Baryons’10@Osaka.Univ 2010/12/10

Shun EnomotoRCNP,Osaka.University

For the J-PARC E31 collaboration

Spectroscopic study of Lambda(1405) via the

(K-,n)reaction on deuteron.

1

• Introduction　 -Λ(1405) -(K-,n) reaction on deuteron.

• J-PARC E31 experiments　 -Experimental method(identify I=0 state in KbarN->πΣ process)

• Preparation status -Development detector

• Summary

Contents

2

Introduction

3

• 3quark?5quark?

• KbarN1406.5MeV/c2[one pole?]

Deeply bound KbarN state.Y.Akaishi & T.Yamazaki, Phys. Rev. C65(2002) 04405.Y.Akaishi & T.Yamazaki, Phys. Lett. B535 (2002) 70

1420MeV/c2[two pole?]Chiral Unitary Model predicted.

T. Hyodo, D. Jido, and A. Hosaka, Phys. Rev. Lett. 97, 192002(2006);T. Hyodo, D. Jido and A. Hosaka, Phys. Rev. D75, 034002(2007).T. Hyodo and A. Weise, Phys. Rev. C77, 035204(2008)

Λ(1405)

4

I=1

I=0

∑(1192),1/2+

∑*(1385),3/2+

Λ(1116),1/2+

Λ(1405),1/2-

Λ(1520),3/2- KN(1432)

-27MeV

A spectroscopic study of Λ(1405) directly coupled to KbarN is desired. KbarN scattering below KbarN threthold.→d(K-,n) reaction

Motivation・ To clarify whether Λ(1405) is KbarN resonant state.

the(K-,n) reaction on Deuteron.

pn

2H

n

∑

π

K-

t

Y*K

5

Non-resonantI=1

Σ*(1385)P-waveI=1 Λ*(1405)?

Y*(mass)

S-waveI=0,1

1420MeV/c2?

1405MeV/c2?

KN :1432MeV

Λ(1405) and BG(NR/∑*)• S-wave,I=0 　→ Λ*(1405)→π0∑0,π-∑+ ,π+∑-

• S-wave,I=1 　 → non-resonant(NR)• P-wave,I=1 →∑*(1385) → π0Λ,π-∑+ ,π+∑-

Purely I=0

J.Yamagata-Sekihara,T.Sekihara,and D.Jido,paper in preparation

Possible ID of I=0 in KbarN->π∑Possible decomposition of I=0 amplitude.

J-PARC E31 experiments

6

J-PARC E31 Collaboration

7

• S. Ajimura1, G. Beer2, H. Bhang3, M.Bragadireanu8,P. Buehler4, L. Busso5,6, M. Cargnelli4, S. Choi3, C. Curceanu8, S. Enomoto1, D. Faso5, H. Fujioka13, Y. Fujiwara12, T. Fukuda11, C. Guaraldo8, T. Hashimoto12,R. Hayano12, T. Hiraiwa 13, M. Iio9,K. Inoue1, N. Ishibashi17, T. Ishikawa12, S. Ishimoto14, T. Ishiwatari4, K. Itahashi9, M. Iwai14, M. Iwasaki9,10,S. Kawasaki1, P. Kienle15, H. Kou10,J. Marton4, Y. Matsuda12, Y. Mizoi 10, O. Morra5, T. Nagae13, H. Noumi 1, H. Ohnishi9, S. Okada8, H. Outa9,Y. Sada13, A. Sakaguchi17, F. Sakuma9, M. Sato12, M. Sekimoto14,H. Shi12, D. Sirghi8, F. Sirghi8, S. Suzuki14, T. Suzuki12, H. Tatsuno12, M. Tokuda10, D. Tomono9, A. Toyoda14, K. Tsukada9, E. Widmann4, T. Yamazaki9,12, K. Yoshida17, H. Yim3, B. Wünschek4, J. Zmeskal4

