Speaker
Description
An experimental program has been approved at the Thomas Jefferson National Accelerator Facility to measure the (ep,e’K+)Y reactions to study the spectrum and structure of excited nucleon states. New data from CLAS12 on πN, ππN, and KY electroproduction have been obtained using electron beams with energies of 6.5 and 7.5 impinging upon a liquid hydrogen target. Scattered electrons have been detected in a polar angle range of 2.5° to 4.5° by the Forward Tagger (FT) and at angles greater than 6° in the CLAS12 Forward Detector, allowing to measure the KY electro-production differential cross section and to probe the Q2 evolution of the nucleon resonances electro-couplings in the Q2 range from 0.05 GeV2 to 3 GeV2. The Q2 dependence of excited baryons electro-couplings allows to probe the dressed quark mass over the full range of distances where the dominant part of hadron mass emerges from QCD. By studying the Q2 evolution of electroexcitation amplitudes it will be also possible to distinguish between regular N states and possible additional hybrid baryon states in the mass range of 2.0 GeV < W < 2.5 GeV where the lightest hybrid baryons are expected to be located based on LQCD studies of the N* spectrum.
Preliminary results for KY electroproduction will be reported and prospects for future studies will be discussed.
