Neutral pion photoproduction off 3H and 3He in chiral perturbation   theory
  We calculate electromagnetic neutral pion production off three-nucleon bound states (3H, 3He) at threshold to leading one-loop order in the framework of chiral nuclear effective field theory. In addition, we analyze the dependence of the nuclear S-wave amplitude E_{0+} on the elementary neutron amplitude E_{0+}^{pi0 n} which in the case of 3He provides a stringent test of the prediction based on chiral perturbation theory. Uncertainties from higher order corrections are estimated. 
Mark Lenkewitz, Evgeny Epelbaum, H.-W. Hammer, Ulf-G. Mei{\ss}ner
nucl-th hep-ph