Abstract
We report on a recent calculation of all Roper-related electromagnetic transtions form factors, cov ering the range of energies that next-to-come planned experiments are expected to map. Direct reliable cal culations were performed, within a Poincaré covariant approach of the three-body bound-state problem, up to Q2/m2N=6; approximated then by applying the Schlessinger point method and the results eventually extended up to Q2/m2N ≃12 via analytic continuation.
Highlights
Albeit there is no doubt about the nature of nucleons as bound states made of three valence-quarks, that of their first excited states – N(1440) 1/2+, N(1535) 1/2− – is less certain
Direct reliable calculations were performed, within a Poincaré covariant approach of the three-body bound-state problem, up to Q2/m2N=6; approximated by applying the Schlessinger point method and the results eventually extended up to Q2/m2N 12 via analytic continuation
During the last 20 years, a combined effort for the acquisition of a vast amount of high-precision proton-target exclusive electroproduction data, for their analysis with sophisticated tools from dynamical reaction theory, and for the formulation of wide-ranging application of a Poincaré covariant approach to the continuum bound-state problem in quantum field theory led to the wide acceptance about the Roper being the first radial excitation of the nucleon [7]
Summary
Albeit there is no doubt about the nature of nucleons as bound states made of three valence-quarks, that of their first excited states – N(1440) 1/2+, N(1535) 1/2− – is less certain. The high-Q2 electroproduction data were crucial to reaching this understanding of the Roper and, with a new era of experiments beginning at the upgraded JLab in the near future, are expected to sharpen the contemporary picture for the Roper resonance by fostering a unified explanation of elastic and transtion form factors for nucleons, ∆-baryon and Roper resonances. To pursue this goal, given that JLab 12 will deliver results for the Q2dependence of R0,+ electrocouplings, reaching to Q2 ≈. We will sketch these calculations, grounded on the framework of many previous Poincaré-covariant continuum analyses of the three valence-quark bound-state problems associated with the nucleon, ∆-baryon and Roper resonance [12,13,14,15,16,17,18]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
