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Title: CLAS N* Excitation Results from Pion and Kaon Electroproduction

Abstract

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.

Authors:
ORCiD logo [1]
  1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP)
Contributing Org.:
CLAS Collaboration
OSTI Identifier:
1440325
Report Number(s):
JLAB-PHY-18-2610; DOE/OR/23177-4305
Journal ID: ISSN 0177-7963; PII: 1405; TRN: US1900715
Grant/Contract Number:  
AC05-06OR23177
Resource Type:
Accepted Manuscript
Journal Name:
Few-Body Systems
Additional Journal Information:
Journal Volume: 59; Journal Issue: 5; Journal ID: ISSN 0177-7963
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Electromagnetic interactions; Form factors; Nucleon structure; Excited nucleon states

Citation Formats

Carman, Daniel S. CLAS N* Excitation Results from Pion and Kaon Electroproduction. United States: N. p., 2018. Web. doi:10.1007/s00601-018-1405-8.
Carman, Daniel S. CLAS N* Excitation Results from Pion and Kaon Electroproduction. United States. doi:10.1007/s00601-018-1405-8.
Carman, Daniel S. Thu . "CLAS N* Excitation Results from Pion and Kaon Electroproduction". United States. doi:10.1007/s00601-018-1405-8. https://www.osti.gov/servlets/purl/1440325.
@article{osti_1440325,
title = {CLAS N* Excitation Results from Pion and Kaon Electroproduction},
author = {Carman, Daniel S.},
abstractNote = {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.},
doi = {10.1007/s00601-018-1405-8},
journal = {Few-Body Systems},
number = 5,
volume = 59,
place = {United States},
year = {2018},
month = {5}
}

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Figures / Tables:

Fig. 1 Fig. 1: Schematic representation of the $γ$N → N electroproduction process. (a) The fully dressed $γ$$v$$NN$ electrocoupling that determines the $N$ contribution to the resonant part of the meson electroproduction amplitude. (b) The contribution of the three-quark core. (c) The contribution from the meson-baryon cloud, where the sum is overmore » all intermediate meson and baryon states. This figure was taken from Ref. [8].« less

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    Works referencing / citing this record:

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    Spectrum and structure of octet and decuplet baryons and their positive-parity excitations
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      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.