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We present a calculation of the π-d scattering length in the framework of chiral perturbation theory (ChPT) with focus on virtual-photon effects. Using data on pionic deuterium and pionic hydrogen atoms, we extract the isoscalar and isovector pion–nucleon scattering lengths [Formula: see text] and [Formula: see text], as well as—via the Goldberger–Miyazawa–Oehme sum rule—the charged-pion–nucleon coupling constant [Formula: see text]

With the advent of chiral perturbation theory, the low-energy effective field theory of QCD, high accuracy calculations for hadronic reactions have become possible. We review the recent developments in the reaction NN → NNπ in chiral EFT.

The recent measurements of the reactions [Formula: see text] and [Formula: see text] by the ANKE collaboration at COSY are analyzed with the focus on the p-wave pion production amplitudes. These amplitudes are known to provide an important connection between [Formula: see text] and other low-energy few-nucleon reactions. The results of the recent partial wave analysis of the ANKE data are discussed and compared with the theoretical predictions.

In this review we present the recent advances for calculations of the reactions $NN\to NN\pi$ using chiral effective field theory. Discussed are the next-to-next-to leading order loop contributions with nucleon and Delta-isobar for near threshold s-wave pion production. Results of recent experimental pion-production data for energies close to the threshold are analyzed. Several particular applications are discussed: (i) it is shown how the measured charge symmetry violating pion-production reaction can be used to extract the strong-interaction contribution to the proton-neutron mass difference; (ii) the role of $NN\to NN\pi$ for the extraction of the pion-nucleon scattering lengths from pionic atoms data is illuminated., Comment: 68 pages, 23 figures, to be published in Int. J. Mod. Phys. E