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In the $\rm SU(3)_F$ symmetry limit, using two- and three-particle distribution amplitudes of $B^{\pm}$-meson for $B_s$, the transition form factors of semileptonic $B_{s}\to K_{0}^*(1430)$ decays are calculated in the framework of the light-cone sum rules. The two-particle distribution amplitudes, $\varphi_{_{+}}(\omega)$ and $\varphi_{_{-}}(\omega)$ have the most important contribution in estimation of the form factors $f_{+}(q^2)$, $f_{-}(q^2)$ and $f_{T}(q^2)$. The knowledge of the behavior of $\varphi_{_+}(\omega)$ is still rather limited. Therefore, we consider three different parametrizations for the shapes of $\varphi_{_+}(\omega)$ that are derived from the phenomenological models. Using the form factors $f_{+}$, $f_{-}$ and $f_{T}$, the semileptonic $B_s \to K_0^*(1430) l \bar{\nu_{l}}$ and $B_s \to K_0^*(1430) l \bar{l}/\nu \bar{\nu}$, $l=e, \mu, \tau$ decays are analyzed. The branching fractions for the aforementioned decays, in addition the longitudinal lepton polarization asymmetries are calculated. A comparison between our results with predictions of other approaches is provided., Comment: 17 pages, 10 figures

We investigate the strong coupling constants of $D D A$, $D^{*}D^{*}A$ and $D^{*} D A$ vertices in the framework of the light-cone QCD sum rules, where $A$ is an axial vector meson such as $a_1, b_1, K_{1A}, K_{1B}, K_1(1270)$ and $K_1(1400)$. Using the strong coupling constants of $D_s D K_1$, $D_s^* D K_1$ and $D_s^* D^* K_1$ vertices for $K_1(1270)$ and $K_1(1400)$ mesons, we evaluated the branching ratios of the non-leptonic decays $B^0\to {K}_{1}^{+}(1270,1400) ��^-$. Our results for the branching ratios of these decays are a good agreement with the experimental values., 15 pages, 7 figures

In this work, the transition form factors are calculated for the semileptonic $D_{(s)} \to A \ell^+ ��$ where $A=a_{1}, b_{1}, K_{1}(1270,1400)$, i.e., $D^{+} \to a^{0}_{1} (b^{0}_{1}, K^{0}_{1}) \ell^+ ��$, $D^{0} \to a^{-}_{1} (b^{-}_{1}) \ell^+ ��$, and $D^{+}_{s}\to K^{0}_{1} \ell^+ ��$ in the frame work of the light-cone QCD sum rules (LCSR) approach up to the twist-3 distribution amplitudes (DAs). Since the masses of these axial vector mesons are comparable to the charm quark mass, we keep out in our calculations all terms including ${m_{A}}/{m_c}$ in expansion of two--parton DAs. Branching ratio values are estimated for the semileptonic $D_{(s)} \to A \ell ��$ and nonleptonic $D\to K_1 (1270,1400) ��$ decays. A comparison is also made between our results and predictions of other methods and the existing experimental values., 17 pages, 4 figures

In this study, the coupling constant of $D^*_sD^*K^*$ and $D_{s1}D_1K^*$ vertices were determined within the three-point Quantum chromodynamics sum rules method with and without consideration of the $SU_{f}(3)$ symmetry. The coupling constants were calculated for off-shell charm and K$^*$ cases. Considering the non-perturbative effect of the correlation function, as the most important contribution, the quark-quark, quark-gluon, and gluon-gluon condensate corrections were estimated and were compared with other predictive methods., Comment: 12 pages, 5 figures

In this paper, the strong form factors and coupling constants of $D_sDK^*$ and $D_sD^*K^*$ vertices are investigated within the three-point QCD sum rules method with and without the $SU_{f}(3)$ symmetry. In this calculation, the contributions of the quark-quark, quark-gluon, and gluon-gluon condensate corrections are considered. As an example of specific application of these coupling constants, the branching ratio of the hadronic decay $B^+\to {K^*}^0 ��^+$ is analyzed based on the one-particle-exchange which is one of the phenomenological models. In this model, $B$ decays into a $D_s D^*$ intermediate state, and then these two particles exchange a $D (D^*)$ producing the final $K^*$ and $��$ mesons. In order to compute the effect of these interactions, the $D_s D K^*$ and $D_s D^* K^*$ form factors are needed., 14 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:1509.01715

