International Symposium on Clustering
as a Window on the Hierarchical Structure of Quantum Systems(CLUSHIQ2022) 2022.11.01

Elucidation of hierarchical structure
between quark and hadron phases
utilizing quark clusters

Hiroaki Ohnishi
ELPH, Tohoku University1

International Symposium on Clustering
as a Window on the Hierarchical Structure of Quantum Systems(CLUSHIQ2022) 2022.11.01

Elucidation of hierarchical structure
between quark and hadron phases
utilizing quark clusters
A challenge to reveal new degrees of freedom to describe hadron

Hiroaki Ohnishi
ELPH, Tohoku University1

International Symposium on Clustering
as a Window on the Hierarchical Structure of Quantum Systems(CLUSHIQ2022) 2022.11.01

Elucidation of hierarchical structure
between quark and hadron phases
utilizing quark clusters
A challenge to reveal new degrees of freedom to describe hadron
Summary and perspective from A02 project

Hiroaki Ohnishi
ELPH, Tohoku University
1

The hierarchical structure of matter

2

The hierarchical structure of matter• Our gourd (A02) is focusing on“Hadron” to reveal and understandthe hierarchical structure of matter

2

The hierarchical structure of matter• Our gourd (A02) is focusing on“Hadron” to reveal and understandthe hierarchical structure of matter• Two experimental projects (originally)
have been proceeded by the A02

2

The hierarchical structure of matter• Our gourd (A02) is focusing on“Hadron” to reveal and understandthe hierarchical structure of matter• Two experimental projects (originally)
have been proceeded by the A02• Hadron spectroscopy- with hadron beam at J-PARC- with photon beam at SPring-8

J-PARCSPring-82

Contents• Introduction• Baryon, meson, and exotic hadron• relation between threshold and cluster• Selected topics• Baryon spectroscopy• meson-baryon interaction• Kaonic-nucleus cluster• SummaryHadron• Particles that interact by the strong interaction are called "Hadron".
• Hadron is known to be a composite particles of quarks.
• Hadrons are categorized as mainly two classes.
• Baryon: Family of proton/neutron. Bound state of three quarks• Meson: quark - antiquark bound state.

BaryonThree fermion system

Meson

fermion-anti-fermion system

Unfortunately, a single quark can not be separated from a hadronConﬁnement of quarks inside hadron

Exotic hadron• Baryons and mesons are not the only conﬁgurations allowed by thetheory of strong interaction, QCD.
• Quark has “color charge” (RBG)→ Color of hadron must be “color neutral (white)”.

• Following conﬁguration can be allowed other than qqq and q̄q conﬁg.
(tetra-quark)• q̄qq̄q• qqqq̄q （penta-quak baryon）• qqqqqq (di-baryon, six quarks）
Exotic hadron

Hundreds of mesons/baryons have been observed
what physics can we extract from this?

How is a hadron formed?

Normal hadrons
BaryonMeson

exotic hadrons

Pentatetra-

quasi-particle: color object• What is the eﬀective DoF insidehadron?

• “colored object”• constituent quark• di-quark?
• a mixture of exotic hadron w/
a hadron-hadron molecule• a hadron-hadron molecule)(

Meson-Baryon
Baryon-Baryon+
Tetrameson-meson

Mixed stateHadron
22
Q ≪ ΛQCD
Q ≫0pQCD
bare
quark

clothed quarkpairclothedquark

const.
quark

di-quarkquasiparticle

colored object

mesonbaryon

colorneutral

How can we learn eﬀective DoF in the hadron• Hadron spectroscopy will have the power to reveal eﬀective DoF• quark dynamics can be extracted through excited states of hadrons• di-quark correlation

In the case of charmed baryon,a ”di-quark” correlation will emerge, eﬀectively
αsVCMI ∼(λi ⋅ λj)( σi ⃗ ⋅ σj )⃗mimjStrong!

weakNormal baryon

baryon w/
one heavy quark• gluon excitation• threshold eﬀect• hadron-hadron

relation between the excited state

8and particle threshold will have a key

to understand eﬀective DoF in hadron

The way to reveal
eﬀective Degree of freedom in hadron

9Charmed baryon spectroscopy• The spectroscopy of charmed baryon (Baryon with one charm quark)has been proposed at J-PARC, J-PARC E50 to shed the light on diquark
correlation in baryon resonance.

