加速器を用いたハドロン物理実験

加速器を用いたハドロン物理実験K. Ozawa (KEK)

内容• 原子核の性質

– ストレンジネスで探る原子核内部– ハドロンーハドロン相互作用– 原子核媒質とメソン

• 核子（バリオン）の中身– ストレンジバリオン– Di-quark 相関

2013/10/30 Hadron Experiment, K. Ozawa 2

J-PARC (Japan Proton Accelerator Research Complex)

Tokai, Japan

50 (30) GeV Synchrotron (15 mA)

400 MeV Linac (350m)

3 GeV Synchrotron (333 mA)

Material and Biological Science Facility

World-highest beam intensity : ~1 MW x10 of BNL-AGS, x100 of KEK-PS

Neutrino Facility

Hadron Hall60m x 56m

2013/10/30 3Hadron Experiment, K. Ozawa

Nuclear & Hadron Physics at J-PARC

L,X N

ZL, S Hypernuclei

LL, X Hypernuclei

Stra

ngen

ess

0

Hypernuclei

-1

-2

Proton Beam

K1.8

KL

K1.1BR

High p (not yet)SKS

K1.8BRK1.1

d

uu

d

s

Pentaquark +LLHe6

Free quarks Boundquarks

Why are bound quarks haevier ？

Quark

Mass without Mass PuzzleKaonic nucleusKaonic atom

Ｘ ray

Ｋ−

Implantation ofKaon and the

nuclear shrinkage

K meson


KL

K1.1BR

North side

South sideH

igh Mom

entum

SKS

K1.8BR


SKS Spectrometer

Q10 Q11

Q12Q13

D4


核構造とストレンジネス


原子核構造

偶－偶核の第一励起準位エネルギー　（閉殻構造、魔法数の存在）

1 体ポテンシャルによる励起準位

調和振動子

井戸型

ウッド・サクソン

励起準位（調和振動子、井戸型）2013/10/30 Hadron Experiment, K. Ozawa 8

ストレンジネス

1 体ポテンシャルによる励起準位

PRC 64 (2001) 044302

-> UL = - 28 MeV (c.f. UN = -50 MeV)

ストレンジネスは、 Pauli Blocking を受けないので、原子核の中に置ける。実際に、殻構造があることを実証


束縛エネルギーは、違っていた。

ストレンジネス束縛エネルギーPRC 64 (2001) 044302

-> UL = - 28 MeV (c.f. UN = -50 MeV)

束縛エネルギーの違いがもたらす物理

Experimental input to models

Schaffner-Bielich, NP A804 (2008).

Baryon fraction in neutron star

One example…

More experimental information on LN, XN, LL, SN interactions are awaited.


Precise measurements of LN (E13)• g spectroscopy for light hyper nuclear using (K-, p-)

reaction at pK=1.5 (or 1.1) GeV/c.• Physics: LN interaction

– Charge symmetry breaking in LN interaction• 4

LHe : Large CSB is suggested

– sd-shell hypernuclei for A-dependence of LN interaction• 19

LF : The first sd-shell hypernuclei

– Confirm LN spin-dependent forces and study LN-SN coupling force

• 10LB and 11

LB

• Physics: g-factor of L in nucleus– Spin-flip B(M1) measurement for gL in a nucleus

• 7LLi : Least ambiguities and most reliable.

• Hyper Ball-J is almost ready and we will take the first experimental data soon.


Beam

LL interaction (E07)• At KEK-PS E373, there are ~ 700 X stops and one NAGARA

event is observed.– ΔBLL = 1.01±0.20 MeV for L6

LHe

• At J-PARC, S=-2 nuclear chart is studied by ~102 LLZ via 104 X --stopping events.– DBLL of several nuclides will provide definitive information on LL

interaction and structure of S=-2 nuclei.


Experimental Method(Nuclear Emulsion)

The experiment is under preparations and it will be performed in the end of this year or early next year.

