Narrow Results

The decay constants of pseudoscalar and vector heavy–light mesons are calculated in the framework of the relativistic quark model with the completely relativistic treatment of the light quark. It is argued that relativistic effects play a significant role. Good agreement of the model predictions with recent lattice and QCD sum rule calculations as well as available experimental data are found.

We study the masses and decay constants of heavy–light flavor mesons D, D_s, B and B_s in a QCD potential model. The mesonic wave function is used to compute the masses of D and B mesons in the ground state and the wave function is transformed to momentum space to estimate the pseudoscalar decay constants of these mesons. The leptonic decay widths and branching ratio of these mesons for different leptonic channels are also computed to compare with the experimental values. The results are found to be compatible with available data.

In this paper, we use the concept of conformable fractional derivative to study the nonrelativistic radial Schrödinger equation. We suggest an extended version of the Cornell potential as the quark–antiquark interaction of light and heavy mesons. We generalize the asymptotic iteration method to the fractional domain. The latter is used to calculate the energy eigenvalues, as well as the effect of the fractional order $\nu$ on energy spectra. To test the applicability of our model, we use the obtained results to reproduce the mass spectra of some light and heavy mesons such as $b\bar{b}$, $c\bar{c}$, $c\bar{s}$, $\bar{b}c$, $b\bar{q}$ and $b\bar{s}$ quarks. The mass spectra are obtained at different values of the fractional order parameter $\nu$ and were compared with experimental results and other relevant theoretical works. Using the wave function, we calculated the decay constants for heavy-light $D^0$, $D^{+}$, $D_s^{+}$, $B^{-}$, ${\bar{B}}^0$ and ${\bar{B}}_s^0$ mesons. Our results are found to be in good agreement with the experimental data, and improved in comparison with other theoretical previsions.

In this paper, we investigate the mass spectra and decay properties of $B$, $B_s$ and $B_c$ mesons using the relativistic potential model with confining potential $V_q(r)=\frac{1}{2}(1+{\gamma }^0)(a^{2}r+V_0)$. The calculated mass spectra of $B$, $B_s$ and $B_c$ accord to the findings of the experiments and other theoretical forecasts. Using the same parameters, we calculate possible radiative decay widths of $V(ns)\to P(ns)\gamma$ and $P(ns)\to V(ns)\gamma$, $n=1,2,3$ and weak leptonic decay constants of $B$, $B_s$ and $B_c$ mesons. Our results, in most cases, generally agree with experimental and other theoretical predictions. Finally, we also investigate mixing parameters $x_q$, $y_q$ and ${\chi }_q$ for $B_q^0-{\overline{B}}_q^0$$(qϵd,s)$ mesons, where our calculated values reasonably agree with the experiment.

In this paper, we study the mass spectrum and decay constants of ground state (1S) and radially excited states (2S and 3S) of heavy equal mass pseudoscalar mesons, η_c and η_b. We have employed the framework of Bethe–Salpeter equation (BSE) under Covariant Instantaneous Ansatz (CIA). Our predictions are in reasonable agreement with the data on available states and results of other models.

In this paper, we calculate the mass spectrum, weak decay constants, two photon decay widths, and two-gluon decay widths of ground ($1S$) and radially excited ($2S,3S,\dots$) states of pseudoscalar charmoniuum and bottomonium such as ${\eta }_c$ and ${\eta }_b$, as well as the mass spectrum and leptonic decay constants of ground state ($1S$), excited ($2S,1D,3S,2D,4S,\dots ,5D$) states of vector charmonium and bottomonium such as $J/\psi$, and $\mathrm{{\rm Y}}$, using the formulation of Bethe–Salpeter equation under covariant instantaneous ansatz (CIA). Our results are in good agreement with data (where ever available) and other models. In this framework, from the beginning, we employ a $4\times 4$ representation for two-body ($q\overline{q}$) BS amplitude for calculating both the mass spectra as well as the transition amplitudes. However, the price we have to pay is to solve a coupled set of equations for both pseudoscalar and vector quarkonia, which we have explicitly shown get decoupled in the heavy-quark approximation, leading to mass spectral equation with analytical solutions for both masses, as well as eigenfunctions for all the above states, in an approximate harmonic oscillator basis. The analytical forms of eigenfunctions for ground and excited states so obtained are used to evaluate the decay constants and decay widths for different processes.

The mass spectra and decay properties of $B$ and $B_s$ mesons are obtained using the nonrelativistic potential model by applying the variational approach. The quark–anti-quark potential used in our model consists of a Hulthen potential and a confining linear potential. The hyper-fine interaction is introduced to obtain the splittings of the spin-singlet and triplet states, while the spin–orbit and tensor interactions provide the fine structure splittings. The model parameters and the wave functions that reproduce the mass spectra are used to investigate the decay properties of $B$ and $B_s$ mesons. The mass spectra of $B$ and $B_s$ mesons have been enhanced using coupled channel effects.

We first review recent measurements of D → μν and D_s → μν, τν from CLEO-c. These decays are used to determine leptonic decay constants f_D and f_Ds which may be compared to modern Lattice QCD (LQCD) calculations. Such cross-checks can provide confidence in Lattice results for B_(s) meson decay constants which are needed to fully exploit data used to extract the CKM matrix elements V_ub and V_cb. We also comment briefly on the outlook for further progress at BESIII.

We briefly review motivation and results of the approach to QCD vacuum as a medium describable in terms of statistical ensemble of almost everywhere constant Abelian (anti-)self-dual gluon fields. An overview of the hadronization formalism based on this ensemble is presented. New results for radial excitations of light, heavy-light mesons and heavy quarkonia are presented. A possible interrelation between the present approach and holographic QCD with harmonic confinement is outlined.

In BES experiments, studies of charmed meson decays were initially started with the BESI data taken at $\sqrt{s}=4.04\text{GeV}$ in the middle 1990s, and then extended with the BESII data taken around $\sqrt{s}=3.773\text{GeV}$ in 2000s. In 2010s, many important results from studies of charmed meson decays were reported, with the world largest threshold data samples at BESIII. Here gives a brief review on charmed meson physics at BESIII.