• 1. Research Center for Nuclear Physics, Osaka University, Japan • 2. University of Victoria, Canada, 3. Seoul National University, South Korea• 4. Stefan Meyer Institut fur subatomare Physik, Austria, • 5. INFN Sezione di Torino, Italy , 6.Universita’ di Torino, Italy• 8. Laboratori Nazionali di Frascati dell’INFN, Italy• 9. RIKEN, Japan, 10. Tokyo Institute of Technology, Japan • 11. Osaka Electro-Communication University, Japan, 12. University of Tokyo, Japan • 13. Kyoto University, Japan, 14. High Energy Accelerator Research Organization

(KEK), Japan • 15. Technische Universitat Munchen, Germany, 16. INAF-IFSI, Sezione di Torino, Italy• 17. Osaka University, Japan

• Spectroscopic study of Hyperon Resonances below KbarN threthold via the (K －,n) reaction on Deuteron.

15m

Neutron counter(TOF)ΔT~150ps

Decay Particle

Detector(CDS)

K － 1.0GeV/c

n~1.3GeV/c

Λ(1405)

2)( ndKX PPPMM

Target(D)

・ To measure Λ* mass spectra by Missing Mass .

・ To Identify Λ* decay mode by CDS

3He(K-,n)”Kpp” reactionJ-PARC E15@J-PARC K1.8BR

Σ-π+,Σ+π-→I=0 　 Λ* I=1 NR I=1 Σ*Σ0π0 →I=0 Λ*Λπ0 →NR or Σ*

J-PARC E31 Experiments

8

・ σMM~9MeV/c2 at PK- = 1.0GeV/c

15m

K-

beam beam spectrometer

J-PARC K1.8BR

9

neutron counter

Rearra

nge

Decay particle detector(CDS)

Liq.D target

2010/10/25

case1:π+∑- and π-∑+

Λ(1405)→ 　 ∑ +π-→ (nπ+) π-

　　　 　　　 ∑ -π+→ (nπ-)π+ 　

10

Identification of Λ* decay mode.

case2: π0∑0 and Λπ0(NR/∑*) Λ(1405) 　　 →∑ 0π0→Λγπ0→(pπ-)γ π0

　　 NR/Σ(1385) →Λπ0 →pπ-π0 　　　　　　　

target

CDC(Drift chamber)

ZVC

Solenoid magnet

CDH

π-π+

n(~1.3GeV/c)

Λ(1405)→ 　∑ +π-→ (nπ+ )π- or ∑-π+→ (nπ-) π+

∑+

n

K-=1.0GeV/c

Λ(1405)

0.1~0.2GeV/c0.1~0.3GeV/c

0.5T

The J-PARC E15 setup is quite suitable to detect π.

Detection of the Λ* ->∑-π+ and ∑+π-modes

11

Identification of the decay modes:Λ* ->∑-

π+ or ∑+π-

1340 1360 1380 1400 1420 1440 14600

0.1

0.2

0.3

0.4

0.5

0.6

S-pi+cut

S+pi-cut

Hyperon mass (MeV/c2)

effici

ency

1340 1360 1380 1400 1420 1440 14600

0.0020.0040.0060.0080.01

0.0120.0140.016

X(MeV/c2)

mis

sID

(rat

io)

MissingMass2(MeV/c2)2

22 )(

PPPPMM ndK

(∑+π-) MM(mass)

(Σ-π+): MM(Σ-

mass)

Γ(Λ*→∑+π-)/Γ(Λ*→∑-π+) ～ 1

missID(Σ+π-)=(∑-π+[①])/(Σ+π-[②])

×103

②

Σ+π-

Σ-π+

Σ+π- Σ-π+

12

①①

KbarN

Λ*→∑0π0 ,(∑*→Λπ0)

target

CDC(Drift chamber)

ZVC

Solenoid magnet

CDHπ-:~200MeV/c

P:~500MeV/c

Λ(1405)→∑0 π0→Λγπ0→ (p π-)γ π0

NR/∑(1385)→Λπ0→(pπ-)π0

K-=1.0Gev/cπ0

∑0n(~1.3GeV/c)

Backward Protondetector(BPD) & chamber(BPC)

