Narrow Results

A recently proposed strictly phenomenological static quark–antiquark potential belonging to the generality V(r) = -Ar^-α + κr^β + V₀ is tested with heavy quarkonia in the context of the shifted large N-expansion method. This nonrelativistic potential model fits the spin-averaged mass spectra of the , and quarkonia within a few MeV and also the five experimentally known leptonic decay widths of the and vector states. Further, we compute the hyperfine splittings of the bottomonium spectrum as well as the fine and hyperfine splittings of the charmonium spectrum. We give predictions for not yet observed B_c splittings. The model is then used to predict the masses of the remaining quarkonia and the leptonic decay widths of the two pseudoscalar states. Our results are compared with other models to gauge the reliability of the predictions and point out differences.

We investigate the weak leptonic and semileptonic decay widths of pseudoscalar light and heavy mesons in a Dirac formalism. We take relativistic-independent quark model of the form $V_q(r)=\frac{1}{2}(1+{\gamma }^0)(a^{2}r+V_0)$, where $a>0$. This is computed using the binding quark eigenfunction and taking the assumptions of a significant relationship between the quark and antiquark momenta inside the decaying meson in the rest frame. To calculate the decay constant $(f_M)$, decay width and branching fractions of pseudoscalar mesons, we employ the model parameters that we used earlier. The experimental findings and various similar models are in good agreement with our predictions such as $“f_{B_C}>f_{B_S}>f_B,f_{D_S}>f_D,f_D>f_B$ and $f_B>f_{\pi }$”. Finally, we calculate the form factors and branching fractions for the semileptonic $D(D^0)$ decays $“D^{+}\to K_S^0{e}^{+}{\nu }_e$, $D^{+}\to K_L^0{e}^{+}{\nu }_e$, $D^{+}\to {\pi }^0{e}^{+}{\nu }_e$, $D^0\to K^{-}{e}^{+}{\nu }_e$ and $D^0\to {\pi }^{-}{e}^{+}{\nu }_e$” and find reasonable agreement with the experimental results.

In this work, we have employed Bethe–Salpeter equation (BSE) under Covariant Instantaneous Ansatz (CIA) to study radiative decays of light vector mesons through the process: h→h'γ, taking h and h' as equal mass light vector and pseudoscalar mesons, respectively. The decay widths calculated for these processes are in reasonable agreement with data. The motivation for this work was our intention to resolve the problems involved in calculations of triangle quark-loop diagrams which appear in processes such as radiative meson decays, meson form factors, strong decays of mesons, etc., in BSE under CIA, which give rise to complexities in amplitudes (as pointed out earlier in Ref. 1) due to the presence of the time-like momentum components in Gaussian factors associated with the vertex functions of the participating hadrons. In this work we try to highlight this problem and then demonstrate a mathematical procedure which might lead to calculations of such processes in BSE under CIA.

In this work, we have employed Bethe–Salpeter equation (BSE) under Covariant Instantaneous Ansatz (CIA) to study strong decays of first radial excitations, ω(1420) and ρ(1450) of lightest vector mesons, ω(782) and ρ(770) respectively, through the processes: ω(1420)→ρ+π and ρ(1450)→ω+π. The main motivation for this work was our intention to resolve the problems involved in calculations of triangle quark-loop diagrams as pointed out earlier in Ref. 1 which appear in processes such as h→h'+h" and h→h'+γ (attempted recently) in BSE under CIA, which gives rise to complexities in amplitudes making calculations difficult. We explicitly show the mathematical procedure for handling the process, h→h'+h" involving three hadron–quark vertex functions, which is more involved than that for h→h'+γ and leads to decay widths which are in rough agreement with data.