Unravelling the Excitation Spectrum of the Nucleon
- JLAB
The low-energy structure of QCD lies encoded in the excited states of the nucleon, a complicated overlap of many resonances. Recent Lattice calculations have confirmed the longstanding quark model predictions of many more excited states than have been identified. Reactions that probe the spectrum are clouded by effects that dress the interactions and complicate the identification of excited levels and the interpretation of their structure. Recent theoretical work has exposed dramatic effects from such dressings. On the experimental side, new complete measurements of pseudoscalar meson photo-production are being pursued at several laboratories, where here the designation of complete refers to measurements of most if not all of the 16 possible reaction observables. This has been the focus of a series of experiments at Jefferson Lab culminating in the recently completed g9/FROST and g14/HDice runs which are now under analysis. With realistic errors, the number of observables needed to constrain the production amplitude is many more than required of a mathematical solution.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1076477
- Report Number(s):
- JLAB-PHY-12-1647; DOE/OR/23177-2534
- Journal Information:
- J.Phys.Conf.Ser., Vol. 424, Issue 01; Conference: International Seminar on Strong and Electromagnetic Interactions in High Energy Collisions, 12 October 2012, Messina, Italy
- Country of Publication:
- United States
- Language:
- English
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