kaon production on the nucleon
DESCRIPTION
Kaon Production on the Nucleon. D. G. Ireland. Kaon Photoproduction. very high momentum transfer (pQCD). Baryon Summary Table (PDG 2008). Baryon Summary Table (PDG 2012). “Missing” Baryon Resonances. Resonances in Quark Models. Baryon Spectrum on the Lattice. - PowerPoint PPT PresentationTRANSCRIPT
Kaon Production on the NucleonD. G. Ireland
MENU Rome, September 30 – October 4, 2013
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Kaon Photoproduction
very high momentum
transfer (pQCD)
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Baryon Summary Table (PDG 2008)
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Baryon Summary Table (PDG 2012)
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“Missing” Baryon Resonances
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Resonances in Quark Models
Baryon Spectrum on the Lattice
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Excited state baryon spectroscopy from lattice QCD.Edwards, Dudek, Richards, Wallace Phys. Rev. D 84, 074508 (2011)
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Resonance Hunting…
Mostly done with pN scatteringMissing resonances may decay through other channels
Total Cross-sections+ differential cross-sections+ Partial Wave Analysis + ...
Meson Photoproduction Cross Sections
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Jefferson Lab
CLAS
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g*p →KY Electroproduction
p
p
proton
Hyperon is self-analysing
Cross Section:
… with electron polarization…
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g*p →KL Separated Structure Functions
D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013
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g*p →KS Separated Structure Functions
D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013
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g*p →KL Q2 Dependence
D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013
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g*p →KS Q2 Dependence
D. Carman et al. (CLAS), Phys. Rev. C 87, 025204, 2013
gp →KL Photoproduction
proton
zyx
z
y
x
g
L
zyx
p
p
. .c mK
proton
K+
Hyperon is self-analysing
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CLAS results γp→K+Λ → K+pπ-
Bonn-Gatchina Coupled Channel Analysis, A.V. Anisovich et al, EPJ A48, 15 (2012)
(Includes nearly all new photoproduction data)
M. McCracken et al. (CLAS), Phys. Rev. C 81, 025201, 2010
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CLAS results γp→K+Λ → K+pπ-
Bonn-Gatchina Coupled Channel Analysis, A.V. Anisovich et al, EPJ A48, 15 (2012)
(Includes nearly all new photoproduction data)
M. McCracken et al. (CLAS), Phys. Rev. C 81, 025201, 2010 R. Bradford et al. (CLAS), Phys.Rev. C75, 035205, 2007
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Fit to K+Λ with PDG2010 states < 2 GeV
EBAC group: Kamano, Nakamura, Lee, Sato (2012) Includes ***, **** states
PDG states insufficient to fit KΛ data
1965 1965
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Evidence for new N* states and couplings
StateN((mass)JP
PDG 2010 PDG 2012 KΛ KΣ Nγ
N(1710)1/2+ ***(not seen in
GW analysis)
*** *** ** ***
N(1880)1/2+ ** ** * **
N(1895)1/2- ** ** * ***
N(1900)3/2+ ** *** *** ** ***
N(1875)3/2- *** *** ** ***
N(2150)3/2- ** ** **
N(2000)5/2+ * *** ** * **
N(2060)5/2- *** ** ***
Bonn-Gatchina Analysis – A.V. Anisovich et al., EPJ A48, 15 (2012)(First coupled-channel analysis that includes nearly all new photoproduction data)
Ref: Scaling and Resonances in Elementary K+L Photoproduction [R.A. Schumacher and M.M. Sargsian, Phys. Rev. C 83, 025207 (2011)]
Compute coherent total amplitude:
Fit to observed angular distributions:
Test various resonance sets vs. mass
Free parameters: mass, width, couplings
Spin observables neglected Sensitive to smaller contributions to reaction
Structure appears when scaling utilised.
N* K+L Amplitude Analysis
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Linearly Polarized Photons
Diamond radiator mountedon target ladder
Radiator in goniometer
Alignment checked byobserving symmetric
“Stonehenge Plot”
Polarization determined by fit to coherent bremsstrahlung
spectrum
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FROzen Spin Target (FROST)
Target can be longitudinally or transversely polarised[See talk by Barry Ritchie]
Transversity Amplitudes
b1 = < | M | >g p
KL }g p
KL }g p
KL }g p
KL }
b2 = < | M | >
b3 = < | M | ‖ >
b4 = < | M | ‖>
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Observables
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Imaging Multi-dimensional Objects
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Imaging Multi-dimensional Objects
?
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Comparison with other measurements
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Experiment Final State W range (Gev)
S P T Ox Oz
CLAS g11KL 1.62 – 2.84 N Y N N N
KS 1.69 – 2.84 N Y N N N
LEPSKL 1.94 – 2.30 Y N N N N
KS 1.94 – 2.30 Y N N N N
GRAALKL 1.64 – 1.92 Y Y Y Y Y
KS 1.74 – 1.92 Y Y N N N
CLAS g8KL 1.71 – 2.19 Y Y Y Y Y
KS 1.75 – 2.19 Y Y Y Y Y
Comparison with other measurements
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LEPS LEPS
CLAS g8 CLAS g8
GRAAL
GRAAL
Beam Asymmetry Comparison
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Preliminary
Beam-Recoil Comparison
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Preliminary
Beam Asymmetry Comparison
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Preliminary
Summary
• CLAS has measured a large set of data involving Kaon production
• Electroproduction: • Separated structure functions• Q2 dependence – information on form factors• Needs theoretical work
• Photoproduction: • Cross sections and recoil polarizations sensitive to N* physics• Exact interpretation of N* spectrum still ambiguous
• Outlook: • More polarization data to come (electro- and photo-production)• Results from (quasi-free) neutron• Full set of observables in KL and KS in resonance region• Exciting prospect for N* physics (with results from other channels)
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