The light-front distribution amplitudes (LFDAs) and the decay constant of the $K $ pseudoscalar meson are extracted within the framework of the AdS/QCD correspondence. For the LFDAs calculation, we consider a momentum-dependent (dynamical) helicity wave function which contains the dynamical spin effects. We use the LFDAs to predict the transition form factors of the semileptonic $B\to K \ell^{+}\ell^{-}$ decay. With the help of these form factors, the differential branching ratio of the $B\to K\, ��^+ ��^-$ on $q^2$ is plotted. A comparison is made between our prediction in AdS/QCD and the results obtained from two models including the light-cons sum rules (LCSR) and lattice QCD as well as the experimental values., 11 pages, 6 figures

The $B\to a_1 \ell^+ \ell^-$ decays occur by the electroweak penguin and box diagrams which can be performed through the flavor changing neutral current (FCNC). We calculate the form factors of the FCNC $B \to a_1$ transitions in the light--cone sum rules approach, up to twist--4 distribution amplitudes of the axial vector meson $a_1$. Forward--backward asymmetry, as well as branching ratios of $B\to a_1\ell^{+}\ell^{-}$, and $B\to a_1 \gamma$ decays are considered. A comparison is also made between our results and the predictions of other methods., Comment: 20 pages, 6 figures

The semileptonic $B_s (B) \to K_2^*(a_2, f_2) \ell\nu$, $\ell=\tau, \mu$ transitions are investigated in the frame work of the three-point QCD sum rules. Considering the quark condensate contributions, the relevant form factors of these transitions are estimated. The branching ratios of these channel modes are also calculated and compared with the obtained data for other approaches., Comment: 16 pages, 5 figures

Taking into account the contributions of the quark-quark, quark-gluon, and gluon-gluon condensate corrections, the strong form factors and coupling constants of $D^*_{s0}D^*_0K^*$, $D_sDK^*$, $D^*_sD^*K^*$, $D_{s1}D_1K^*$, $D_sD^*K^*$, and $D_{s0}D_1K^*$ vertices are investigated within the three-point QCD sum rules method, without and with the $SU_{f}(3)$ symmetry., 23 pages, 5 figures

We investigate the structure of the $D_{1}^0(2420[2430]) (J^P=1^+)$ mesons via analyzing the semileptonic $B_{c}\to D_{1}^0 l\nu$ transition in the frame work of the three--point QCD sum rules and the heavy quark effective theory. We consider the $D_{1}^0$ meson in three ways; the pure $|c\bar{u}\rangle$ state, a mixture of two $|^3P_1\rangle$ and $|^1P_1\rangle$ states with a mixing angle $\theta$ and a combination of two mentioned states with mixing angle $\theta=35.3^\circ$ in the heavy quark limit. Taking into account the gluon condensate contributions, the relevant form factors are obtained for the three above conditions. These form factors are numerically calculated for $|c\bar{u}\rangle$ and the heavy quark limit cases. The obtained results for the form factors are used to evaluate the decay rates and the branching ratios. Also for mixed states, all of the mentioned physical quantities are plotted with respect to the unknown mixing angle $\theta$., Comment: arXiv admin note: substantial text overlap with arXiv:0907.4773

We analyze the semileptonic $B \to a_1 \ell^+\ell^-$, $\ell=\tau, \mu, e$ transitions in the frame work of the three-point QCD sum rules in the standard model. These rare decays governed by flavor-changing neutral current transition of $b \to d$. Considering the quark condensate contributions, the relevant form factors as well as the branching fractions of these transitions are calculated.