XN interaction (E05)

• Discovery of X-hyper nucleus using 12C(K-,K+) reaction– 12

XBe

• Missing mass spectroscopy – High resolution

• Originally, 3 MeV(FWHM)• 1.5 MeV will be achieved using a

new spectrometer

• Experiment will start in 2015 and we can expect more than 200 events of X-hyper nucleus– Precise spectroscopy


Expected Spectrum (Will be improved using a new spectrometer)

ハドロンーハドロン相互作用2013/10/30 Hadron Experiment, K. Ozawa 14

バリオンーバリオン相互作用

Example ：　陽子・中性子・重陽子の性質

図は、八木浩輔・原子核物理学

中性子・陽子散乱の角分布


ストレンジネスを含む相互作用の違いの起源はどこに？中性子・陽子の相互作用の研究は、散乱実験これはストレンジネスでも可能２体束縛状態（重陽子）の研究ストレンジネスセクターに存在しない。

SN Scattering (E40)• Differential cross section of S-p and S+p scattering with 100 times larger

statistics • Motivation: See “quark-Pauli effect”


meson exch

quark + meson exch

Evaluation of quark Pauli effect and understanding the origin of the hard core of the nuclear force

S+p (quark Pauli)

Hyperon production 1.3 GeV/c p+- p -> K+ S+- reaction S+- track not directly measured Measure proton momentum vector -> kinematically complete

New experimental techniques with MPPC and Fiber Tracker will be used

メソン－バリオン相互作用（ KN, E15 ）

17

Physics motivation

Experimental setup

Experimental scheme

Experiment is on-going2013/2/11 J-PARC Future 2013, K. Ozawa

Results of an engineering runXY plane YZ plane

Liquid 4He insideTarget-image together with material around

has been reconstructed by the CDSCharged particles from the target have been successfully identified by the CDS

18

pp- invariant-mass spectra reconstructed

by the CDSL

~10,000 Ls have been accumulated2013/10/30 Hadron Experiment, K. Ozawa

CDS and Liquid Helium target system successfully worked

Ready to explore kaonic-nuclei @ K1.8BR

Data Taking in this May!

19

E27: Search for “K-pp” bound state in the d(p+,K+)X reaction

• “K-pp” is produced through L* doorway in the d(p+,K+) reaction

• Semi-exclusive measurement by Range Counter Array (RCA) in order to suppress quasi-free B.G.– K-pp ® L p1, L ® p2 p-

– K-pp ® S0 p1, S0 ® (Lg) ® p2 p- g– p+d ® L* K+ p1s, L* ® S p, S+ ® p2 p0

np K-ppd

Λ*π+ K+

RCA

K+

p

2013/10/30 Hadron Experiment, K. Ozawa Missing mass d(π+,K+) [GeV/c2]

Momproton>350MeV/c

coun

ts (/

3M b

eam

・10da

ys )

Expected point by FINUDA, DISTOData already collected and

results will be reported soon.

原子核媒質とメソン2013/10/30 Hadron Experiment, K. Ozawa 20

Mas

s [G

eV]

媒質からの励起状態としてのハドロン


NG ボソンとしての擬スカラー中間子（ Jp=0- ）

構成子クォークの質量を獲得

• カイラル対称性の自発的破れに伴う質量の獲得• π 中間子が異常に軽い（ Mp ~

130 MeV/c2 ）ことは、対称性の自発的破れに伴う南部ゴールドストンボソンと理解• 実際にカイラル対称性は破れている。

– カイラルパートナーに質量差があることが知られている媒質中での中間子の測定原子核媒質の性質の測定原子核 - 中間子相互作用の測定

p 束縛状態


Large overlap of wave function

Sensitive to p-nucleus strong interaction potential

Measure binding energy can be converted to this b1 information

Exp. Results


K. Suzuki et al., Phys. Rev. Let., 92(2004) 072302

p bound state is observed in Sn(d, 3He) pion transfer reaction at GSI.Reduction of the chiral order parameter, f*p(r)2/fp2=0.64 at the normalnuclear density (r = r0 ) is indicated.

