Nuclear Physics Seminars

ics Nuclear
Tuesday, December 18, 2012
3:30 PM
Physics Building, Room 204
Peng Peng [Host: Blaine Norum]
University of Virginia
"Pseudoscalar meson photo-production from a polarized HD target for the study of N* spectrum"
ABSTRACT:
A complete characterization of the spectrum of N and Delta resonances is essential to understand the internal structure of the nucleon. Although the Constituent Quark Models(CQM) gives good predictions for resonances in low-energy region(less than 1.8 GeV). For mass states above 1.8 GeV, many of them have not been found in experiment. This discrepancy between theory and experiment can be attributed to two reasons. One reason is that most identified resonances were discovered in piN scattering; thus, the states that couple weakly to this channel will not be seen. Another reason is that the resonances are both broad and overlapping, which make them hard to identify. The photon production of pseudoscalar mesons studied in the G14 experiment gives us a chance to look at the decay channels in pi-pi-N, eta-N, K-Lamda, etc. Moreover the use of polarized beam, polarized targets, and the detection of the polarized recoil nucleon allow us to measure a large number of polarization observables. These observables will help removing the ambiguities in determining the multipoles in partial wave analysis for the identification of the undiscovered nucleon resonances.

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