Related papers: Comment on "A phenomenological $\pi^- p$ scatterin…
This article completes a former work where part of the O(p^6) low-energy constants entering in the pi pi scattering were estimated. Some resonance contributions were missed in former calculations and slight differences appeared with respect…
The Compton scattering on a charged pion and the process \gamma\gamma \to \pi^0\pi^0 are studied using the dispersion relations. Unknown parameters of the S-wave \pi\pi interaction, represented as a board Breit-Wignar resonance, and a sum…
Recent attempts to detect the pion polarizability via analysis of $\gamma\gamma\rightarrow\pi\pi$ measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established…
We present a reanalysis of direct CP violation in the decay K_L -> pi^+ pi^- gamma. We point out an existing discrepancy between the theoretical and experimental definitions of epsilon'_{+-gamma}. Adopting the experimental definition of…
The strong K^- p scattering length is extracted within chiral SU(3) unitary approaches from a very large variety of fits to low-energy K^- p scattering data. Very good overall agreement with available scattering data is obtained and the…
This work reviews the available experimental information on the pi-pi scattering lengths, especially the recent near-threshold pi N -> pi pi N data from several laboratories and the related application of the Chew-Low-Goebel (CLG) technique…
We study pion--nucleon scattering with a chiral lagrangian of pions, nucleons, and $\Delta$-isobars. The scattering amplitude is evaluated to one-loop $Q^3$ order, where $Q$ is a generic small momentum, using a new approach which is…
The reaction $\gamma+p\to\gamma'+p+\pi^0$ has been suggested as a means to deduce the $\Delta^+$ magnetic moment. The cross section for this process is estimated in both the constituent quark model and an effective Lagrangian procedure. The…
We review recent progress in our understanding of elastic and inelastic pion reactions on two nucleon systems from the point of view of effective field theory. The discussion includes pion-deuteron scattering, gamma d to pi-nn, and NN to…
A new result for the nucleon sigma term from an updated pion-nucleon partial-wave and dispersion relation analysis of the Virginia Polytechnic Institute (now George Washington University) group is discussed. Using a method similar to that…
Studies on hadron interactions from lattice QCD are reviewed. The $S$-wave $\pi\pi$ scattering lengths of the I=0 and I=2 channels are extracted from various lattice determinations of low energy constants in $N_f=2$ chiral perturbation…
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…
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…
We discuss the possibility to extract the neutron-neutron scattering length a_{nn} from experimental spectra on the reaction gamma d --> pi^+ nn. The transition operator is calculated to high accuracy from chiral perturbation theory. We…
The quasi-free $\gamma d\to\pi^{-}p(p)$ differential cross section has been measured with CLAS at photon beam energies $E_\gamma$ from 0.445 GeV to 2.510 GeV (corresponding to $W$ from 1.311 GeV to 2.366 GeV) for pion center-of-mass angles…
A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the…
Using a chiral unitary approach for meson-baryon scattering in the strangeness zero sector, where the $N^*(1535)$ and $\Delta^*(1700)$ resonances are dynamically generated, we study the reactions $\gamma p \to \pi^0 \eta p$ and $\gamma p…
We reanalyse the gamma-gamma scattering data and conclude that in the mass region below 1 GeV the cross section for gamma-gamma to pi^0-pi^0 can be largely explained by the one pion exchange process with pi-pi rescattering. The radiative…
The $\gamma^* \pi^0 \rightarrow \gamma$ form factor, including the extension off the pion mass-shell, is obtained from a generalized impulse approximation within a QCD-based model field theory known to provide an excellent description of…
The long-distance electromagnetic radiative corrections to tau- -> pi- pi0 nu are re-evaluated. A meson dominance model is used to describe the emission of real photons in this decay. Results obtained for the hadronic spectrum and the decay…