Photoproduction of Q on the nucleon and deuteron

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Photoproduction of Q on the nucleon and deuteron

• T. Mart
• Departemen Fisika FMIPA
• Universitas Indonesia, Depok 16424, Indonesia

Work in colaboration with Cornelius Bennhold and
Agus Salam (George Washington) (Okayama)
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Contents

• Photoproduction of Q on the nucleon
• Feynman diagram
• Predicted cross sections
• Regge description
• Photoproduction of Q on the deuteron

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Photoproduction of Q on the nucleon

• Two processes considered

connected by isospin formalism
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StandardFeynman diagram
no resonance considered

• Decompose into

write down the amplitudes in terms of M1 M4
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to obtain the A1 A4
gauge inv. hadronic FF H. Haberzettl et al. PRC
58, R40 (1998)
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coupling constants and magnetic moment for Q
Use isospin symmetry to relate
coupling constants decay widths 21 MeV
(Stepanyan et al) to derive gKQN
magnetic moment from soliton model (H.C.
Kim, hep-ph/030824)
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coupling constants for K
Some information from K radiative decay
widths gK0K0g / gK-K-g
Soliton model (M.V. Polyakov private comm.)
SU(3) H. Thom, PRC151, 1322 (1966)
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Total cross sections without K exchange

• Insensitive to mag. moment for neutron channel
• Relatively sensitive in proton channel

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Total cross sections with K exchange

• K coupling from Soliton model (Polyakov private
  comm.)
• Large variation in total CS for 10 variation of
  CC
• Information about K coupling is crucial here

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Total cross sections with different cut-off

• Large variation with only 10 change in the
  cut-off
• Experiences in gp? KL and gp? KS
• cut-off 0.7 GeV
• ? smaller CS probable

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differential cross sections n p channels

• different shape due to absence of t-channel in g
  p ? K0 Q

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differential cs and variation K cc

• g p ? K0 Q
• Contributionand variation mostly in forward
  directions

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differential cs and variation K cc

• g n ? K- Q
• Almost similar to
• g p ? K0 Q

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differential cs and variation of cut-off

• Uniform variation

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differential cs and variation of cut-off

• Backward peaking due to the absence of t-channel
  (K)
• uniform variation

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Regge description

• Simpler than isobar model, only t-channels
  electric term of s-channel ? gauge invariance M.
  Guidal et al., NPA 67, 645 (1996)
• Works nicely for gp ? KL and gp ? KS
• Simple Regge propagator
• with trajectories a(t)

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Regge trajectories
K
K
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Results for neutron channel (Regge)
Shape similar to gp ? KL
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Results for proton channel (Regge)
Shape similar to gp ? KS
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Total cross section (Regge)
smaller than Feynman approach
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Photoproduction of Q on the deuteron
elementary operator from g N ? K Q
Work in progress With Agus Salam
Bonn potential
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Total cross section on the deuteron
Including K Maintain the CS shape, but smaller
(almost ½)
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Total cross section on the deuteron

• We have calculated predicted cross sections for
  Q photoproduction on the nucleon and deuteron
• Cross sections are relatively smaller than in the
  case of KL or KS photoproduction
• Regge formalism predicted smaller CS
• Information on K coupling(s) and hadronic
  cut-off is crucial