Related papers: The N* Physics Program at Jefferson Lab
This review focuses on the discussion of three key results of nucleon structure calculations on the lattice. These three results are the quark contribution to the nucleon spin, J_q, the nucleon-Delta transition form factors, and the nucleon…
Recent results on nucleon resonance studies in $\pi^{+}\pi^{-}p$ electro- production off protons with the CLAS detector are presented. The analysis of CLAS data allowed us to determine all essential contributing mechanisms, providing a…
The hypercentral constituent quark model contains a spin independent three-quark interaction inspired by lattice QCD calculations which reproduces the average energy of SU(6) multiplets. The splittings are obtained with a residual…
We present results from a high precision experimental study of the nuclear modification of the longitudinal ($F_L$) to transverse ($F_1$) structure function ratio for bound nucleons in the resonance region. The inclusive electron scattering…
By extending the dynamical coupled-channels analysis performed in our previous work [Phys. Rev. C 88, 035209 (2013)] to include the available data of photoproduction of pi meson off the neutron, the transition amplitudes for the…
The charge and magnetization distributions of the proton and neutron are encoded in their elastic electromagnetic form factors, which can be measured in elastic electron--nucleon scattering. By measuring the form factors, we probe the…
We give an update on our ongoing efforts to compute the nucleon's form factors and moments of structure functions using Nf=2 flavours of non-perturbatively improved Clover fermions. We focus on new results obtained on gauge configurations…
We study the deeply-virtual Compton scattering (DVCS) process $e^- N \to e^- \gamma \pi N$ involving the transition between a nucleon and a nucleon resonance in the $\pi N$ system, within the framework of generalized parton distributions…
We develop a covariant model for the $\gamma^\ast N \to N(1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^2$ is positive. Our starting point is the covariant spectator quark model…
The covariant spectator quark model is applied to the $\gamma^\ast N \to N^\ast(1520)$ reaction. The valence quark contributions to the electromagnetic form factors and helicity transition amplitudes are estimated from the covariant…
We investigate the electric form factors of the nucleon and Roper resonance using a quark-diquark model. We find that the charge radii of the nucleon and Roper resonance are almost the same in size.
Properties of the Roper resonance, the first scalar excitation of the nucleon, are determined. Pole positions and residues of the $P_{11}$ partial wave are studied in a combined analysis of pion- and photo-induced reactions. We find the…
Studies of the spectrum of hadrons and their structure in experiments with electromagnetic probes offer unique insight into many facets of the strong interaction in the regime of large quark-gluon running coupling, {\it i.e.} the regime of…
Hadron spectroscopy has been an essential part of the physics program with the CLAS detector in experimental Hall B at Jefferson Lab. Production of baryon and meson resonances with high energy (polarized) electron and photon beams was…
Status, open questions, and future prospects of the physics of excited nucleons are discussed. Emphasis is on the study of the structure of nucleons via measurements of their electromagnetic transition form factors, the search for "missing"…
Nucleon form factors play an especially important role in studying the dynamics of nucleons and explicit structure of the wave functions at arbitrary nucleon velocity. The purpose of the paper is to explain theoretically all four nucleon…
Solutions SP00, SM00 and FA00 of nucleon-nucleon (NN) phase shift analyzes by Arndt et al. are used in optical model studies. The partial waves, single channels J.leq.7 and coupled channels J.leq.6, are scrutinized. The radial probability…
We investigate the helicity amplitudes of the $N(1520)$ and $N(1535)$ resonances in the electromagnetic transition process $\gamma^*p\to N^*$, where the $N(1520)$ and $N(1535)$ are assumed to include both the $L=1$ three-quark and $L=0$…
The electromagnetic excitation of the nucleon resonances is studied in the framework of Constituent Quark Models. Particular attention is devoted to the transition to the $\Delta$ resonance and to the issue of a possible deformation of…
I give an overview on experimental studies of the spectrum and the structure of the excited states of the nucleon and what we can learn about their internal structure. One focus is on the efforts to obtain a more complete picture of the…