N⁎ program at CLAS

The N⁎ program is one of the major goals of CLAS experiments in Jefferson Lab and many outstanding results have been carried out. In this note, I will present some highlight recent measurements of nucleon resonance transition form factors from electro-production as the second resonances. The new pion electro-production data resolve a longstanding puzzle of the nature of the Roper resonance, and confirm the assertion of the symmetric constituent quark model of the Roper as the first radial excitation of the nucleon. The single pion electro-production data for high Q2 confirms the slow fall off of the S11(1535) transition form factor with Q2, and better constrain the branching ratios βNπ:βNη=0.50:0.45. For the first time, the longitudinal transition amplitude to the S11(1535) was extracted from the nπ+ data. Also, new results on the transition amplitudes for the D13(1520) resonance are presented showing a rapid transition from helicity 3/2 dominance seen at the real photon point to helicity 1/2 dominance at higher Q2.