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• Baryon resonances Quark model description ( deformed oscillator ) KN for L (1405) ~ importance of qq correlation qq vs qq Chiral symmetry • Pentaquarks Full 5-body calculation ~ qq Production of Q + ~ consistency of J-Lab and LEPS. - PowerPoint PPT Presentation
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Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 1
Hadron spectroscopy Pentaquarks and baryon resonances
Atsushi Hosaka, RCNP Osaka Univ.
• Baryon resonances Quark model description (deformed oscillator) KN for(1405) ~ importance of qq correlation qq vs qq Chiral symmetry
• Pentaquarks Full 5-body calculation ~ qq Production of + ~ consistency of J-Lab and LEPS
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 2
At low energiesLattice QCD does a lot: Masses, Form factors, Resonances, (Interactions) qq potential, Vacuum properties Exotics (pentaquarks,…)?
Are there simple way to understand them? Global/local symmetry and its breaking Relevant degrees of freedom, effective interactions ElementaryExcitation of non-perturbative vacuum (Kunihiro)
=> Models of QCD hopefully with one or at most few
But current understanding is not at this level
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 3
Simple setups:
• SU(6) and small ms breaking • Harmonic oscillator potential, V(r) = kr2
• Effective residual interaction Gluons, Chiral mesons, instantons, …
Let us start with Quark model
To test the quark model, let us see baryon states
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 4
Light flavor (uds) baryons
Well established states
49 ***,**** states out of 5013 * , ** states out of 31
62 states out of 81 states
2500
2000
1500
1000
N Σ Δ Ξ
But if we rearrange
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 5
Positive parity baryons
2000
1500
1000
500
028 S
28 S28 S
410 S410S
N Σ Δ
P11 (1440)
F15 (1680)
P13 (1720)
H19 (2220)
P11 (1710)P01 (1600)
F05 (1820)
P03 (1890)
H09 (2350)
P01 (1810)
F05 (2110)
P11 (1660)
F15 (1915)
*P13 (1840)
F17 (2030)
*F15 (2070)
**P13 (2080)
P33 (1600)
F37 (1950)
F35 (1905)
P33 (1920)
P31 (1910)
H311 (2420)
P11 (939) P01 (1116) P11 (1189) P13 (1385) P33 (1232)
=0
=0
=2
=4
** P13 (1900)
** F17 (1990)
** F15 (2000)
*F07 (2020)
** F37 (2390)
** P11 (1880)
8MΣ 8 MΣ28 MΣ
• Measured from the ground state • 8MS states are shifted downward by 200 MeV
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 6
Negative parity baryons
• Measured from the 1/2+ ground state • 48MS states are shifted downward by 200 MeV
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 7
Deformed Oscillator Model
• Ground state: spherical • Excited states:
Single particle excitation deforms the confining potential Deformed states rotate collectively => Resonances as collectively rotated states
Takayama-Toki-HosakaProg.Theor.Phys.101:1271-1283,1999
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 8
It seems that we make a good job
Important questions:
BUT: Is this the end of the story???
Roper as a diquark states => Nagata • Quark correlations qq or qq
• Also qqq* states can mix with qqq(qq)
L(1520) as a KN state => Hyodo
• Chiral symmetry
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 9
Role of qq (meson)correlation
Long time being said, but renewed interests due to chiral perturbation and its unitarization
Interaction Resonance
Basic assumptions: Ground state hadrons as building blocks: B and M Contact MB interaction dominates the s-wave dynamics
L Tomozawa-Weinberg
Meson clouds
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 10
(1405)
Two poles near Mass ~ 1405
Σ ->Σ ->Σ
1426 + 16i (KN)
1390 + 66i (Σ)
K–p –> Σ, Magas-Oset-Ramos, Phys.Rev.Lett.95:052301,2005
Jido-Oller-Oset-Ramos-Meissner, Nucl.Phys.A725:181-200,2003: nucl-th/0303062
The state is crucially important for the K-nuclei
KN ~ 8 x 8 = 1, 8, 8, 10, 10, 27attractive repulsive
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 11
In the quark language
qq-correlation vs. qq-correlation
Color-spin interaction
qq(C, S) (3*C, 0S) (3*
C, 1S) (6C, 0S) (6C, 1S) –1/2 +1/6 +1/4 –1/12
qq(C, S) (1C, 0S) (1C, 1S) (8C, 0S) (8C, 1S) –1 +1/3 +1/8 –1/24
qq correlation is equally or more important than qqfor equal masses. If m>>m, then qq is suppressed
To see qq correlations, heavy quark systems may be suited
€
VCS = −ij∑ k
mim j
λa (i)2
λa ( j)2
r σ (i) ⋅ r
σ ( j)
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 12
Chiral symmetry
Conventional wisdom:
• Chiral symmetry is spontaneously broken • <qq> condenses • Quarks couples to <qq> and obtain a constituent mass
Questions:
• What is the coupling of hadrons to <qq> ~ Hadron mass • What are chiral (parity) partners • What is the realization of chiral symmetry
Linear vs. non-linear
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 13
They are related to:
How far our world is from the symmetric worldHow strongly chiral symmetry is broken
Large f , mSmall f , m
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 14
If symmetry breaking is not very large=> Particles in chiral group representations
SU(2)L x SU(2)R
Baryons: (1/2, 0), (1, 1/2), (3/2, 0), ….
