\pi

We study the strong vertices $N^*N\pi$, $N^*N^*\pi$ and $NN\pi$ in QCD, where $N^*$ denotes the negative parity $N (1535)$ state. We use the most general form of the interpolating currents to calculate the corresponding strong coupling constants. It is obtained that the coupling associated to $N^*N\pi$ vertex is strongly suppressed compared to those related to two other vertices. The strong coupling corresponding to $N^*N^*\pi$ is obtained to be roughly half of that of $NN\pi$ vertex. We compare the obtained results on $N^*N\pi$ and $NN\pi$ vertices with the existing predictions of other theoretical studies as well as those extracted from the experimental data.Comment: 15 Pages, 4 Figures and 3 Table

More about the BB and DD mesons in nuclear matter

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.Comment: 16 Pages, 4 Figures and 3 Table