Related papers: Compton scattering by pion: there is no room for t…
We calculate the pion-pion elastic scattering phase shifts for pion masses from the chiral limit to values of interest for lattice studies. At low energies, we use the standard Chiral Perturbation Theory expressions to one and two loops. In…
We study the contributions from the connected and disconnected contraction diagrams to the pion-kaon scattering amplitude within the framework of SU$(4|1)$ partially-quenched chiral perturbation theory. Combining this with a finite-volume…
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…
We discuss the virtual Compton scattering amplitude $\gamma^\ast+\pi\to \gamma+\pi$ which enters the reaction $\pi^-+e^-\to\pi^-+e^-+\gamma$. The low-energy scattering amplitude is divided into a model-independent part, involving only the…
We study the properties of the Resonance-Spectrum Expansion near threshold in I=0 S-wave pion-pion scattering. The real part of the amplitude, when extrapolated from above threshold to below threshold, is found to vanish at a positive…
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 discuss a recent computation of Compton scattering on the deuteron at photon energies of order the pion mass. An interaction kernel is computed in baryon chiral perturbation theory and sewn to phenomenological deuteron wave functions. As…
Off-shell effects in proton electromagnetic vertices can be constrained from their effects on known processes. In particular, parameters in models for the off-shell effects can be determined by fitting to the proton electric and magnetic…
We compute the scattering amplitude in Wilson Chiral Perturbation Theory for two flavors. The lattice spacing effects due to the explicit chiral symmetry breaking are kept through O(a^2), and we consider the regime where the quark mass m is…
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 $T\neq…
We use chiral perturbation theory to study the extraction of pion electromagnetic polarizabilities from lattice QCD. Chiral extrapolation formulae are derived for partially quenched QCD, and quenched QCD simulations. On a torus, volume…
We present a parameter--free calculation of the dispersive and absorptive contributions to the pion--deuteron scattering length based on chiral perturbation theory. We show that once all diagrams contributing to leading order to this…
We recalculated pion virtual Compton scattering in perturbative QCD in this paper. Our calculation avoids some deficiencies in existing literatures, and treats real Compton scattering as a limit case in which the mass of the virtual photon…
First it is shown that the tree amplitude for pion pion scattering in the minimal linear sigma model has an exact expression which is proportional to a geometric series in the quantity (s-$m_\pi^2$)/($m_B^2-m_\pi^2$), where $m_B$ is the…
The electric ($\alpha_\pi$) and magnetic ($\beta_\pi$) Compton polarizabilities of both the charged and the neutral pion are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). Pion polarizabilities affect the…
A new power-counting scheme for a chiral effective field theory that includes Delta degrees of freedom is briefly described and applied to the nucleon Compton scattering.
We analyze in detail the problem of gauge invariance of the deeply vitual Compton scattering (DVCS) amplitude. Using twist 3 one-gluon exchange diagram contributions and the QCD equations of motion, we derive the general gauge invariant…
The leading non-Coulombic electromagnetic contributions to pi pi s-wave scattering lengths are computed in Chiral Perturbation Theory. It is shown that these corrections are zeroth order in the chiral expansion and associated with…
We summarize results from our recent paper* on nucleon Compton scattering in the Dyson-Schwinger approach. We study the Compton scattering phase space and its various kinematic limits, and we introduce a covariant, transverse tensor basis…
The large N effective action of the non-linear sigma model based in the coset O(N+1)/O(N) is obtained. The renormalization of this effective action requires the introduction of an infinite set of counterterms. However, there exit particular…