BPD measures to momentum of proton by TOF methods. 13

ID & Efficiency for Λ*->π0Σ0

222 )()( PPPPPPMM pndKYY

P:fourth momentum

MM2(MeV/c2)2

Λ*->π0Σ0

([π0+γ]mass)

Σ*->Λπ0(π0mass)

Γ(Λ*)/Γ(Σ*) ～ 1

Proton DetectorResolution(σ)

×103

Λ*->∑0π0

Λπ0(contamination)=(Λπ [②])/(Λπ)

Λ(1405)→∑0 π0→Λγπ0→(p π-)γ π0

NR/∑(1385)→Λπ0→pπ-π0

① ②

Σ*->Λπ0 contamination

14

effici

ency

Hyperon X mass[MeV/c2]

Preparation status

15

Backward Proton Detector(BPD)

Prototype(BPD):5mm2×400mm Scintillator with MPPC-50μm

MPPC-50μmσ=246.4ps

(T0-PD)

Meantime[ns]

Beam test:Time Resolution(BPD-T0) σ~250ps

• TOF for proton->Scintillation Hodoscopes

with MPPC.

16

117m

m

168m

m

ASD base

Backward Proton Chamber(BPC)

Vertex Detector for Λ->pπ-

-> determine the reaction point(z vertex) for better Pn measurement in Λ*-> π0Σ0

• Wire gap 3.6mm(xx’yy’xx’yy’:8layers)• Active area φ111.6mm(readout:15ch(1layer))• Outside diameter φ=168mm(z-TPC inside

diameter φ=170mm) 17

• We propose to study Λ(1405) hyperon resonance via the d(K-,n) reaction.

→To investigate Λ(1405) in the coupled channel

KbarN->πΣ system.

• We found that the J-PARC E15 setup has sufficient detection efficiency to identify Λ*->π+Σ- and Λ*->π-Σ+ clearly.

• We introduce BPD & BPC to identify Λ*->π0Σ0

clearly .

Summary

18Thank you

Back up

19

~2011:Summer;BPC & BPC will be ready

2011:Autumn~;Engineering run start?

201? ;E31 experiment start?

Future plan

20

Intensity 30GeV-27kW(6s)Secondary beam K-:1.0GeV.cBeam intensity(Ib) 2.0*10^5per pulse 6s spill intervalCross section(dσ/dΩ) 220μb/sr

97128

Λ(1405)→π+∑-→π+π-nΛ(1405)→π-∑+→π-π+nΛ(1405)→π0∑0→π0π-p

Solid angle(ΔΩ) 0.020srDecay mode efficiency(εM)

0.320.160.015

Λ(1405)→π+∑-→π+π-nΛ(1405)→π-∑+→π-π+nΛ(1405)→π0∑0→π0π-p

Target 4.1*10^23 Liquid deuteron(8cm)Yield(120shift) ~19200

~4800~350

Λ(1405)→π+π-nΛ(1405)→π-π+nΛ(1405)→π0π-p

AMRtb ddnIY

R:reconstruction(0.24)A:analysis(0.9)

Yield estimation (E31 experiment)

10deg4deg

0deg

D(K-,n)X(1400)

fmMeVcfmrprL

cMeVPcMeVP CMNKLabNK

200~,1~,1

/160~,/250~ )()(

S-wave KbarN scattering is dominant at θn =0 degree.

P_KN

• Simple the reaction mechanism.->d(K-,n)π+Σ- at PK-=800MeV/c

K- D nKN

22

1340 1360 1380 1400 1420 1440 14600

0.1

0.2

0.3

0.4

0.5

0.6 eff for Sig-pi+eff. for Sig+pi-

Y* Mass (MeV/c2)

effici

ency

/Mis

-ID r

atio

23Contamination(Mis-identification) ~a few%

• Clebsch-Gordan coeficients

Λ(1405)/Σ(1385)_1

31

32

210,0

210

210,1

61

32

610,2

00

00

• Σ(1385)[I=1] can not decay π0Σ0 .

