Two-photon physics

Abstract

It is reviewed how Compton scattering sum rules relate low-energy nucleon structure quantities to the nucleon excitation spectrum. In particular, the GDH sum rule and recently proposed extensions of it will be discussed. These extensions are sometimes more calculationally robust, which may be an advantage when estimating the chiral extrapolations of lattice QCD results, such as for anomalous magnetic moments. Subsequently, new developments in our description of the nucleon excitation spectrum will be discussed, in particular a recently developed chiral effective field theory framework for the $\Delta (1232)$-resonance region. Within this framework, we discuss results on $N$ and $\Delta$ masses, the $\gamma N\Delta$ transition and the $\Delta$ magnetic dipole moment.

10 pages, prepared for proceedings of Symposium on 20 Years of Physics at the Mainz Mikrotron

References in corpus (9)

• The N to Delta electromagnetic transition form factors from Lattice QCD
• Including the $\Delta (1232)$ resonance in baryon chiral perturbation theory
• Magnetic moment of the Delta(1232)-resonance in chiral effective field theory
• Electromagnetic Nucleon-to-Delta Transition in Chiral Effective-Field Theory
• The Gerasimov-Drell-Hearn Sum Rule and the Spin Structure of the Nucleon
• Sum Rules for Magnetic Moments and Polarizabilities in QED and Chiral Effective-Field Theory
• A Derivative of the Gerasimov-Drell-Hearn Sum Rule
• Unitary model for the $\gamma p\to \gamma {\pi }^{0}p$ reaction and the magnetic dipole moment of the ${\Delta }^{+}(1232)$
• ${\gamma }^{\ast }N\Delta$ Form Factors from a Relativistic Dynamical Model of Pion Electroproduction