Related papers: The coupling constant g$_{\rho\sigma\gamma}$ as de…
We derive a QCD sum rule for the flavour-singlet axial coupling constant $g_A^{(0)}$ from a two point correlation function of flavour-singlet axial vector currents in a one-nucleon state. In evaluating the correlation function by an…
Based on the one-boson-exchange framework that the $\sigma$ meson serves as an effective parameterization for the correlated scalar-isoscalar $\pi\pi$ interaction, we calculate the coupling constants of the $\sigma$ to the $\frac{1}{2}^+$…
If quantum chromodynamics (QCD) is renormalized by minimal subtraction (MS), at higher orders, the strong coupling constant alpha_s and the quark masses m_q exhibit discontinuities at the flavour thresholds, which are controlled by…
The coupling constant of (phi -> K K) decay is calculated in light cone QCD sum rules. The result obtained for g_{phi KK} = (4.9 pm 0.8) is in a good agreement with the existing experimental result.
Recently BES at BEPC found evidence for the existence of the $\sigma$ meson in the process of $J/\Psi \to \sigma\omega \to\pi\pi\omega$. In this paper we firstly discuss the relevant coupling $g_{\sigma\pi\pi}$ and show that the linear…
This paper presents a summary of the current status of determinations of the strong coupling constant alpha_s. A detailed description of the definition, scale dependence and inherent theoretical ambiguities is given. The various physical…
The value of the $\Lambda(1405){\bar K}N$ coupling constant $g_{\Lambda(1405)\bar{K}N}$ is obtained by fitting it to the experimental data on the total cross sections of the $K^-p \to \pi^0\Sigma^0$ reaction. On the basis of an effective…
We analytically compute the five-loop term in the beta function which governs the running of $\alpha_s$ --- the quark-gluon coupling constant in QCD. The new term leads to a reduction of the theory uncertainty in $\alpha_s$ taken at the…
The theoretical evaluation of the coupling constants gpiNN , gKNLambda and gKNSigma is undertaken using QCD sum rules. These quantities were previously calculated with exponential (Borel) kernels used to suppress the unknown contributions…
The DDrho form factor is evaluated in a QCD sum rule calculation for both D and rho off-shell mesons. We study the double Borel sum rule for the three point function of two pseudoscalar and one vector meson currents. We find that the…
We compute the matching relation for the strong coupling constant within the framework of QCD up to four-loop order. This allows a consistent five-loop running (once the $\beta$ function is available to this order) taking into account…
Coupling constants of $\rho$- and $\omega$- meson-nucleon are related with each other by isospin relation. In present work, it is aimed at studying the violation (if it exists) of isospin symmetry of the $\omega$-meson and to study the…
The transition constant for the hadronic decay $\omega \rightarrow \rho\pi$ is investigated by means of QCD sum rules in external axial field. The obtained value for $g_{\omega\rho\pi}$ is about 16 GeV${}^{-1}$ that is in a good agreement…
We calculate the $\rho$ meson couplings between the heavy hybrid doublets H^h/S^h/M^h/T^h and the ordinary q\bar{Q} doublets in the framework of the light-cone QCD sum rule. The sum rules obtained rely mildly on the Borel parameters in…
We employ QCD sum rules to calculate the $J/\psi DD^*$ form factors and coupling constant by studying the three-point $J/\psi D^*D$ correlation function. We find that the momentum dependence of the form factor depends on the off-shell…
We calculate the coupling constants between the light vector mesons and heavy baryons within the framework of the light-cone QCD sum rule in the leading order of heavy quark effective theory. Most resulting sum rules are stable with the…
The axial-vector coupling $g_A$ of a constituent quark is estimated from matching the constituent quark model to the operator product expansion in QCD in the limit of large number of colours under some assumptions. The obtained relation is…
The frequency dependent conductivity $\sigma(\omega)$ of the strongly coupled Quark-Gluon Plasma (QGP) is estimated using a bottom up holographic model that can adequately describe recent lattice data for QCD thermodynamics at zero chemical…
The strong coupling constant $g_{\Upsilon B_c^{ps} B_c^V}$ is evaluated using the three-point QCD sum rules. The correlation functions used to calculate these strong coupling constants contain contributions of both $B_c^V$ and $B_c^{ps}$…
Over 40 years after the calculation of the 1-loop QED corrections to the muon lifetime, new theoretical developments have made it possible to obtain an analytic expression for the complete 2-loop QED contributions in the Fermi theory. The…