Production of charmed baryons -- Rough estimate --
description
Transcript of Production of charmed baryons -- Rough estimate --
Production of charmed baryons-- Rough estimate --
Atsushi Hosaka, RCNP (Osaka U)
• Rate for charm and strange productions Effective Lagrangian and Regge
• Production of various baryons states Quark-diquark model
12/03, 2012 JPARC-Collab 1
Charm and strange productions
12/03, 2012 JPARC-Collab 2
• We do not know much about charm production
• Use an appropriate model for strange production from medium to high energy
• Kinematically extend the model to the charm region
Effective Lagrangian and/or Regge
Strategy
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1
10–1
10–2
101
ωφ
J/ψ
ρ
Total γp Vp
W [ GeV]
102
μb
102101
~ 100
About 100 times smaller than strangeness production
What about for the pion induced reaction
Effective Lagrangian
12/03, 2012 JPARC-Collab 4
• Four possible processes; s, t, u and contact• At high energies and forward region, t-dominates s: suppressed, no resonance above 3 GeV u: suppressed kinematically c: unknown
• D, D* exchanges allowed, but scalar is not
π
NN
D*
D-exchange
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π
NN
D*
D
0.5 0.7 0.9 1.1 1.3 1.50.00
5.00
10.00
15.00
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 10
10
20
30
40
50
k (cm) GeV
π+P ρ+p Light flavor, u,d
F1: 8 mb
F2: 7 mb
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 10
0.05
0.1
0.15
0.2
k (cm) GeV
π+P K*+Λ(1116)
0.7 0.9 1.1 1.3 1.5 1.70
0.05
0.1
0.15
0.2
Strangeness
F1: 8 mb ------> 0.07 mb
F2: 7 mb ------> 0.04 mb 1/120
1/170
k (cm) GeV
π+P D*+Λc(2226)
2 2.5 31E+00
1E+02
-1 -0.5 0 0.5 11E-08
1E-07
1E-06
1E-05
1E-04
1E-03
1E-02
1E-01
Charm
F1: 8 mb ------> 0.07 mb ------> 0.0006 mb
F2: 7 mb ------> 0.04 mb ------> 0.00002mb = 20pb1/120 1/120
1/170 1/2000
Regge's mechanism -- Brief idea --
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Resonances K*, … can be exchanged
No resonance exists with Q = 2 t-channel
×
○
t-channel amplitude
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lt = 0, 1, 2, …
For l = σ
This violates unitarity Need to sum over all l
Regge's method
Regge trajectoryForm factor~ forward peak
0 < t Physical particle region
t < 0Scattering region
Regge trajectory
Features
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• Determines the asymptotic behavior s ∞• Gives forward peak (diffractive pattern)• Agrees well with high energy scattering data ~ few hundred MeV above the strangeness threshold
BUT difficult to determine• Absolute production rates• Form factors (t-dependence)
Therefore, we may use• For relative production rate• At forward angle
Vector vs Pscalar trajectory
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Vector >> Pscalar at large s
Vector Reggeon, some model dependence
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• Naïve Regge
• Kaidalov
This is partly regarded as ambiguity in s0
• Grishina
• Kaidalov
1E+00 1E+011E-05
1E-04
1E-03
1E-02
1E-01
1E+00
1E+01
1E+02
1E+03σtot [μb] Naïve-Kaidalov
Grishina
KaidalovNaive
Strange
Charm
Vector Reggeon, some model dependence
Grishina
Production of Bc in a quark-diquark model
12/03, 2012 JPARC-Collab 17
Quark-diquark baryonSelem-Wilczek: e-Print: hep-ph/0602128
• ee has repulsive force, BUT• qq has attractive force SU(3)c :half of qqbar attraction SU(2)c : Same as qqbar Pauli-Gursey symmetry ~ several hundred MeV
• Diquark can be seen better in heavy baryons
Color magnetic int.Good Bad
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d
Q
λ-mode
Pion induced charm production
λ-mode baryons
• D*-exchange couples to various B's lλ = 0, 1, 2 (18 baryons)• Estimate forward scattering strength ~ Regge shows• State dependence (ratio) is estimated by qd model
Transitions to Qd baryons
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λ
N(1/2+) Bc(JP)
Forward
Computation of matrix elements
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1
Baryon wave functions
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Orbital
Spinχρ S=1/2 of good d (S = 0) + cχλ S=1/2 of bad d (S = 1) + cχS S=3/2 of bad d (S = 1) + c
Isospin Similar to spin WF
Nucleon
Charmed baryons
Radial matrix elements IL
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Results
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1.00 0.02 0.16
0.90 1.70 0.02 0.03 0.04 0.19 0.18
0.50 0.88 0.02 0.02 0.01 0.03 0.07 0.07
Charm kπ = 2.71 [GeV]
Results
Strange kπ = 1.59 [GeV]
1.00 0.067 0.44
0.11 0.23 0.007 0.01 0.01 0.07 0.067 0.13 0.20 0.007 0.01 0.004 0.02 0.038 0.04
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1.00 0.02 0.16
0.90 1.70 0.02 0.03 0.04 0.19 0.18
0.50 0.88 0.02 0.02 0.01 0.03 0.07 0.07
Charm kπ = 2.71 [GeV]
Summary
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• Regge approach: R(c)/R(s) = 1/100 – 1/1000• Forward peak
• Qd model shows spin-dependent rate• Some higher L states may have large production rate comparative to the ground state