Experiment is continued at RIKEN and positive results are already obtained.

Other Pseudo Scalar Meson: h

2013/10/30 Hadron Experiment, K. Ozawa

LOI by K. Itahashi et. al Calc. by H. Nagahiro, D. Jido, S. Hirenzaki et. al

Forward neutron is detected.missing mass distribution is measured.

In addition, measurements of invariant mass of N* decay

Simulation

24

Other Pseudo Scalar Meson: h’ @ GSI


Reaction is similar with pionic atom experiment.

Theoretical calculation by H. Nagahiro

反クォーク・クォーク凝縮量• 反クォーク・クォーク凝縮量と関係した測定量

– ベクトル中間子や軸性ベクトル中間子の質量分布– Weinberg type sum rule

– たとえば、自由空間中で、 t粒子の崩壊からの分布の測定がある。（ ALEPH, Phys. Rep. 421(2005) 191 ）– 自由空間以外での測定は、実験的に難しい


Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694

Example: sum rulee.g. Weinberg type QCD sum rule

Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694


ALEPH, Phys. Rep. 421(2005) 191

さらに、反クォーク・クォーク凝縮量• QCD sum rule をベクトル中間子の質量分布に適用し、凝縮量と関係づけられると示唆• 実験的には、

– ベクトル中間子質量分布の測定は可能– 原子核中や高温ハドロン物質中での測定も可能

• 内包する凝縮量の違いを反映する• 質量獲得モデルや“ QCD 媒質”状態予想の検証

– 自由空間以外でのベクトル中間子の質量分布測定が基礎情報として重要2013/10/30 Hadron Experiment, K. Ozawa 28

Hatsuda and Lee, Phys. Rev. C46 (1992) R34

KEK-PS E325 実験へ• 原子核密度に対する面白い予想の存在

– 凝縮量と質量分布の関係と以下の仮定を基に予想• 質量分布の形

– 凝縮量の変化の効果をポール位置の変化に集約• 核子内の凝縮量の評価• 凝縮量は、密度に線形に変化

– 原子核中で、 18 ％（ ρ, ω ）と 1.8% （ φ ）の質量変化を予測• 実験的に検証可能

– 原子核中での崩壊により質量分布を測定– 終状態相互作用を避けるために電子対崩壊を選択– バックグランドや ρ-ω 干渉に関する不定性を避けるため、 φ 中間子に対して測定

• φ 中間子の幅は狭い（ 4.3 MeV/c2 ）。質量変化が測定しやすい。• あらわなハドロン相互作用の効果は小さい。

– e.g. Binding energy of fN is 1.8 MeV (Phys. Rev. C 63(2001) 022201R)


Hatsuda and Lee, Phys. Rev. C46 (1992) R34

Hatsuda and Kunihiro, Nucl. Phys. B387 (1992) 715

KEK-PS E325 実験の概要


12 GeV proton induced. p+A ® f + X

Electrons from f decays are detected.

TargetCarbon, Cupper0.5% rad length

KEK E325

Clear measurements of f meson at KEK-PS.

2013/10/30 31

R. Muto et al., PRL 98(2007) 042581

Indication of QCD-originated mass modification!

Cu

bg<1.25 (Slow)

e+e- invariant mass

Decays inside nucleusDecays outside nucleus

fmeson has mass modification

Modification is shown as an Excess

fmeson has NO mass modification

Blue line shows expected line shape including all experimental effectswo mass modification

The only one measurement on medium modification of f meson.

Hadron Experiment, K. Ozawa

322013/10/30

Target/Momentum dep.bg<1.25 (Slow) 1.25<bg<1.75

Only one momentum bin shows a mass modification under the current statistics.

