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S-Y-05 S.H.LeeS-Y-05 S.H.Lee
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1. Introduction
2. Theory survey
3. Charmed Pentaquark
4. Charmed Pentaquark from B decays
Physics of Pentaquarks
Su Houng LeeYonsei Univ., Korea
References: Y. Oh, H. Kim, Y. Kwon, S.H.Lee, : PRD, PLB’s S.H.Lee,k Y. Kwon : charmed pentaquark: in preparation
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Mass= 1.54 GeV , width <25 MeV , quark content= uudds
1. LEPS coll., Nakano et.al. PRL 91 012002 (2003)
Introduction
)1520(
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Verification
2. Verification by other group
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4. NA49 hep-ex/0310014
found *(1862) in - - (ddss u) with width< 18 MeV
3. CLAS finds no ++ in K+ P invariant mass
+(udud s) belongs to anti-decuplet
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I3
Y
ud
s3 8
(1232)
(1532)
(1673)
10
N ?
?
10
N(939)
(1190)
(1320)
Baryon Reprsentation
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2. Could not confirm in subsequent experiments
CDF, ZEUS, FOCUS
1. H1 collaboration (Deep Inelastic scattering)
Heavy Pentaquarks (udud c)
c(3099) was found in D* p (uudd bar(c))
with width= 12+-3 MeV
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Experimental summary
1. + controversial
mass 1540 MeV> KN threshold (1435 MeV)
2. c+ controversial
search was done with DN D*N final state (unbound)
> 2800 MeV +
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Theory review
Soliton model + Quark model(biased and limited)
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1. SU(3) soliton
2 4( ) ( )Kin Skyrme W ZL U L U L
†exp( ) 0( , ) ( ) ( )
0 1
where ( ) has 8 angles
i rU x t R t R t
R t
2. Quantizing the 8 angles, the Hamiltonian becomes
3 72 2
1 41 2
1 1ˆ ˆ' '2 2
RotA A
A A
H J JI I
10 8 8101 2
3 3,
2 2E E E E
I I
I=J Hedghog
Soliton model: original prediction (Diakanov, Petrov, Polyakov 97)
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4. Diakanov Petrov Polyakov applied it to Anti decuplet
which predicted mass= 1540, width=30 MeV
8'2 3
cN BJ
1. only SU(3) representations containing Y=NcB/3+S= Nc /3 are allowed
2. moreover, the number of states 2I+1 at S=0 or Y= Nc/3 must determine the spin of the representation through 2J+1 because I=J in the SU(2) soliton
one spin state for given representation
3. With constraint coming from WZ term Y
3T
max
1 2
3 3Y p q
3cN
Y
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1. Karlinear, Lipkin
diquark: C=3,F=3,S=0
triquark: C=3,F=6,S=1/2
Negative parity if all the quarks are in the lowest s-state
Positive parity if a relative p wave
But with this simple picture, it is not easy to understand small width
Quark models
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2. Jaffe, Wilczek
Positive parity if a relative p wave
L=0, S=1/2 L=1 J=1/2 and 3/2 (higher mass)
color 3 3 3 1
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But, a closer look revealed puzzles
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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_cY
3T
max
1 2
3 3Y p q
3cN
Y
Quantization constraint requires max
2
3 3 3cNp q
Y
1. Octet
2. Decuplet
3. Anti decuplet
(lowest representation containing s=1)
1(1, )
2cN
3(3, )
2cN
3(0, )
2cN
3cN B
Y S
Naive Solition model should fail (T. Cohen)
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3. Mass splitting in large N_c:
3 72 2
1 41 2
1 1ˆ ˆ' '2 2
RotA A
A A
H J JI I
1
10
82
8
0
1
3 1( ),
3(1)
4
2
c
c
NE E O
EN
I
E OI
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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1. SU(2) soliton+ Kaon
2. Successful for hyperon (attractive (s qbar) ) but no pentaquark (repulsive q sbar) from WZ term
2 4( ) ( )Kin Skyrme W ZL U L U L
Bound state approach for SU(3) soliton
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Summary of Solition approach for + (ududs)
1. SU(3) Soliton
Inconsistent application
2. Bound state approach
No bound +
Can not be applied to heavy pentaquark c(ududc)
predict a bound heavy pentaquark c(ududc)
ie. mass is smaller than DN continuum
Quark model also predict a bound heavy pentaquark c(ududc) but no light pentaquark +(ududs)
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Color spin interaction quark model
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1. In QCD q-q are also attractive if in color anti-triplet channel.
aq
aq
aq
bq
abc
Quark-antiquark, or Quark-Quark attaction in QCD
kiki
M SSmm
C
kiki
B SSmm
C
In perturbative QCD, 2CB=CM This term is called color spin interaction
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Color spin interaction explains hadron spectrum
In perturbative QCD 3CB=CM = 635 MeV x ( mu )2
u u d
Nucleon
Color anti-triplet
Spin index sym s=1
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Why there should be a heavy pentaquark
1. For Pentaquark L=0, S=1/2 L=1
color 3 3 3 1
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
b c
W
u D
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Baryonic decay mode of B+
1. Baryonic decay mode in hadronic language
Coupling ?Form factor?
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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
13.5MeV 750 ,
22
2
q
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
Coupling=1
c
Dp
K
Branching ratio 0.092
Total events events 19)7.0)(092.0)(108.8)(10( 479
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SummarySummary
1.1. Theory predicts no stable light pentaquark, but bound heaTheory predicts no stable light pentaquark, but bound heavy pentaquark vy pentaquark
might explain present null results
2. Baryonic decay mode of B+ can be sensibly estimated wit previously determined hadronic parameters
3. With present B+ data, can measure c from
If found the first exotic ever, will tell us about QCD and dense matter color superconductivity