CLAS N* Excitation Results from Pion and Kaon Electroproduction

Journal Article · 23 May 2018 · Few-Body Systems

DOI: https://doi.org/10.1007/s00601-018-1405-8 · OSTI ID:1440325

Carman, Daniel S.  ^[1]

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1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

The study of the structure of excited nucleon $N^*$ states employing the electroproduction of exclusive reactions is an important avenue for exploring the nature of the non-perturbative strong interaction. The electrocouplings of $N^*$ states in the mass range 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~GeV$^2$. The work has made it clear that consistent results from independent analyses of several exclusive channels with different couplings and non-resonant backgrounds but the same $N^*$ electroexcitation amplitudes, is essential to have confidence in the extracted results. In terms of hadronic couplings, many high-lying $N^*$ states preferentially decay through the $$\pi \pi N$$ channel, while couplings to $$\pi N$$ final states become rather small. The resonance parameters determined from $$\pi N$$ and $$\pi \pi N$$ electroproduction can be checked in independent studies of the $KY$ ($$Y = \Lambda, \Sigma^0$$) channels. Therefore, data from the $KY$ channels already measured with CLAS will play an important role in $N^*$ structure studies. 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 $N^*$ states in the mass range up to $$W$$=3~GeV and $Q^2$ up to 12~GeV$^2$, thus providing a means to access $N^*$ structure information spanning a broad regime encompassing both low- and high-energy degrees of freedom.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
• Contributing Organization: CLAS Collaboration
• Grant/Contract Number: AC05-06OR23177
• OSTI ID: 1440325
• Alternate ID(s): OSTI ID: 22733253
• Report Number(s): JLAB-PHY-18-2610; DOE/OR/23177-4305; PII: 1405
• Journal Information: Few-Body Systems, Journal Name: Few-Body Systems Journal Issue: 5 Vol. 59; ISSN 0177-7963
• Publisher: SpringerCopyright Statement
• Country of Publication: United States
• Language: English