相关论文: Pion mass and decay constant

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…

Two pion effective mass and helicity angle distributions in the charged B-meson decays into three charged pions are studied. The weak decay amplitudes are calculated in the framework of the QCD factorization approximation. The strong…

We study the topological susceptibility, chi, in QCD with two quark flavours using lattice field configurations that have been produced with an O(a) improved quark action. We find clear evidence for the expected suppression at small quark…

We argue that the recent BaBar data on $\gamma \to \pi$ e.m. transition form factor at large photon virtuality supports the idea that pion distribution amplitude (DA) is close to unity with $\phi_\pi^\prime(0)/6\gg 1$ at a normalization…

Recently, a theoretical framework was set up in [1], which allows for the symmetry-preserving inclusion of full quark-gluon vertices in the description of the meson dynamics. In the present work, we develop a special truncation within this…

We review the recent measurements of the rare pion decays: Pi+ -> Pi0 e+ Nu [pion beta, Pi_(e3), or Pi_beta decay], radiative decay Pi+ -> e+ Nu Gamma [Pi_(e2Gamma) or RPD], and Pi+ -> e+ Nu [Pi_(e2)] decay, as well as the radiative muon…

We have studied radiative pion decays Pi+ -> e+ nu gamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 42,209 events we have evaluated absolute Pi -> e nu gamma…

The QCD sum rule calculation of the in-medium pion decay constants using pseudoscalar-axial vector correlation function, $i \int d^4x e^{ip\cdot x} < \rho| T[{\bar d}(x) i \gamma_5 u (x) {\bar u}(0) \gamma_\mu \gamma_5 d (0)] | \rho>$ is…

We perform a lattice QCD calculation of the \pi^0\to\gamma\gamma transition form factor and the associated decay width. We use a Euclidean time integral of the relevant three-point function to compute the decay amplitude for two-photon…

In the epsilon-regime of lattice QCD one can get an accurate measurement of the pion decay constant F_pi by monitoring how just one single Dirac operator eigenvalue splits into two when subjected to two different external vector sources.…

The study of radiative phi decays into scalar mesons, with subsequent decay into pi pi gamma, constitutes an important topic at the electron-positron collider DAPHNE. The interference of the respective amplitude with the one for pi+ pi-…

Complex poles of the unitarized pi-pi scattering amplitude in nuclear matter are studied. Partial restoration of chiral symmetry is modeled by the decrease of in-medium pion decay constant f*_{pi}. For large chiral restoration…

The Lattice results for the pion and kaon decay constants are analysed within the Resonance Chiral Theory framework in the large NC limit. The approximately linear behaviour of the observable at large light-quark mass is explained through…

The dependence of the nucleon mass on the mass of the pion is studied in the framework of the chiral quark-soliton model. A remarkable agreement is observed with lattice data from recent full dynamical simulations. The possibility and…

The electric ${\alpha}_{\pi}$ and magnetic $\beta_{\pi}$ charged pion Compton polarizabilities are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD).They are directly linked to the phenomenon of spontaneously…

We extend an effective Lagrangian embodying broken scale and chiral symmetry to include explicit chiral symmetry breaking and an additional chiral invariant term which allows for an axial coupling constant greater than unity. We also…

The dimensionless parameter $\xi' = M^2/(16 \pi^2 F^2)$, where $F$ is the pion decay constant in the chiral limit and $M$ is the pion mass at leading order in the quark mass, is expected to control the convergence of chiral perturbation…

Consider the effective lagrangian for pions in the chiral limit, computed to leading order in an expansion about zero temperature. To describe the scattering of pions with small momenta, it is necessary to include not just the usual shift…

We study light-quark observables by means of dynamical lattice QCD simulations using two flavours of twisted mass fermions at maximal twist. We employ chiral perturbation theory to describe our data for the pion mass and decay constant. In…

We analyse the radiative decay $\eta \to \pi^+\pi^- \pi^0\gamma$ in the low--energy expansion of the Standard Model. We employ the notion of ``generalized bremsstrahlung'' to take full advantage of the theoretical and experimental…