Dynamical chiral symmetry breaking and confinement are two emergent phenomena of QCD, orchestrating the observed spectrum of hadrons and their static as well dynamic properties, providing as much as 98% mass of the luminous matter which permeates our universe. Their study in the continuum can be naturally carried out through QCD’s fundamental field equations, namely, Dyson-Schwinger equations to predict a host of hadronic observables.
We study the internal structure of neutral pseudoscalar mesons via two photon transition form factors. The evolution of these form factors as a function of the probing momentum of the photons is governed by the parton distribution amplitude. Our analysis is based upon a symmetry preserving treatment of Dyson-Schwinger and Bethe-Salpeter equations. Within a single systematic and consistent approach, with a traceable connection to QCD, the description of these form factors, pion elastic form factor, parton distribution amplitudes and many other hadron properties is obtained satisfactorily and predictions are made for future experiments. Precise understanding of the neutrino-nucleus reactions