Light Mesons elm Form Factor and Running Coupling Effects

The pion and kaon electromagnetic form factors $F_{M}(Q^2)$ are calculated at the leading order of pQCD using the running coupling constant method. In computations dependence of the meson distribution amplitudes on the hard scale $Q^2$ is taken into account. The Borel transform and resummed expression for $F_{M}(Q^2)$ are found. The effect of the next-to-leading order term in expansion of $\alpha_{S}(\lambda Q^2)$ in terms of $\alpha_{S}(Q^2)$ on the pion form factor $F_{\pi}(Q^2)$ is discussed, comparison is made with the infrared matching scheme's result.Comment: 10 pages, 2 figures. Talk given at the Euroconference QCD98, Montpellier 2-8th July 1998, France; to appear in Proceeding

Strong Ds∗Dsη(′)D^{*}_sD_{s}\eta^{(\prime)} and Bs∗Bsη(′)B^{*}_sB_{s}\eta^{(\prime)} vertices from QCD light-cone sum rules

The strong $D^{*}_sD_{s}\eta^{(\prime)}$ and $B^{*}_sB_{s}\eta^{(\prime)}$ vertices are studied and the relevant couplings are calculated in the context of the light-cone QCD sum rule method with twist-4 accuracy by including the next-to-leading order corrections. In the analysis, both the quark and gluon components of the $\eta$ and $\eta^{\prime}$ mesons and the axial anomaly corrected higher twist distributions are included.Comment: 15 Pages and 6 Figure

Charmed partner of the exotic X(5568)X(5568) state and its properties

The mass, decay constant and width of a hypothetical charmed partner $X_c$ of the newly observed exotic $X_b(5568)$ state are calculated using a technique of QCD sum rule method. The $X_c=[su][\overline{c}\overline{d}]$ state with $J^{P}=0^{+}$ is described employing two types of the diquark-antidiquark interpolating currents. The evaluation of the mass $m_{X_c}$ and decay constant $f_{X_c}$ is carried out utilizing the two-point sum rule method by including vacuum condensates up to eight dimensions. The widths of the decay channels $X_c \to D_s^{-} \pi^{+}$ and $X_c \to D^{0} K^{0}$ are also found. To this end, the strong couplings $g_{X_{c}D_{s}\pi}$ and $g_{X_{c}D K}$ are computed by means of QCD sum rules on the light-cone and soft-meson approximation.Comment: 7 Pages, 2 Figures and 3 Table

Mass and decay constant of the newly observed exotic X(5568)X(5568) state

The mass and decay constant of the $X(5568)$ state newly observed by D0 Collaboration are computed within the two-point sum rule method using the diquark-antidiquark interpolating current. In calculations, the vacuum condensates up to eight dimensions are taken into account. The obtained result for the mass of the $X(5568)$ state is in a nice agreement with the experimental data.Comment: 5 Pages, 2 Figures and 1 Table; To be published in Phys. Rev. D. arXiv admin note: text overlap with arXiv:1601.0384

Strong Zc+(3900)→J/ψπ+;ηcρ+Z_c^{+}(3900)\rightarrow J/\psi \pi^{+}; \eta_{c} \rho^{+} decays in QCD

The widths of the strong decays $Z_c^{+}(3900)\to J/\psi \pi^{+}$ and $Z_c^{+}(3900)\to \eta_{c} \rho^{+}$ are calculated. To this end, the mass and decay constant of the exotic $Z_c^{+}(3900)$ state are computed by means of a two-point sum rule. The obtained results are then used to calculate the strong couplings $g_{Z_{c}J/\psi \pi }$ and $g_{Z_{c}\eta_{c} \rho }$ employing QCD sum rules on the light-cone supplied by a technique of the soft-meson approximation. We compare our predictions on the mass and decay widths with available experimental data and other theoretical results.Comment: 11 Pages, 3 Figures and 2 Tables; To be published by Physical Review