Aspects of chiral pion-nucleon physics |
| |
| Affiliation: | 1. Université Louis Pasteur, Laboratoire de Physique Théorique, BP 28, F-67037 Strasbourg, France;2. Technische Universität München, Physik Department T39, D-85747 Garching, Germany;3. Forschungszentrum Jülich, IKP (Theorie), D-52425 Jülich, Germany;1. Department of Physics, Kent State University, Kent, OH 44242, United States;2. Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway;3. Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India;4. Faculty of Physics, University of Bielefeld, D-33615 Bielefeld, Germany;1. Theoretical Physics Group, Department of Physics, University of Uyo, Nigeria;2. Department of Basic Sciences, Shahrood Branch, Islamic Azad University, Shahrood, Iran;3. Department of Basic Sciences, Garmsar Branch, Islamic Azad University, Garmsar, Iran;1. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Naka, Ibaraki, Japan;2. Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan;1. The H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków, Poland;2. Institut für Theoretische Physik, Goethe-Universität Frankfurt, D-60438 Frankfurt am Main, Germany;3. Deptartamento d''Estructura i Constituents de la Matèria, Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martì Franquès 1, E-08028 Barcelona, Spain |
| |
| Abstract: | The next-to-leading order chiral pion-nucleon Lagrangian contains seven finite low-energy constants. Two can be fixed from the nucleon anomalous magnetic moments and another one from the quark mass contribution to the neutron-proton mass splitting. We find a set of nine observables, which to one-loop order only depend on the remaining four dimension-two couplings. These are then determined from a best fit. We also show that their values can be understood in terms of resonance exchange related to Δ excitation as well as vector and scalar meson exchange. In particular, we discuss the role of the fictitious scalar-isoscalar meson. We also investigate the chiral expansion of the two P-wave scattering volumes P1− and P2+ as well as the isovector S-wave effective range parameter b−. The one-loop calculation is in good agreement with the data. The difference P1− − P2+ signals chiral loop effects in the πN P-waves. The calculated D- and F-wave threshold parameters compare well with the empirical values. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