To see clear mass modification and establish QCD-originated effects, significantly larger statistics are required.

e+e- invariant mass

Two nuclear targets:Carbon & CopperInside-decay increases in large nucleus

Momentum binSlowly moving f mesons have larger chance to decay inside nucleus

Same as previous slide

Excess


KEK-PS E325 で得られたもの• 原子核中での φ 中間子の質量分布変化を示唆するデータ• 得られた分布を φ 中間子の質量ピーク位置の変化として解釈すると、 3% の変化• 初田 -Lee 予想と Consistent だが、偶然かもしれない。

– 核子内の <ss> 凝縮量は、非常に小さいという Lattice の計算（ H. Ohki et. al, Phys. Rev. D 78(2008) 054502 ）– 密度に対する凝縮量の線形近似– 中間子生成過程、中間子崩壊点の密度の不定性


次に、何を目指すか？• KEK-PS E325 の結果の Confirm

– 世界的にも、他に φ 中間子の結果は得られていない。• 原子核密度における質量分布の確立

– 凝縮量との関係に対する議論に耐えられるデータ– 生成過程、密度分布などの不定性の小さいデータ

• 単なる質量分布を超えた測定– 媒質中で質量に対応するものは、エネルギーと運動量の分散関係


J-PARC での実験の目標

2013/10/30 35

Pb

Proton

A clear shifted peak needs to be identified to establish QCD-originated effects

Momentum Dependence

E325 results Extrapolate

Hadron Experiment, K. Ozawa凝縮量の評価を可能にする高統計測定

さらに、


Pb

fModified f

[GeV/c2]

f from Proton

Invariant mass in medium

ff

fff

ff

fp dep.

Dispersion relation

Experimental set up


Cope with 1010 per spill beam intensity (x10)Extended acceptance (90 in vertical) (x5)Increase cross section (x2)

Construct a new beam line and new spectrometer

Deliver 1010 per spill proton beam Primary proton (30GeV) beam

New high momentum beam line

Detector components

2013/10/30 38

100x100 200x200 300x300

Position resolution of 100mm is achieved

GEM Tracker

HBD (Hadron-Blind Cherenkov detector )

Both detectors based on Gas Electron Multiplier (GEM) technology Recently, we succeed making a proto-type which meets our experimental

requirements. Now, we are preparing a mass production of detectors.

Key Technology:CsI evaporated GEM as a photo cathodeQ.E. of 40% is achieved


E29: f bound state?

2013/10/30 Hadron Experiment, K. Ozawa

ssuud

K+

Λ

Φ

p ud

sus

fp -> K+L

pp -> ff

39

Mass shift of f in nucleus can produce a bound state?

Production

Detection

J. Yamagata-Sekihara, D. Cabrera, M. J. Vicednte-Vacas, S. Hirenzaki; 'Formation of Φ mesic nuclei'; Progress of Theoretical Physics 124, 147-162 (2010).

E26: Omega in nucleus

2013/10/30 40

g g

gp

w p0

n

p-A ® w + n+X

gg

p0g

2ppm gpw +

Measurements of w meson in nucleusProduction of w is also measuredFocus on low momentum w meson

ConstructNeutron counterGamma Detector

Beam Momentum is 2.0 GeV/cIt can be done at K1.8 and also at new high momentum beam line


H. Nagahiro et al, Calculation for 12C(p-, n)11Bw

Missing Mass(Bound state?)

Invariant Mass

ハドロン内部構造2013/10/30 Hadron Experiment, K. Ozawa 41

アイソスピン対称性・クォークモデル陽子：　｜ 1/2, ＋ 1/2 ＞ , S = 0中性子：｜ 1/2, － 1/2 ＞ , S = 0π 中間子：　 I=1 の 3 重項 , S = 0

p+p, p-p 反応の断面積Particle Data Book, Phys. Let. B667(2008), 1

Baryon

但、クォークの数を３つとする原理的理由はない。2013/10/30 Hadron Experiment, K. Ozawa 42

E19:Penta quark - results 2010 data

No peak of + was observed.

U.L. (90%CL) 0.26mb/sr (2 － 14°) in 1.51 － 1.55GeV/c2

U.L.(90%CL) of G

0.72 MeV (1/2+) 3.1 MeV (1/2-)

Search for the Θ+ via the p+π-→K-+X 　 Reaction at 1.97GeV/c

PRL 109 (2012) 132002

PRL publishedUpdated data with higher beam momentum exists.See Dr. Naruki’s talk.


