Chiral Dynamics in Few-nucleon Systems

Download or read book Chiral Dynamics in Few-nucleon Systems written by Evgeny Epelbaum and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chiral Effective Field Theory (EFT) has become a standard tool for analyzing the properties of hadronic systems at low energy in a systematic and controlled way based upon the approximate and spontaneously broken chiral symmetry of Quantum Chromodynamics (QCD). Based on Weinberg's idea to use chiral EFT to derive nuclear forces, this method has also been successfully applied to a few-nucleon problems. Energy-independent and hermitian nuclear potentials can be derived from the chiral Lagrangian e.g. using the method of unitary transformation. This scheme can also be applied to derive the corresponding nuclear current operator. They have used this framework to study the 2N system at next-to-next-to-next-to-leading order (N3LO) in the chiral expansion. The theoretical uncertainty for scattering observables at N3LO is expected to be of the order (almost equal to) 0.5%, 7% and 25% at laboratory energy (almost equal to) 50, 150 and 250 MeV. The findings agree well with these estimations. Three- and more-nucleon systems have been considered so far up to next-to-next-to-leading order. For the first time, the complete chiral three-nucleon force has been included in few-body calculations, which starts to contribute at this order. N3LO analysis of> 2N systems is in progress. Recently they have worked out the leading and subleading isospin-violating 3N forces using the method of unitary transformation, which are largely driven by nucleon and pion mass differences. The work on isospin-breaking 2N forces is underway.