### Session GA: Progress in Baryon Spectroscopy

8:30 AM–10:18 AM, Friday, November 5, 2010
Room: Sweeny A

Chair: Curtis Meyer, Carnegie Mellon University

Abstract ID: BAPS.2010.DNP.GA.1

### Abstract: GA.00001 : Baryonic spectra from multichannel amplitudes

8:30 AM–9:06 AM

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#### Author:

Mark Paris
(The George Washington University)

Ongoing and future experiments at precision electromagnetic facilities around the world have ushered in a renaissance in hadronic reaction theory. These high-statistics experiments offer comprehensive kinematic coverage and a large number of new polarization observables -- including the exciting prospect of a complete measurement for several reactions -- and will provide stringent constraints on reaction parameterizations and models. The recent developments promise to shed new light on the physics of baryon resonance spectroscopy, providing a window into the non-perturbative regime of QCD. Though the reaction theory is a mature field, complex phenomenological and theoretical challenges remain. Phenomenologically, amplitudes must be determined in a manner consistent with unitarity while fitting a multichannel set of unpolarized and polarized observables. The {\sc said} amplitudes for $\pi N\to\pi N$ and $\pi N\to\eta N$, as a model example of such a phenomenology, are discussed in some detail and compared with other parameterizations. Efforts to enlarge the said approach to describe the photo- and hadro-production globally have recently yielded promising developments, including a simultaneous description of $\pi-$ and $\eta-$ photoproduction amplitudes. Theoretically, multichannel, unitary dynamical models have recently undergone significant developments. An overview of these approaches are considered by comparing results from several recent calculations.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.DNP.GA.1