Related papers: Pion polarizabilities: Theory vs Experiment
The anomaly (cusp) in the mass spectrum of two neutral pions from the three-pion decays of charged kaon has been observed in the NA48/2 experiment. Using the recently developed interpretation of this effect in terms of Chiral Perturbative…
We present the pion-pion elastic scattering amplitude at finite temperature to one-loop in Chiral Perturbation Theory. The thermal scattering amplitude properly defined allows to generalize the perturbative unitarity relation to the $T\neq…
A Roy equation analysis of the available $\pi\pi$ phase shift data is performed with the $I=0$ S- wave scattering length $a^0_0$ in the range predicted by the one-loop standard chiral perturbation theory. A suitable dispersive framework is…
I present higher loop order results for several calculations in Chiral perturbation Theory. 1) Two-loop results at finite volume for hadronic vacuum polarization. 2) A three-loop calculation of the pion mass and decay constant in…
Dipole polarizabilities of light pseudoscalar mesons are calculated in the framework of the mean field approach to QCD vacuum and bosonization based on the statistical ensemble of almost everywhere homogeneous Abelian (anti-)self-dual gluon…
We calculate the decay of pionium atoms into two photons. The pion polarizability gives rise to a 10% correction to the corresponding decay width for pointlike pions. This opens the possibility to obtain the difference between the electric…
Understanding a hadron's electric and magnetic polarizabilities allows one to access internal structural information. Traditionally, the external field two-point function method has been used to calculate polarizabilities. However, recent…
Formulas are developed for use in lattice studies of charged hadron polarizabilities. In particular, the valence quark different-flavor component of the charged pion polarizability is examined on a $16^{3}\times 24$ lattice at $\beta=6.0$…
The pion decay constant and mass are computed at low temperature within Chiral Perturbation Theory to two loops. The effects of the breaking of Lorentz Symmetry by the thermal equilibrium state are discussed. The validity of the Gell-Mann…
Elastic pion-pion and pion-nucleon scattering are reviewed in the context of chiral perturbation theory. Theoretical results from systematic low-energy expansions to O(p^6) for pion-pion and to O(p^3) for pion-nucleon scattering are…
We construct effective one-loop vertices and propagators in the linear sigma model at finite temperature, satisfying the chiral Ward identities and thus respecting chiral symmetry, treating the pion momentum, pion mass and temperature as…
CERN COMPASS can investigate pion-photon interactions, to achieve a unique Primakoff Coulomb physics program, centered on pion polarizability and hybrid meson structure studies. COMPASS uses 100-280 GeV beams (muon, pion) and a virtual…
We analyze the Dalitz plot parameters of eta to 3 pion decay in the framework of resummed chiral perturbation theory. This approach allows us to keep the uncertainties in the NNLO and higher orders under better control and estimate their…
We calculate the pion scattering amplitude at nonzero temperature and nonzero $\mu_5$, the chemical potential associated to chiral imbalance in a locally $P$-breaking scenario. The amplitude is calculated up to next to leading order in…
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…
We show that a recent claim of huge kaon loop corrections to the electric dipole amplitude in neutral pion photoprodcution at threshold is incorrect. The difference between the two and three flavor chiral perturbation theory calculation is…
Knowledge of the electric polarizability is crucial to understanding the interactions of hadrons with electromagnetic fields. The neutron polarizability is very sensitive to the quark mass and is expected to diverge in the chiral limit.…
We discuss the thermal behaviour of the pion vector form factors and calculate them in one-loop Chiral Perturbation Theory. The perturbative result is used to analyze the $T$-dependent electromagnetic pion charge radius, obtaining a rough…
Chiral perturbation theory makes definitive predictions for the extrinsic behavior of hadrons in external electric and magnetic fields. Near the chiral limit, the electric and magnetic polarizabilities of pions, kaons, and nucleons are…
Starting from hyperbolic dispersion relations, we derive a system of Roy--Steiner equations for pion Compton scattering that respects analyticity, unitarity, gauge invariance, and crossing symmetry. It thus maintains all symmetries of the…