Post on 30-Dec-2015
description
K* photoproduction from g11
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) 039905E.
New Data
Comparison
Red (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.