Related papers: The N* Program at Jefferson Lab - Status and Prosp…
Recent results on inclusive and exclusive electroproduction experiments at Jefferson Lab are discussed. They include measurements of the spin responses for protons and neutrons in and above the resonance region, exclusive single and double…
We present results on the electroexcitation of the low mass resonances Delta(1232)P33, N(1440)P11, N(1520)D13, and N(1535)S11 in a wide range of Q2. The results were obtained in the comprehensive analysis of JLab-CLAS data on differential…
Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the…
The process $ep \to e^{\prime}p^{\prime}\pi^0$ has been measured at $Q^2$ = 6.4 and 7.7 GeV/c$^2$)$^2$ in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center of mass frame…
We report new pion electroproduction measurements in the $\Delta(1232)$ resonance, utilizing the SHMS - HMS magnetic spectrometers of Hall C at Jefferson Lab. The data focus on a region that exhibits a strong and rapidly changing interplay…
Impressive progress achieved in the past decade in experimental studies of exclusive meson photoproduction off protons and global multi-channel amplitude analyses has resulted in the discovery of several long-awaited new nucleon resonances,…
Studies of the structure of excited baryons are key to the N* program at Jefferson Lab. Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N*…
All the time since its discovery the N$^*$(1440) baryon state, commonly known as Roper resonance, has been a state with many question marks - despite of its 4-star ranking in the particle data book. One reason is that it does not produce…
The transition helicity amplitudes from the proton ground state to the $N(1440)1/2^+$, $N(1520)3/2^-$, and $\Delta(1620)1/2^-$ resonances ($\gamma_vpN^*$ electrocouplings) were determined from the analysis of nine independent one-fold…
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…
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 unitary isobar model MAID2007 has been used to analyze the recent data of pion electroproduction. The model contains all four-star resonances in the region below W=2 GeV and both single-Q^2 and Q^2 dependent transition form factors…
We review recent progress in our understanding of the nucleon excitation spectrum. Thanks to dedicated efforts at facilities such as ELSA, MAMI and Jefferson Lab, several new nucleon resonances have been discovered, and evidence for…
The study of hyperon resonances has entered a new era of precision with advent of high-statistics photoproduction data from the CLAS detector at Jefferson Lab. These data have multi-particle final states, allowing clean identification of…
Pion scattering and electro-production amplitudes have been computed in a coupled-channel framework incorporating quasi-bound quark-model states, based on the Cloudy Bag model. All relevant low-lying nucleon resonances in the P33, P11, and…
The analysis of the nine 1-fold differential cross sections for the $\gamma_{r,v} p \to \pi^+\pi^-p$ photo- and electroproduction reactions obtained with the CLAS detector at Jefferson Laboratory was carried out with the goal to establish…
We summarize the physics topics which can be addressed by measurements of high-Q^2 exclusive electroproduction of strange mesons, gamma* N -> phi N, K* Lambda, K Lambda, K Sigma, at Jefferson Lab with 11 GeV beam energy. The proposed…
The double pion photoproduction off nucleons near threshold is analyzed in a covariant baryon chiral perturbation theory up to next to leading order, where the $\Delta(1232)$, $N^*(1400)$ and $\rho(770)$ resonances are included as explicit…
Advances in the exploration of the spectrum and structure of the excited states of the nucleon from experiments with electromagnetic probes on proton targets are presented. Impressive progress has been achieved in the studies of exclusive…
A model for the gamma p ----> pion+ pion- p reaction developed earlier is extended to account for all isospin channels. The model includes N, Delta(1232), N^*(1440) and N^*(1520) as intermediate baryonic states and the rho-meson as an…