The C arnegie M ellon U niversity Program for Studying Baryon Resonance Photoproduction

1. The Carnegie Mellon University Program for Studying Baryon Resonance Photoproduction using Partial Wave Analysis Mike Williams Curtis Meyer Matt Bellis Reinhard Schumacher Zeb Krahn Doug Applegate N* 2005 FSU October 12-15

2. Talk Outline Program Goals A Look at Our Data Covariant Tensor Formalism PWA Fitting Procedure www-meg.phys.cmu.edu/pwa Fit Output Where we’re headed

3. Program Goals Our Goal: Study the Baryon Spectrum by Performing a Partial Wave Analysis on the following channels γ p→ p ππ γ p→ pω γ p→ pη N* Filters www-meg.phys.cmu.edu/pwa γ p→ pη’ γ p→ K Λ γ p→ K Σ start analysis soon We’re Looking for Missing Baryons

4. The Data Our data was taken using the CEBAF Large Acceptance Spectrometer located at Jefferson Lab www-meg.phys.cmu.edu/pwa

5. The Data γ p→ pω γ p→ pη www-meg.phys.cmu.edu/pwa Dalitz plot for γ p→ p ππ

6. Formalism Covariant Tensor Formalism (Anisovich,Laget,…) u(p,m) εμ(p,m),… γμγ5 … Include terms for s,t,u and contact terms www-meg.phys.cmu.edu/pwa use regge trajectories for t-channel Software: C++ Code (see Doug Applegate’s Poster)

7. Fitting Procedure Un-binned Maximum Likelihood Method in each W-bin Event by Event (we do NOT fit to cross sections) Couplings and Fit Parameters www-meg.phys.cmu.edu/pwa Mass Independent Fit (only use BW’s in daughter decays) We fit to intensity and phase of each wave

8. Fit Output Fit gives contribution of each wave in each W-bin Ex.) γ p→ pη (8 free parameters) www-meg.phys.cmu.edu/pwa

9. Coupled Channel γ p→ pη Different Acceptance and Systematics γ p→ pη’ γ p→ p ππ www-meg.phys.cmu.edu/pwa Use omega as N* filter γ p→ pω

10. Where we’re headed Right now we’re working out Experimental Issues Amplitude generation and Fitting code is up and running We’ve run extensive test fits already www-meg.phys.cmu.edu/pwa Preliminary results in some channels should be ready soon!