CLAS N* Excitation Results from Pion and Kaon Electroproduction

The study of the structure of excited nucleon N* states using the electroproduction of exclusive reactions is important for exploring the non-perturbative strong interaction. The electrocoupling amplitudes of N* states for masses below W = 1.8 GeV have been determined from analyses of CLAS pi N, eta N, and pi pi N data at four momentum transfers Q(2) up to 5 GeV2. These studies have made it apparent that consistency of the results from independent analyses of multiple exclusive channels with different couplings and non-resonant backgrounds but the same N* electroexcitation amplitudes, is necessary to have confidence in the results. For the hadronic couplings, many high-lying N* states preferentially decay through the pi pi N channel instead of the pi N channel. Therefore, data from the KY channels alreadymeasured with CLAS will be crucial to provide an independent analysis to compare the extracted electrocouplings for the high-lying N* states against those determined from the pi N and pi pi N channels. These comparisons await the development of suitable reaction models. Starting in 2018, a program to study the structure of N* states in various exclusive electroproduction channels using the new CLAS12 spectrometer will get underway. These studies will probe the structure of these states for masses W up to 3 GeV and Q(2) up to 12 GeV2, thus providing a means to access N* structure information spanning a broad regime encompassing both low and high energy degrees of freedom.