Related papers: The N* Physics Program at Jefferson Lab
Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data resolve a long-standing puzzle of the nature of the Roper resonance, and confirm the assertion of the symmetric…
Experiments at Jefferson Laboratory, MIT-Bates, LEGS, Mainz, Bonn, GRAAL, and Spring-8 offer new opportunities to understand in detail how nucleon resonance ($N^*$) properties emerge from the nonperturbative aspects of QCD. Preliminary data…
The physics of electromagnetic excitation of nucleon resonances and of their relevance in nucleon structure studies are discussed. Preliminary data from the CLAS detector on the N-Delta(1232) transition multipoles, the helicity amplitudes…
Recent measurements with CLAS at Jefferson Lab of nucleon resonance transition form factors for several lower mass states are discussed.
The $N(1440)1/2^+$ nucleon resonance, first identified in 1964 by L.D. Roper and collaborators in analyses of $\pi N$ hadroproduction data have continued to provide pivotal insights that serve to advance our understanding of nucleon excited…
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\gamma_{v}pN^*$ transition amplitudes…
I discuss recent results on the electroproduction and photoproduction of mesons in the region of non-strange baryon resonances. Results on the quadrupole transition from the ground state nucleon to the Delta(1232) show the importance of…
This document outlines major directions in theoretical support for the measurement of nucleon resonance transition form factors at the JLab 12 GeV upgrade with the CLAS12 detector. Using single and double meson production, prominent…
The electroexcitation of the ${\cal N}^*(1440)$ Roper resonance, which defines the first radially excited state of the nucleon, is examined within the soft-wall AdS/QCD model. Such excited Fock states are characterized by the leading…
Recent results from JLab on the electromagnetic excitation of nucleon resonances are presented, and confronted with theoretical predictions. Preliminary data in the search for undiscovered states are discussed as well.
A workable basis of quark configurations $s^3$, $s^2p$ and $sp^2$ at light front has been constructed to describe the high-$Q^2$ behavior of transition form factors and helicity amplitudes in the electroproduction of the lightest nucleon…
We discuss the results on the fundamental degrees of freedom underlying the nucleon excitation spectrum and how they evolve as the resonance transitions are investigated with increasingly better space-time resolution of the electromagnetic…
The results on the photo- and electroexcitation amplitudes of most nucleon resonances in the mass range up to 2.0 GeV determined from the CLAS experimental data on exclusive $\pi^+\pi^-p$ photo-/electroproduction off protons in…
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited…
Studies of the nucleon resonance electroexcitation amplitudes in a wide range of photon virtualities offer unique information on many facets of strong QCD behind the generation of all prominent excited nucleon states. Advances in the…
In a relativistic quark model we study the structure of the $N(1710)$ resonance, and the $\gamma^\ast N \to N(1710)$ reaction focusing on the high momentum transfer region, where the valence quark degrees of freedom are expected to be…
A covariant spectator quark model is applied to estimate the valence quark contributions to the$ F1*(Q2) and F2*(Q2) transition form factors for the gamma N -> P11(1440) reaction. The Roper resonance, P11(1440), is assumed to be the first…
Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of…
We report on the low and moderate Q^2 nucleon spin structure measurements done at Jefferson Lab, examining specifically the inclusive program. We discuss what the data teach us about quark confinement and the emergence of the effective…
We present calculations of $\gamma^\ast N \to N^\ast$ transition form factors, where $N$ is the nucleon and $N^\ast$ is a nucleon resonance, based on a covariant quark model. Our main focus is at high photon virtualities (large $Q^2$) where…