Related papers: f_K/f_pi ratio from QCD sum rules
Decay constant of eta-meson f is calculated on the basis of the QCD sum rule method. An instanton contribution is taken into account. The result is f = 0.17 GeV.
Masses and decay constants of the scalar quarkonia, $\chi_{Q0} (Q=b,c)$ with quantum numbers $I^G(J^{PC})=0^{+}(0^{++})$ are calculated in the framework of the QCD sum rules approach both in vacuum and finite temperature. The masses and…
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant $f_{B_c}$, and revisit $f_B$ and $f_{B_s}$. Results exhibit excellent stability in a wide range of values of the…
We compute the decay constants of the lowest ccbar-states with quantum numbers J(PC)=0(-+) [eta_c], 1(--) [J/psi], and 1(+-) [hc] by using lattice QCD and QCD sum rules. We consider the coupling of J/psi to both the vector and tensor…
We calculate the mass and decay constant of $I=1/2$ scalar mesons composed of quark-antiquark pairs based on QCD sum rule. The quauk-antiquark pairs can be $s\bar{q}$ or $q\bar{s}$ ($q=u,d$) in quark model, the quantum numbers of spin and…
We provide a set of sum rules relating CP-averaged branching ratios and CP-asymmetries of the $B \to \pi K$ modes. They prove to be useful as a mechanism to `test' experimental data given our expectations of the size of isospin breaking. A…
In the present work, the temperature dependence of the scalar mesons parameters is investigated in the framework of thermal QCD sum rules. We calculate sigma-pole and the non-resonant two-pion continuum contributions to the spectral…
We present a non-perturbative calculation for the pion decay constant with quenched Kogut-Susskind quarks. Numerical simulations are carried out at $\beta = 6.0$ and 6.2 with various operators extending over all flavors. The renormalization…
We study the Schwinger model with $N_{\rm f} \geq 2$ degenerate fermion flavors, by means of lattice simulations. We use dynamical Wilson fermions for $N_{\rm f} = 2$, and re-weighted quenched configurations for overlap-hypercube fermions…
Pion beta decay, $\pi^+\to \pi^0 e^+\nu(\gamma)$, provides a theoretically clean $\pm 0.3\%$ determination of the CKM matrix element $V_{\text{ud}}$. That value falls short of super-allowed nuclear beta decays where an order of magnitude…
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…
We calculate the low-energy parameter S in QCD, which is also known as L_{10}, and the pion decay constant f_\pi using inhomogeneous Bethe-Salpeter equation in improved ladder approximation. To extract these quantities we calculate the…
The mass and decay constant of the ground state strange tensor meson $K_2^*(1430)$ with $I(J^P)=1/2(2^+)$ is calculated using the QCD sum rules method. The results are consistent with the experimental data. It is found that SU(3) symmetry…
We present results from an analysis of the light spectrum and the decay constants f_{\pi} and f_V^{-1} in Full QCD with n_f=2 Wilson fermions at a coupling of beta=5.6 on a 16^3x32 lattice.
We compute decay constants of heavy-light mesons in quenched lattice QCD with a lattice spacing of a ~ 0.04 fm using non-perturbatively O(a) improved Wilson fermions and O(a) improved currents. We obtain f_{D_s} = 220(6)(5)(11) MeV, f_D =…
We estimate the decay constants $f_\pi$ and $f_K$ of the light mesons within a relativistic quantum-field model of interacting quarks and gluons confined analytically. The necessary physical parameters, the quark masses $m_u$ and $m_s$, the…
The correlation function of two pseudoscalar charmed quark currents with a positive hadronic spectral density is employed to obtain upper bounds on the decay constants of $D$ and $D_s$ mesons. Including all known terms of the…
Extending previous work we study the constraints of QCD sum rules on mass and width of light vector and axial-vector mesons in vacuum and in a medium with finite nuclear density. For the latter case especially the effect of nuclear pions…
In this article, we take the point of view that the light scalar meson $a_0(980)$ is a conventional $q\bar{q}$ state, and calculate the coupling constants $g_{a_0\eta\pi^0}$ and $g_{a_0 \eta'\pi^0}$ with the light-cone QCD sum rules. The…
We provide a set of sum rules, using flavour symmetries, relating CP-averaged ratios and CP asymmetries of different neutral and charged B mesons decaying into an eta(') particle together with a pion, a kaon or a second eta('). These sume…