Probing the $\bar ss$ content of the $��$ and $��'$ mesons and considering mixing between these states as well as gluonic contributions, the form factors responsible for semileptonic $D_s \to (��, ��') l ��$ transitions are calculated via light cone QCD sum rules. Corresponding branching fractions and their ratio for different mixing angles are also obtained. Our results are in a good consistency with experimental data as well as predictions of other nonperturbative approaches., 13 Pages, 2 Figure and 4 Tables

We investigate the structure of the $D_{s1}(2460,2536) (J^P=1^+)$ mesons via analyzing the semileptonic $B_{c}\to D_{s1}l^+l^-$, $l=��, ��, e$ and $B_{c}\to D_{s1}��\bar��$ transitions in the framework of the three--point QCD sum rules. We consider the $D_{s1}$ meson in two ways, the pure $|c\bar{s}>$ state and then as a mixture of two $|^3P_1>$ and $|^1P_1>$ states. Such type rare transitions take place at loop level by electroweak penguin and weak box diagrams in the standard model via the flavor changing neutral current transition of $b \to s$. The relevant form factors are calculated taking into account the gluon condensate contributions. These form factors are numerically obtained for $|c\bar s>$ case and plotted in terms of the unknown mixing angle $��_s$, when the $D_{s1}$ meson are considered as mixture of two $|^3P_1>$ and $|^1P_1>$ states. The obtained results for the form factors are used to evaluate the decay rates and branching ratios. Any future experimental measurement on these form factors as well as decay rates and branching fractions and their comparison with the obtained results in the present work can give considerable information about the structure of this meson and the mixing angle $��_s$., 33 Pages, 11 Figures and 5 Tables

Considering the gluon condensate corrections, the form factors relevant to the semileptonic rare $B_c \rar D,D_s(J^{P}=0^{-}) l^{+}l^{-}$ with $l=��,��,e$ and $B_c \rar D,D_s(J^{P}=0^{-})��\bar��$ transitions are calculated in the framework of the three point QCD sum rules. The heavy quark effective theory limit of the form factors are computed. The branching fraction of these decays are also evaluated and compared with the predictions of the relativistic constituent quark model. Analyzing of such type transitions could give useful information about the strong interactions inside the pseudoscalar $D_{s}$ meson and its structure., 32 Pages, 8 Figures and 6 Tables

Taking into account the gluon condensate contributions, the form factors of the semileptonic $B_c^- \to D^{*0}\ell��$ transition with $l=��, e$ are calculated in the framework of the three point QCD sum rules. The heavy quark effective theory limit of the form factors are also computed. The relevant total decay width as well as the branching ratio are evaluated and compared with the predictions of the other non-perturbative approaches., 27 Pages, 4 Figures and 4 Tables

Taking into account the gluon correction contributions to the correlation function, the form factors relevant to the rare $B_c \rar X ��\bar��$ decays are calculated in the framework of the three point QCD sum rules, where $X$ stands for axial vector particle, $AV(D_{s1})$, and vector particles, $V(D^*,D^*_s)$. The total decay width as well as the branching ratio of these decays are evaluated using the $q^2$ dependent expressions of the form factors. A comparison of our results with the predictions of the relativistic constituent quark model is presented., 21 Pages, 2 Figures and 5 Tables

We analyze the semileptonic $D_{q}\to K_1 \ell��$ transition with $q=u, d, s$, in the framework of the three--point QCD sum rules and the nonleptonic $D\to K_1 ��$ decay within the QCD factorization approach. We study $D_{q}$ to $K_1(1270)$ and $K_1(1400)$ transition form factors by separating the mixture of the $K_1(1270)$ and $K_1(1400)$ states. Using the transition form factors of the $D\to K_1 $, we analyze the nonleptonic $D\to K_1 ��$ decay. We also present the decay amplitude and decay width of these decays in terms of the transition form factors. The branching ratios of these channel modes are also calculated at different values of the mixing angle $��_{K_1}$ and compared with the existing experimental data for the nonleptonic case., 28 Pages, 20 Figures and 9 Tables