相关论文: Rigorous Effective Field Theory Study on Pion Form…
We investigate the pion scalar form factor in the Meiman-Okubo framework, implementing the phase below the inelastic $K\bar K$ threshold, where it is known from the $\pi\pi$ scalar isoscalar phase shift $\delta_0^0$ by Watson theorem.…
I discuss recent progress in our understanding of the pi pi scattering amplitude at low energy thanks to the combined use of chiral perturbation theory and dispersion relations. I also comment on the criticism raised by Pelaez and Yndurain…
The $J/\psi$ dissociation by $\pi$ and $\rho$ mesons is examined in meson exchange model and compared to the quark interchange model. We found that the main difference between the predictions of the two models could be resolved by the form…
The Standard Model prediction for the magnetic moment of the muon requires a determination of the electromagnetic form factor of the pion at high precision. It is shown that the recent progress in pi-pi scattering allows us to obtain an…
We discuss the impact of chiral symmetry constraints on the quark-mass dependence of meson resonance pole positions, which are encoded in non-perturbative parametrizations of meson scattering amplitudes. Model-independent conditions on such…
We discuss the photon to meson transition form factor for virtual photons, which can be measured in e+ e- collisions. We demonstrate that this form factor is independent of the shape of the meson distribution amplitude over a wide…
Within the Dyson-Schwinger equation approach to modeling QCD for meson physics, we present new results for $g_{\rho\pi\pi}$ and the coupling constants and form factors for the transitions $\gamma^\ast \pi \rho$ and $\gamma^\ast \pi^0…
The elastic and $\gamma \to \pi$ transition form factors of the pion along with its usual static observables are calculated within a light-front field approach to the constituent quark model. The focus of this exercise in a simple model is…
We study a chiral quark model of $\pi$, $\sigma$, $\rho$, and $a_1$ mesons in the large-$N_c$ limit. We show that the quadratic $a_1-\pi$ mixing can be set to zero at zero momentum, thus protecting the $g_{\sigma\pi\pi}$ and…
We construct pi-pi amplitudes that fulfill exact elastic unitarity, account for one loop Chiral Perturbation Theory contributions and include all 1/Nc leading terms, with the only limitation of considering just the lowest-lying nonet of…
We develop a generalized version of heavy-baryon chiral perturbation theory to describe pion-nucleon scattering in a kinematic domain that extends continuously from threshold to the delta-isobar peak. The $P$-wave phase shifts are used to…
The electromagnetic radius of the charged pion and the transition radius of the neutral pion are calculated in the framework of the nonlocal chiral quark model. It is shown in this model that the contributions of vector mesons to the pion…
The strange-quark vector current $\rho$-to-$\pi$ meson transition form factor is computed at one-loop order using strange meson intermediate states. A comparison is made with a $\phi$-meson dominance model estimate. We find that one-loop…
We discuss convergence issues as well as short distance constraints on the deuteron wave functions based on chiral perturbation theory relevant to pion deuteron scattering. Non-analytical terms arise in the multiple scattering series for…
The all--important consequence of Chiral Dynamics for $\pi \pi$ scattering is the Adler zero, which forces $\pi \pi$ amplitudes to grow asymptotically. The continuation of this subthreshold zero into the physical regions requires a…
In this talk I summarize a recently proposed mechanism to understand pi pi scattering to 1 GeV. The model is motivated by the 1/Nc expansion to QCD, and includes a current algebra contact term and resonant pole exchanges. Chiral symmetry…
I briefly review the current status of chiral perturbation theory in the meson sector. Emphasis is given on the quest for higher precision. I discuss two examples: one where it is difficult to make a good prediction (K_L -> pi^0 gamma…
The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and $\Delta$(1232) with dispersion theory. We specifically…
In the scaling regime, amplitudes for backward virtual Compton scattering and hadron annihilation into two photons depend on structure functions that describe the hadron-photon transition at the partonic level. We construct simple…
We explore the impact of perturbative pions on the Unitarity Expansion in the two-nucleon S-waves of Chiral Effective Field Theory at next-to-next-to leading order. Pion exchange explicitly breaks the nontrivial fixed point's universality…