Author
N. Kaiser
Other affiliations: Niels Bohr Institute
Bio: N. Kaiser is an academic researcher from Technische Universität München. The author has contributed to research in topics: Nucleon & Pion. The author has an hindex of 19, co-authored 41 publications receiving 2095 citations. Previous affiliations of N. Kaiser include Niels Bohr Institute.
Papers
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TL;DR: In this paper, the implications of spontaneous chiral symmetry breaking in QCD for processes involving one, two, or more nucleons are discussed, and the results of the analysis are discussed.
Abstract: We review the implications of the spontaneous chiral symmetry breaking in QCD for processes involving one, two, or more nucleons.
906 citations
TL;DR: In this paper, a set of nine observables, which to one-loop order only depend on the remaining four dimension-two couplings, were determined from a best fit.
188 citations
TL;DR: In this article, a set of nine observables, which to one loop order do only depend on the remaining four dimension two couplings, are determined from a best fit, and their values can be understood in terms of resonance exchange related to vector and scalar meson exchange.
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 do 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 $\Delta$ 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 $P_1^-$ and $P_2^+$ as well as the isovector S-wave effective range parameter $b^-$. The one-loop calculation is in good agreement with the data. The difference $P_1^- - P_2^+$ signals chiral loop effects in the $\pi N$ P-waves. The calculated D- and F-wave threshold parameters compare well with the empirical values.
155 citations
TL;DR: In this article, the chiral corrections to Weinberg's prediction for the S-wave πN scattering lengths up to and including order O (M π 3 ) making use of heavy baryon chiral perturbation theory.
85 citations
TL;DR: In this article, the authors investigated threshold pion photoproduction in the framework of heavy baryon chiral perturbation theory and gave the expansion of the electric dipole amplitude E 0+ to three orders in μ the ratio of the pion to nucleon mass, and showed that it is slowly converging.
Abstract: We investigate threshold pion photoproduction in the framework of heavy baryon chiral perturbation theory. We give the expansion of the electric dipole amplitude E
0+ to three orders in μ the ratio of the pion to nucleon mass, and show that it is slowly converging. We argue that this observable is not a good testing ground for the chiral dynamics of QCD. In contrast, we exhibit new and fastly converging low-energy theorems in the P-waves which should be used to constrain the data analysis. We also discuss the importance of polarization observables to accurately pin down certain multipoles and give predictions for the reaction γ
n → π0
n.
81 citations
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TL;DR: In this article, the nuclear forces can be derived using effective chiral Lagrangians consistent with the symmetries of QCD, and the status of the calculations for two and three nucleon forces and their applications in few-nucleon systems are reviewed.
Abstract: Nuclear forces can be systematically derived using effective chiral Lagrangians consistent with the symmetries of QCD. I review the status of the calculations for two- and three-nucleon forces and their applications in few-nucleon systems. I also address issues like the quark mass dependence of the nuclear forces and resonance saturation for four-nucleon operators.
1,455 citations
TL;DR: Recently, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model as discussed by the authors, and investigated various theoretical interpretations of these candidates of the multiquark states.
1,083 citations
TL;DR: In this paper, the implications of spontaneous chiral symmetry breaking in QCD for processes involving one, two, or more nucleons are discussed, and the results of the analysis are discussed.
Abstract: We review the implications of the spontaneous chiral symmetry breaking in QCD for processes involving one, two, or more nucleons.
906 citations
Abstract: We review how nuclear forces emerge from low-energy QCD via chiral effective field theory. The presentation is accessible to the non-specialist. At the same time, we also provide considerable detailed information (mostly in appendices) for the benefit of researchers who wish to start working in this field.
883 citations
TL;DR: In this article, the nuclear forces emerge from low-energy QCD via chiral eective theory, and the authors provide considerable detailed information for the benet of researchers who wish to start working in this field.
878 citations