effects of thermal partons on Jpsi

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Physics of Pentaquarks
Su Houng Lee Yonsei Univ., Korea

• Introduction
• Theory survey
• Charmed Pentaquark
• Charmed Pentaquark from B decays

References Y. Oh, H. Kim, Y. Kwon, S.H.Lee,
PRD, PLBs
S.H.Lee,k Y. Kwon charmed pentaquark in
preparation
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Introduction
1. LEPS coll., Nakano et.al. PRL 91 012002 (2003)
Mass 1.54 GeV , width lt25 MeV , quark
content uudds
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Verification
2. Verification by other group
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3. CLAS finds no Q in K P invariant mass
? Q(udud s) belongs to anti-decuplet
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Baryon Reprsentation
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10
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Heavy Pentaquarks (udud c)
1. H1 collaboration (Deep Inelastic scattering)
Qc(3099) was found in D p (uudd bar(c))
with width 12-3 MeV
2. Could not confirm in subsequent experiments
CDF, ZEUS, FOCUS
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Experimental summary
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Theory review

• Soliton model Quark model
• (biased and limited)

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Soliton model original prediction (Diakanov,
Petrov, Polyakov 97)
1. SU(3) soliton
IJ Hedghog
2. Quantizing the 8 angles, the Hamiltonian
becomes
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3. With constraint coming from WZ term

• 1. only SU(3) representations containing
  YNcB/3S Nc /3 are allowed
• moreover, the number of states 2I1 at S0 or Y
  Nc/3 must determine the spin of the
  representation through 2J1 because IJ in the
  SU(2) soliton
• ? one spin state for given representation

4. Diakanov Petrov Polyakov applied it to Anti
decuplet which predicted mass 1540, width30
MeV
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Quark models
Negative parity if all the quarks are in the
lowest s-state
But with this simple picture, it is not easy to
understand small width
Positive parity if a relative p wave

• Karlinear, Lipkin
• diquark C3,F3,S0
• triquark C3,F6,S1/2

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Positive parity if a relative p wave
2. Jaffe, Wilczek
L0, S1/2 L1 ? J1/2 and 3/2 (higher
mass)
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But, a closer look revealed puzzles
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Naive Solition model should fail (T. Cohen)
1. Soliton picture is valid at large
N_c Semi-classical quantization is valid for
slow rotation ie. Valid for describing
excitations of order 1/N_c, so that it does not
mix and breakdown with vibrational modes of order
1
2. Lowest representation SU(3)_f (p,q) at large
N_c
Quantization constraint requires

• Octet
• Decuplet
• Anti decuplet
• (lowest representation containing s1)

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3. Mass splitting in large N_c
Anit decuplet octet mass splitting is mixes with
vibrational mode and inconsistent with original
assumption and has undetermined correction of
same order ? Rotation is too fast and may couple
to vibrational modes, which might be important to
excite q qbar mode, hence describing anti
decuplet state with naïve soliton quantization
might be wrong
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Bound state approach for SU(3) soliton
1. SU(2) soliton Kaon
2. Successful for hyperon (attractive (s qbar) )
but no pentaquark (repulsive q sbar) from WZ term
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Summary of Solition approach for Q (ududs)
1. SU(3) Soliton Inconsistent application
Can not be applied to heavy pentaquark Qc(ududc)
2. Bound state approach No bound Q
predict a bound heavy pentaquark Qc(ududc)
ie. mass is smaller than DN continuum
Quark model also predict a bound heavy
pentaquark Qc(ududc) but no light pentaquark
Q(ududs)
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Color spin interaction quark model
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Quark-antiquark, or Quark-Quark attaction in QCD
1. In QCD q-q are also attractive if in color
anti-triplet channel.
In perturbative QCD, 2CBCM This term is called
color spin interaction
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Color spin interaction explains hadron spectrum
Nucleon
u
u
d
Color anti-triplet
Spin index ? sym ? s1
In perturbative QCD 3CBCM 635 MeV x ( mu
)2
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Why there should be a heavy pentaquark
1. For Pentaquark
L0, S1/2 L1
2. If recombined into a D meson and Nucleon
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Summary of Theory for Pentaquark
1. The only consistent Soliton approach predict
only heavy pentaquark
2. Constituent quark model also predict only
heavy pentaquark
may explain null result for light pentaquark
Could not observe heavy pentaqurk from DN finla
state because it might be bound
Heavy pentaquark can only be observed from Weak
decay
May be from B factory? But do we have
sufficient data and can one conclude anything if
one tries?
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Anti-Charmed pentaquark from B decays
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Can we understand Baryonic decay mode of B
1. Baryonic decay mode
2. Can we explain it using Dominant hadronic
decay mode
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Baryonic decay mode of B
1. Baryonic decay mode in hadronic language
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Effective hadronic Lagrangian for heavy hadrons
Photo production of open charm, W.Liu, C.M.Ko,
SHLee (03) NPA
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Baryonic decay mode of B
1. Baryonic decay mode in hadronic language
Obtain branching ratio of
experimental measurement
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Pentaquark decay mode of B
Using hadronic interactions as before, we find
the branching ratio to be
Branching ratio 0.092
Qc
Total events
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Summary

• Theory predicts no stable light pentaquark, but
  bound heavy pentaquark
• ? might explain present null results

2. Baryonic decay mode of B can be sensibly
estimated wit previously determined hadronic
parameters

• With present B data, can measure Qc from
• ? If found the first exotic ever, will
  tell us about QCD and dense matter ? color
  superconductivity