)1,1(),0,1(),1,1(,,

)1,1(),0,1(),1,1(,,

,,,

0

0

2211,, 2211

mjmjCMJ MJmjmj

24

target

CDC(Drift chamber)

ZVC

Solenoid magnet

CDH

π-π+

n(~1.3GeV/c)

Λ(1405)→ 　∑ +π-→ (nπ+ )π- or ∑-π+→ (nπ-) π+

∑+

n

K-=1.0GeV/c

Λ(1405)

0.1~0.2GeV/c0.1~0.3GeV/c

angle

mom

entu

m

0.5T

Σ+π- Σ-π+π-

The J-PARC E15 setup is quite suitable to detect π.

Detection of the Λ* ->∑-π+ and ∑+π-modes

25

Λ*→∑0π0 ,(∑*→Λπ0)

target

CDC(Drift chamber)

ZVC

Solenoid magnet

CDHπ-:~200MeV/c

P:~500MeV/c

Λ(1405)→∑0 π0→Λγπ0→ (p π-)γ π0

NR/∑(1385)→Λπ0→(pπ-)π0

K-=1.0Gev/cπ0

∑0n(~1.3GeV/c)

proton

angle

mom

entu

m

Σ0π0 Λπ0

Backward Protondetector(BPD) & chamber(BPC)

BPD measure s to momentum of proton TOF methods. 26

• Λ(1405)→π-Σ+→π- (pπ0) [51.57%] or π-(nπ+) [48.31%] 　 π+Σ-→π+(nπ-)[99.84%] π0Σ0→π0Λγ→π0(nπ0)[35.8%] or

π0(pπ-)γ[63.9%]

• Σ(1385)→πΛ[87.0%] →πΣ[11.7%]

Decay mode[Λ(1405)/Σ(1385)]

27

Cylindrical Detector System• A newly developed system for invariant mass

study

28

Expected mass resolution : - ~ 3.0 MeV/c2 for L - ~ 13 MeV/c2 for K-pp( cdc = 200 mm / Field : 0.5 T)

Neutron counter

29

3.2 m

1.5 m

E549 neutron counter

support frame for E15

rearrange

• 20 x 5 x 150 cm3 Plastic Scintillator• Configuration : 16 (wide) x 7 (depth)• Surface area : 3.2m x 1.5m• missing mass resolution for K-pp = 9.2 MeV/c2 (Pn=1.3 GeV/c, TOF=150 ps)

Λ*

J.Yamagata-Sekihara,T.Sekihara,and D.Jido,paper in preparation

D(K-,n)π+∑- 　 (PK=800MeV/c)

30

10deg4deg

0deg

D(K-,n)X(1400)

fmMeVcfmrprL

cMeVPcMeVP CMNKLabNK

200~,1~,1

/160~,/250~ )()(

L=0,s-wave の反応断面積が大きい

KN の運動量

中性子の運動量

31

Motivation

・ To clarify whether Λ(1405) is KbarN resonant state.

KbarN scattering below KbarN threthold.→d(K-,n)Λ* reaction is KbarN direct reacion.

the(K-,n) reaction on Deuteron.

pn

2H

n

∑

π

K-

t

Y*

K

32

Non-resonantI=1

Σ*(1385)P-waveI=0 Λ*(1405)?

Y*(mass)

S-waveI=0,1

1420MeV/c2?1405MeV/

c2?

KN :1432MeV

Possible ID of I=0 in KbarN->πΣ• S-wave,I=0 　→ Λ*(1405)→π0∑0,π∑+ ,π+∑-

• S-wave,I=1 　 → non-resonant(NR)• P-wave,I=1 →∑*(1385) → π0Λ,π-∑+ ,π+∑-

33

the(K-,n) reaction on Deuteron.

Λ*

J.Yamagata-Sekihara,T.Sekihara,and D.Jido,paper in preparation

D(K-,n)π+∑- 　at PK=800MeV/cEnhancement of Λ* production

at θn=0BackGround from Σ* will be reduced

Σ*

S-wave KbarN scattering is dominant at θn = 0 degree

Possible decomposition of I=0 amplitude.

Purely I=0