K* photoproduction from g11

K. HicksOhio 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) 039905E.

New Data

ComparisonRed (open) = CLAS, Black (solid) = TAPS

Note the strong forward-peaking of TAPS data at higher photon energies.

K*+ (CLAS preliminary)L. Guo and D. Weygand, N* 2005 Conf., hep-ex/060101.

K*+ shown by the RED points, quoted with 20% uncertainty.

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.

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)

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.

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.

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 K0 events.• K*+ mass cut from 0.80-0.98 GeV.

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).

K0 mass peak

K*+ Mass

Left s.b.

Right s.b.

K0 peak

K0 peak minus sidebands

K*+ Missing Mass

K*+ peak minusSidebands.

MM: one kinematic binE=1.6-1.7 GeV and -1 < cos < -.078

MM: higher-E binE = 2.3-2.4 GeV and -0.11 < cos < 0.11

Sample fit using gaussians

p K*+ Cross Sections

E (GeV)

W (GeV)

Units: b

Check: K0+ cross sections

Previous K0+ dataE = 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.

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+ 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 asymmetry.

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