Abstract
While attempts to solve the equations of Quantum Chromodynamics (QCD) numerically in the low energy limit are increasingly successful ("lattice QCD"), Chiral Effective Field Theory (ChEFT) remains a potent alternative method for deriving nuclear force potentials. Previous calculations within framework of ChEFT up to 4th order (next-to-next-to-next-to-leading order, N3LO) show generally good agreement with experiment. However, some persistent problems with N3LO potentials as well as the question of order-by-order convergence of ChEFT require calculations up to higher orders. In this work, I present calculations of pion exchange contributions to nucleon-nucleon potentials up to 5th and 6th order (N4LO and N5LO). N4LO calculations solve some of the previous persistent problems and improve the agreement with nucleon-nucleon (NN) scattering experiments in peripheral partial waves. N5LO contributions further improve the agreement with experiment and also turn out to be smaller compared to N4LO, thus showing the trend for convergence. Finally, I present the full NN potential at N4LO, which shows excellent agreement with experimental data in all partial waves and can be applied further in nuclear structure calculations. Since a modified power counting scheme is used for N4LO potential, full NN potentials at NLO, NNLO and N3LO are also recalculated using the modified scheme. This allows for systematic truncation error estimation when applying potentials to calculations of nuclear structure and reactions.