K photoproduction from g 11 K Hicks Ohio

K* photoproduction from g 11 K. Hicks Ohio University HSG meeting, 12 June 2009

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

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

New Data

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

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

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

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

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

New: K*+ Photoproduction • • • Analysis by Wei Tang (Ohio grad student) Using g 11 data set Detecting: p+p- pair plus another p+. Missing mass of Lambda and Sigma Acceptance using fsgen + GSIM Absolute normalization (new) – Checked using K+ photoproduction.

Details on data and cuts • • Runs 43526 – 44107 used (E=4. 02 Ge. V). 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 Ge. V.

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 Mc. Cracken).

K 0 mass peak

K*+ Mass Left s. b. Right s. b. K 0 peak minus sidebands

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

MM: one kinematic bin Eg=1. 6 -1. 7 Ge. V and -1 < cosq < -. 078

MM: higher-E bin Eg = 2. 3 -2. 4 Ge. V and -0. 11 < cosq < 0. 11

Sample fit using gaussians

gp K*+L Cross Sections Units: mb Eg (Ge. V) W (Ge. V)

Check: K 0 S+ cross sections

Previous K 0 S+ data Eg = 1. 65 Ge. V SAPHIR data (not shown) also published. B. Carnahan, Ph. D, Catholic U. (pub. in Sarantsev et al. , Eur. Phys. J. A 25, 411 (2005).

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.

Status of K*0 S+ 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!

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 L asymmetry. • Plan to have analysis note by the end of the summer. – This will be part of the Ph. D thesis of W. Tang.