Mesons: (0, 0), (1/2, 1/2), (1, 0), …
• For baryons, chiral partners can be made by Particles of the same parity (N, Δ, R) S. Weinberg, Phys.Rev.177:2604-2620, 1969 Particles of opposite parities (N, N*) Jido-Hosaka-Oka, Prog.Theor.Phys.106:873-908,2001 Jido-Hatsuda-Kunihiro, Phys.Rev.Lett.84:3252,2000
with mixings
, a1
N N, Δ, Δ,
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 15
• gA ~ 1.25 close to 1 => N ~ (1/2, 0) + (1, 1/2)
• Masses of chiral partners degenerate as symmetry recovers
€
MN
€
q q = 0
€
q q ≠ 0
€
MN *
• There could be N* of gA < 0
BUT we need morestudies to clarify the role of chiral symmetry
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 16
Pentaquarks
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 17
Most serious calculation for 5-body system with scattering states included Gaussian expansion method
+-confined NK-scattering
+
Compute phase shifts
qq qq
5-body calculation for +
Hiyama et al, hep-ph/0507105
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 18
NR quark model of Isgur-Karl
Hamiltonian
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 19
Eres ~ 530 MeVres ~ 110 MeV
• Mass is too high • Strong qs correlation –> JW configuration is suppre
ssed
Diquark formation is a dynamical problem
KN-phase shifts 1/2+
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 20
Production
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 21
J-Lab
QuickTime˛ Ç∆TIFFÅiLZWÅj êLí£ÉvÉçÉOÉâÉÄ
ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
p –> n K+ K0
CLAS g11
Preli
minaryg10
d --> K+ K- p (n)
?
LEPS n -> n K+ K– d -> K+ K– p n
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 22
J-Lab
LEPSBeam line
LEPS: forward angle regionCLAS: side
LEPS has observed but CLAS does not
Observation 1
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 23
• Large p, n asymmetry
(Charge exchange) >> (Charge non-exchange)
Nam-Hosaka-Kim, hep-ph/0503149, PRD, 71:114012,2005 hep-ph/0505134
Observation 2
• Strongly forward peaking
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 24
present only for charge exchange
Effective Lagrangian approach
s u
tcontact
n –> + or p –> (1520)
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 25
n -> K– (1520) and p -> K0 (1520)
was studied and large pn asymmetry was known to usNam-Hosaka-Kim, hep-ph/0503149 to appear PRD
Energy dependence
Before the -production
t (or ) dependence
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 26
Contact term • Large pn asymmetry • Strong forward peak • Polarization??
= 700 MeV <=> r ~ 0.8 fm
To be checked byexperiments
(1520) JP = 3/2–
p –> K+ (1520) Charge exchange
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 27
• Large pn asymmetry • If + is larger in size,
may be smaller and strongly forward peaking• ~ few nb or less -> consistent with the CLAS result
=1MeV= 700 MeV <=> r ~ 0.8 fm
The total cross section is very sensitive to
For + n –> K– + Charge exchange
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 28
Summary • Hadrons seem to need different ingredients:
constituent quarks, diquarks, mesons, chiral symmetries.
• Perhaps we need a simple setup having a predictive power, consistent with QCD, and explaining ground to resonant states, decay/productions,…
• Pentaquarks may still survive, which should be explained by the same setup
• Experimentally: exotics containing multi-quarks and antiquarks are good laboratory to study the relevant questions.
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 29
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 30
Why hadrons?
• The core of matter (made of atoms)
• Strongly interacting quantum system of QCD
• Rich aspects in phase structure
They are based on:hadron structure and reactions from quarks (QCD)
Everybody knows that:
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 31
But not so easyDue to non-perturbative dynamicsColor confinement and chiral symmetry breaking
Is it possible to describe hadron properties? Can we predict masses, form factors, decay/production rates and so on?
Can we predict unknown states prior to experiment?
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 32
Total
Angular dist
Log-
scal
e
neutron ~ forward peak Contact term
proton ~ rather flatLog-
scal
e
Theta production, JP = 3/2
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 33
Mass Magnetic moments Charge radii
Good for conventional baryons
Nov. 30 - Dec. 2, 2005
J-PARC workshop, KEK 34
LEPS: deuteron -> (Theta, L(1520))
• Reaction mechanism Soft K?
We need to understand
d
(1520)
K
NMNK
• Elementary process +, (1520) production
• Consistency between the J-Lab experiment