Eur. Phys. J. A (2013) 49: 20
https://doi.org/10.1140/epja/i2013-13020-1

Regular Article - Theoretical Physics

Threshold neutral pion photoproduction off the tri-nucleon to O(q⁴)

¹ Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, D-53115, Bonn, Germany
² Ruhr-Universität Bochum, Institut für Theoretische Physik II, D-44870, Bochum, Germany
³ Forschungszentrum Jülich, Institut für Kernphysik (IKP-3), Institute for Advanced Simulation (IAS-4) and Jülich Center for Hadron Physics, D-52425, Jülich, Germany

Received: 24 September 2012
Revised: 14 December 2012
Accepted: 9 January 2013
Published online: 11 February 2013

Abstract

We calculate the electromagnetic neutral pion production off tri-nucleon bound states (³H, ³He) at threshold in chiral nuclear effective field theory to fourth order in the standard heavy baryon counting. We show that the fourth-order two-nucleon corrections to the S-wave multipoles at threshold are very small. This implies that a precise measurement of the S-wave cross section for neutral pion production off ³He allows for a stringent test of the chiral perturbation theory prediction for the S-wave electric multipole .