H dibaryon search (E42)• The observation of several double-L

hypernuclear events in nuclear emulsion suggests that the H-dibaryon is very closely bound or unbound relative to 2mL .

• Some experimental results show an enhancement just above 2mL mass (~ 2250 MeV/c2).

– J.K. Ahn et al., PLB 444 (1998) 267– C.J. Yoon et al., PRC 75 (2007) 022201(R)

• Weakly-bound : H -> Lpp• Virtual state : LL threshold effect

• Precise measurements of LL and Lpp productions in 12C(K-, K+) reactions are proposed. – Forward K spectrometer and a time projection

chamber around the target is used.


Expected spectrum for a virtual state

Experimental setups

クォーク・反クォーク　ポテンシャル

Harmonic Oscillator 型Potential の励起状態

Coulomb Potential (Positronium) との比較

Charmonium 　（ c-c ）の励起状態Martin and Shaw, Particle Physics

q-q ポテンシャル実線： -a/r + br 、破線 : a ・ln(br)2013/10/30 Hadron Experiment, K. Ozawa 45

Diquarks

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

8

9

10

NDeltaLambdaSigmaXi

0 1 2 3 4 5 6 70

1

2

3

4

5

6

7

8

9

10

rho/aomega/fphi/fK*

Baryons Mesons

LL

M2 (

GeV2 ) M2 1.1∝ L M2 1.1∝ L

Baryons as well as Mesons seem to be well described by a Rotating String Configuration with a universal string tension.

Emergent DiquarksBaryons as well as Mesons seem to be well described by a

Rotating String Configuration with a universal string tension.

“diquark”in low-lying modesqq

q

Heavy quark baryon• When single quark picture is still a

good picture, excited states are degenerated.

• If Cqq (q=u,d) system is considered as C and di-quark correlations, orbital motion of l is lowered due to the collectivity of the di-quark motion.

• Spin correlations between light quarks give additional level separations.

2013/10/30 48

l: orbital motionr: di-quark correlation

Hadron Experiment, K. OzawaMeasurements of all levels are important

Level pattern tell us:Mass of di-quark Strength of di-quark

correlationSpin dependent correlation

between light quarks

Missing mass Spectroscopy

• Large Acceptance, Multi-Particle– K, p from D0 decays– Soft p from D*- decays– (Decay products from Yc*)

• High Resolution• High Rate

– SFT/SSD op. >10M/spill at K1.8

2.3 Tm Dipole

H2 TGT

Beam p-

PID

p-

K+DC

TOF

PID

p-

DCHigh rate Trackers(Fiber, SSD)

LAMPS

Use forward D mesons productionNo Bias measurements up to 3GeV/c2 of Charmed Baryon mass


Signal: 1 nb/Yc* :~1000 eventsBG: 1.8 mb (JAM)

Lc 1/2+

Sc(2455) 1/2+

Sc(2520) 3/2+

Sc(2800) ??

Lc(2595) 1/2-

Lc(2625) 3/2-

Lc(2880) 5/2+

Lc(2940) ??

DN

pLc

(GeV/c2)

D*N

2.3

2.4

2.7

2.9

2.6 pSc

2.8

Expected Spectrum in the (p,D*-) reaction

Lc

S c(2

455)

S c(2

520) Lc(2

625)

Lc(2

765)

Lc(2

880)

Lc +

0.8

GeV

Missing Mass (GeV/c2)

pSc DN D*N

Lc(2

595)

S c(2

800) Lc(2

940)

Summary

• Several experiments are being performed and prepared at J-PARC to investigate hadron interactions, nuclear medium effects and internal structure of hadrons.

• Currently, strangeness nuclear physics and Kaon bound system are intensively studied. In near future, meson properties in nucleus and level structure of charmed baryons will be measured.


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加速器を用いた ハドロン物理実験

加速器を用いたハドロン物理実験