1. K* photoproduction from g11 K. Hicks Ohio University HSG meeting, 12 June 2009

2. OUTLINE Review of K* photoproduction data Theoretical interest Presentations of preliminary analysis (Ohio students).

3. CLAS data (2007) I. Hleiqawi et al., Phys. Rev. C 76 (2007) 039905E.

4. New Data

5. Comparison Red (open) = CLAS, Black (solid) = TAPS Note the strong forward-peaking of TAPS data at higher photon energies.

6. K* +  (CLAS preliminary) L. Guo and D. Weygand, N* 2005 Conf., hep-ex/060101. K* +  shown by the RED points, quoted with 20% uncertainty.

7. Theory calculations: K* 0  + Y. Oh and H. Kim, hep-ph/0605105. Model I (blue): no kappa form factor; Model II (red): with kappa form factor.

8. Theory comparison: K* +  Y. Oh and H. Kim, PRC 73:065202 (2006). Full calculation (solid line) K + t-channel only (dashed) Regge model (kaon trajectory)

9. Theory: a) K* + , b) K* 0  + SOLID BLUE: no kappa form factor; DASHED RED: with kappa form factor Y. Oh and H. Kim, hep-ph/0605105.

10. New: K* + Photoproduction Analysis by Wei Tang (Ohio grad student) Using g11 data set Detecting:     pair plus another  . Missing mass of Lambda and Sigma Acceptance using fsgen + GSIM Absolute normalization (new) –Checked using K+ photoproduction.

11. Details on data and cuts Runs 43526 – 44107 used (E=4.02 GeV). Bad paddles were removed. Photon identified using 1.0 ns time cuts. Particle ID from SC and tagger time cuts. Standard fiducial and vertex cuts applied. Sideband subtraction to isolate K 0 events. K* + mass cut from 0.80-0.98 GeV.

12. Details on Normalization Used gflux method to get photons. Applied “trigger efficiency” map. –Mike Williams supplied this method. Applied “dead time” correction. –INFN’s “current dependent correction” (18%) No additional correction for start counter. –Lambda decay products not needed to fire the trigger (a la Mike McCracken).

13. K 0 mass peak

14. K* + Mass Left s.b. Right s.b. K0 peak K0 peak minus sidebands

15. K*+ Missing Mass K* + peak minus Sidebands.

16. MM: one kinematic bin E  =1.6-1.7 GeV and -1 < cos  < -.078

17. MM: higher-E bin E  = 2.3-2.4 GeV and -0.11 < cos  < 0.11

18. Sample fit using gaussians

19.  p  K* +  Cross Sections E  (GeV) W (GeV) Units:  b

20. Check: K 0  + cross sections

21. Previous K 0  + data E  = 1.65 GeV B. Carnahan, PhD, Catholic U. (pub. in Sarantsev et al., Eur. Phys. J. A25, 411 (2005). SAPHIR data (not shown) also published.

22. Status of K* + analysis Preliminary differential cross sections OK. Next step: systematic studies. Just started: Lambda decay asymmetry –Statistics reduced by about ¼. Plan: –Finish cross sections (1 month) –Preliminary Lambda asymmetries (1 month) –Write analysis note by end of summer.

23. Status of K* 0  + analysis This analysis is at a similar stage. –Normalization check requires more work This is a “redo” of the published data. –I. Hleiqawi et al. (CLAS publication). Overlap with nucleon resonances –Final state requires a PWA-like analysis. –This procedure was done for Hleiqawi data, but now we have good statistics!

24. Summary K* 0 and K* + final states are nearly final. –Normalization issues took a lot of time. –Good agreement with previous data, but much higher precision. –For K* +, can also do  asymmetry. Plan to have analysis note by the end of the summer. –This will be part of the PhD thesis of W. Tang.