• The detector is under construction

E50 spectrometercollaboration work with LEPS2 and E16
AMANEQ

AMANEQ

CITIROC / PETIROC2A board

MPPC amplifier

11E50 spectrometercollaboration work with LEPS2 and E16

Detail will be discussedin Prof. Noumi’s talk
CITIROC / PETIROC2A board

MPPC amplifier

11AMANEQ

AMANEQ

Meson-Baryon interaction

12Kaonic-Nuclear cluster• Kaon-Nucleon/kaon-Nucleons system• The feature of the system is something like,“Boson-Fermion” / “Boson-Fermion-Fermion” system,
sticking with strong interaction.
• A couple of candidates have been investigated in the framework of “A02.”• Λ(1405)• K̄NN• K̄NNNN→ K̄N bound state?

→ bound state of K̄ and two nucleons?

N→ bound state of K̄ and three nucleons?

K̄

K̄N

NK̄

K̄NNNNK̄

K̄NNNNStudy of the Kaonic-Nuclear cluster at J-PARC• A Series of experiments have been performed utilizing high-intensity
K beams available at the J-PARC K1.8BR beamline.
−

J-PARC E31 : Λ(1405)
J-PARC E15 : K̄NN
J-PARC T77 : K̄NNN?

Study of the Kaonic-Nuclear cluster at J-PARC• A Series of experiments have been performed utilizing high-intensity
K beams available at the J-PARC K1.8BR beamline.
−

covered by Prof. Noumiʼs talk
J-PARC E31 : Λ(1405)
J-PARC E15 : K̄NN
J-PARC T77 : K̄NNN?

Study of the Kaonic-Nuclear cluster at J-PARC• A Series of experiments have been performed utilizing high-intensity
K beams available at the J-PARC K1.8BR beamline.
−

covered by Prof. Noumiʼs talk
J-PARC E31 : Λ(1405)
J-PARC E15 : K̄NN
J-PARC T77 : K̄NNN?
discussed in this talkK̄ meson + two nucleons : K̄NN
He(K,Λp)
K̄NN
Reactionfor•3−Phys.Lett.B789(2019)620
Phys.Rev.C102(2020)044002

Clear peak structure below K̄NN thresholdK̄ meson + three nucleons : K̄NNN
He(K,Λd)K̄NNN
Reactionfor•
3−K̄NNK̄ meson + three nucleons : K̄NNNHe(K,Λd)
K̄NNN
Reaction
for
•
3−

K̄NN

K̄ meson + three nucleons : K̄NNN
He(K,Λd)K̄NNN
Reaction
for
•
−K̄NN

K̄NNN?
preliminary

4540

Counts / 30 MeV/c2

30.3 < q < 0.6 GeV/c

3530
2520
15
10503

3.2

3.4mΛd (GeV/c2)

3.6

3.8

K̄ meson + three nucleons : K̄NNN
He(K,Λd)K̄NNN
Reaction
for
•
3−

K̄NN

K̄NNN?
preliminary

45

Counts / 30 MeV/c2

40

0.3 < q < 0.6 GeV/c3530
25201510503

3.2

3.4mΛd (GeV/c2)

3.63.8Similarly, clear peak structure showed up below K̄NNN thresholdKaonic nuclear cluster• Clearly, we observed K̄NN cluster, i.e Meson +Two fermions system
PC• However, we can not determine the quantum numbers, c.f. J etc.
• We found a hit of the existence of K̄NNN cluster.
• However, we need more statistics to extract the mass and decay widthof the observed state.

• Therefore, we started a new project to answer the undetermined
questions above!

