相关论文: QCD S Parameter from Inhomogeneous Bethe-Salpeter …

The Bethe--Salpeter equation for the pion in chiral symmetric models is studied with a special care to consistency with low-energy relations. We propose a reduction of the rainbow Schwinger--Dyson and the ladder Bethe--Salpeter equations…

We use QCD sum rules to obtain the weak parity-violating pion-nucleon coupling constant $f_{\pi NN}$. We find that $f_{\pi NN}\approx 2\times 10^{-8}$, about an order of magnitude smaller than the ``best estimates'' based on quark models.…

Using the correlation function of the axial vector mesons, we present a QCD sum rule calculation for the decay constants f_pi and f_K. Our calculations are only weakly dependent on the SU(3) breaking-parameter for the QCD vacuum and give…

In this report, computational techniques are employed to extract the energy eigenvalues of the pion from two-point correlation function data that has been simulated using the lattice formulation of Quantum Chromodynamics (QCD) across…

Poincar\'e-covariant Bethe-Salpeter wave functions are used to calculate light-front wave functions (LFWFs) of the pion, $\pi$, and an analogue state, $\pi_{s\bar s}$. The current masses of the degenerate valence constituents in the…

We perform a detailed, fully-correlated study of the chiral behavior of the pion mass and decay constant, based on 2+1 flavor lattice QCD simulations. These calculations are implemented using tree-level, O(a)-improved Wilson fermions, at…

We study leptonic and semi-leptonic decays of D and B mesons. Use of the Hopping Parameter Expansion (HPE) for two-point functions allows us continuously to vary the pseudoscalar mass from below m_D up towards m_B. We compute the…

We have computed the form factors for B --> pi and D --> K(pi) semileptonic decays on the lattice by using full non-perturbative O(a) improvement, in the quenched approximation. Our results are expressed in terms of few parameters which…

We study the lowest lying $\pi^+ \pi^-$ resonance R, bound by the long range Coulomb potential and destabilized by short range strong interactions mediating the dominant decay into two neutral pions. Parametrizing the corresponding partial…

The Global Color-symmetry Model of QCD is extended to deal with a background electromagnetic field and the associated conserved current is identified for composite $\bar{q}q$ pion modes of the model. Although the analysis is limited to tree…

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 electromagnetic pion form factor, $F_\pi(q^2)$, is calculated for spacelike-$q^2$ in impulse approximation using a confining quark propagator, $S$, and a dressed quark-photon vertex, $\Gamma_\mu$, obtained from realistic,…

We calculate the light pseudoscalar decay constants, f_pi and f_K, and their ratio using domain wall valence quarks and 2+1 flavors of dynamical staggered quarks. Use of the MILC gauge configurations allows us to simulate at several sea…

We present our result for the $K\to\pi\pi$ decay amplitudes for both the $\Delta I=1/2$ and $3/2$ processes with the improved Wilson fermion action. In order to realize the physical kinematics, where the pions in the final state have finite…

The rainbow truncation of the quark Dyson-Schwinger equation is combined with the ladder Bethe-Salpeter equation for the dressed quark-photon vertex to study the low-momentum behavior of the pion electromagnetic form factor. With model…

In this work, we calculate the $CP$-averaged branching ratios and direct $CP$-violating asymmetries of the quasi-two-body decays $B_{(s)}\to P f_2(1270)\to P\pi\pi$ with the two-pion distribution amplitude $\Phi_{\pi\pi}^{\rm D}$ by using…

We present results for the leptonic decay constants of the D and D$_{\rm s}$ mesons from $N_{\rm f}=2+1$ lattice QCD. We employ a set of 49 high statistics gauge ensembles generated by the Coordinated Lattice Simulations (CLS) effort…

We estimate the QCD effective charge $\alpha_s$ in the low-energy region by exploiting the conventional meson spectrum within a relativistic quantum-field model based on analytic confinement. The ladder Bethe-Salpeter equation is solved for…

We present an investigation of various gauge invariant definitions of the $q\bar q$ Bethe-Salpeter (BS) amplitude for mesons in lattice QCD, and compare them to the Coulomb and Landau gauge BS amplitudes. We show that the gauge invariant BS…

In the framework of the instantaneous Bethe Salpeter equation we investigate weak decays of B and D mesons. Mesons are described as q-bar q states interacting via a mixture of a scalar and a vector confining kernel and a one gluon exchange.…