Future prospects for the research of Kaonic nuclei• Constructing new large acceptance detector complex

Future prospects for the research of Kaonic nuclei

Study of the Kaonic-Nuclear cluster at SPring-8• The project to study Kaonic-nucleus via photo reaction is in progress at
SPring8-LEPS2 experimentsics at LEPS2

next-term LEPSSPring-8 Masaru Yosoi
RCNP, Osaka Univ.
(Super Photon ring - 8GeV)
decided to continue LEPS and@proposal
Hyogo,
Japanbeen approved.
sion
has recentlyrometer

LEPS with the polarized target

* Charged particles tracking:Acceptance : 7 – 110 deg
Side: Time Projection Chamber (TPC)
Forward : Drift Chamber (DC x 4)
* γ-rays
Acceptance : 40 – 110 deg
Barrel-g 1st – 3rd layer (Full : 4 layers)* Particle Identification (p/K/p)
Side: Barrel Resistive Plate Chamber (RPC)
Middle : Aerogel Cherenkov Counter
Forward: Forward RPC

Detector construction has been completed

Detector performance
Particle identiﬁcation

Reconstructed events

we started taking physics data since October 2021
LH2 : ~1.5
LD2 : ~4.0

1012 photon on target.

1012 photon on target.

Study of the Kaonic-Nuclear cluster at SPring-8• Photo production of Λ(1405) :γ + p → Λ(1405) + K*+

reaction

Uniqueness of the measurement at
the LEPS2 experiment “photon polarization”

Transition form factor (p → Λ(1405)) can be measured
which contains size information of Λ(1405)→ we may conclude whether Λ(1405) is a compact object or not.

Study of the Kaonic-Nuclear cluster at SPring-8• Photo production of Λ(1405) :γ + p → Λ(1405) + K*+

reaction

Uniqueness of the measurement at
the LEPS2 experiment “photon polarization”

Transition form factor (p → Λ(1405)) can be measured
which contains size information of Λ(1405)→ we may conclude whether Λ(1405) is a compact object or not.

Study of the Kaonic-Nuclear cluster at SPring-8• Study of K̄NN via d(γ, Λp) rection

New information of K̄NN will be delivered soon

detecting ﬁnal state particles (Λp)
by main tracking detector, TPC

from the LEPS2 which has a diﬀerent production
mechanism other than K − induced reaction

The hierarchical structure of matter

24

The hierarchical structure of matter
Photo production Λ(1405), K̄NN,
Pentaquark baryon at SPring-8

24

The hierarchical structure of matter
Photo production Λ(1405), K̄NN,Pentaquark baryon at SPring-8

Λ(1405), K̄NN, K̄NNN

24

The hierarchical structure of matter
Photo production Λ(1405), K̄NN,
Pentaquark baryon at SPring-8

Λ(1405), K̄NN, K̄NNN

J-PARC E31/E15/E73/E80
24

The hierarchical structure of matter
Photo production Λ(1405), K̄NN,
Pentaquark baryon at SPring-8

Λ(1405), K̄NN, K̄NNN

Baryon spectroscopy
at J-PARC

J-PARC E31/E15/E73/E80
24Summary• Reveal the relation between quark and hadron, hadron and nucleus hierarchy.
what is the eﬀective DoFs to describe hadron• The preparation of the experiment is in progress: J-PARC E50 experiment :(Detail will be discussed by Prof. Noumi)• Physics data taking is started.

: SPring-8/LEPS2-solenoid :→ new results will be delivered soon.

• New data analysis with existing data is ongoing• Λ(1405) : the J-PARC E31 experiment• K̄NN• K̄NNN: the J-PARC E15 experiment: the J-PARC E80 experimentSummary•What are we learning so far?

• We already obtained hints about the hadron (meson) will be aconstituent of the matter (other than baryon) (Λ(1405), K̄NN, K̄NNN (?), etc.).

• all states are seen very close to the threshold energy→ need an investigation of whether this “threshold eﬀect” isthe same eﬀect that is seen in other hierarchies → Universality?

• Diquark will play a major role in a hadron, hits have already been seen in
high-energy experiments/ theoretical works.

→ charmed baryon spectroscopy at J-PARC will give a new insight
into the topics of the hierarchical structure of matterSummary•What are we learning so far?

• We already obtained hints about the hadron (meson) will be aconstituent of the matter (other than baryon) (Λ(1405), K̄NN, K̄NNN (?), etc.).

• all states are seen very close to the threshold energy→ need an investigation of whether this “threshold eﬀect” isthe same eﬀect that is seen in other hierarchies → Universality?

• Diquark will play a major role in a hadron, hits have already been seen in
high-energy experiments/ theoretical works.

→ charmed baryon spectroscopy at J-PARC will give a new insight
into the topics of the hierarchical structure of matter

we will show some new results fromJ-PARC E50 and SPring-8 LEPS2 near future