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Studies of exotic baryons with hadron beams at J-PARC

Hiroyuki NoumiRCNP, Osaka Univ./IPNS, KEK

RHIQCD2016 Symposium@YITP, Nov. 28, 2016

Today’s Exotic Baryons

• L(1405)

– With a Low-E Kaon beam

• KbarN interaction and exotic hyperon

– With a High-E pion beam

• production and exotic hyperon

• 𝑃𝑐0

– With a High-E pion beam

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Still L(1405)?

• KbarN int. and its pole position are still unclear.

– Basic information on Kaonic Nuclei

• Not yet demonstrated if it is a molecular state.

– Needed to establish it as an exotic state

• Hadron Picture in excited states

• New question related to classification in CQM

– Formation probability in hadronization

• ExHIC (Phys.Rev. C84 (2011) 064910)

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measuring an S-wave ഥ𝐾𝑁 → πΣ scattering below the ഥ𝐾𝑁threshold in the d(K-,n)pS reactions at a forward angle of n.

E31 aims at:

ID’s all the final states to decompose the I=0 and 1 ampl’s.

K-

d

n

ഥ𝑲 𝝅∓,𝟎

𝜮±,𝟎𝑵

𝑵

𝝅±𝚺∓ I=0, 1 L(1405) (I=0, S wave), non-resonant[I=0/1](S(1385) (I=1, P wave) to be suppressed)

𝝅−𝚺𝟎

[𝝅−𝚲]I=1 non-resonant (S(1385) to be suppressed)

d(K-,p)p-S0 [p-L]

𝝅𝟎𝚺𝟎 I=0 L(1405) (I=0, S wave), non-resonant

Ushiwaka

CDS

D5

NCPC

K-n

d L(1405)

n

1 GeV/c ~1.25 GeV/c

~0.25 GeV/c

Cylindrical Detector System(Solenoid Field 0.7T)

K- Beam Spectrometer(K1.8BR-D5)

Beam Sweeper(Ushiwaka)

Neutron

Counter (NC)

TOF~15m

ProtonCounter (PC)

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Experimental Setup for E31

Sp

p

CDCT0

BHDBLC2

BLC1

BPDBPC

CDH

Schematic Drawings of Detectors

• Event topology of 𝑑 𝐾−, 𝑛 𝑋𝜋±Σ∓

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𝚺−(𝚺+)

NC

CDS𝝅−(𝝅+)

𝐧𝐊−

~15 m

CDC

CDC

n

BPD

T0

Solenoid mag.

𝝅+(𝝅−)

𝜋+Σ−/𝜋−Σ+ Mode (𝐼 = 0, 1)

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𝜋−Σ+

𝜋+Σ−++

𝑑𝜎

𝑑Ω𝜋±Σ∓ =

1

3𝑓𝐼=0

2 +1

2𝑓𝐼=1

2 ±6

3𝑅𝑒(𝑓𝐼=0𝑓𝐼=1

∗ )𝑑2𝜎

𝑑Ω𝑑𝑀𝜋Σ

(Arb

itra

ry U

nit

)

Schematic Drawings of Detectors

• Event topology of 𝑑 𝐾−, 𝑝 𝑋𝜋−Σ0

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PC

CDS𝝅−

𝐩𝐊−

~15 m

CDC

CDC

p

BPD

T0

Solenoid mag.

𝝅−

𝚺𝟎

g

9

𝜋+Σ−/𝜋−Σ+ Average (𝐼 = 0, 1)V.S. 𝜋−Σ0 Mode (𝐼 = 1)

𝑑𝜎

𝑑Ω𝑑𝑀𝜋Σ

(Arb

itra

ry U

nit

)

• The I=0 amplitude seems dominant.1

2× 𝜋+Σ− + 𝜋−Σ+

~1

3𝑓𝐼=0

2 +1

2𝑓𝐼=1

2

1

2× 𝜋−Σ0 ~

1

2𝑓𝐼=1

2

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Λ(1405) : 1405.1+1.3-1.0 MeV (PDG Part. List’gs)

JP = ½-, I = 0, ML(1405)< MKbarN , lightest in neg. parity baryons

Pole Structure of the Lambda(1405) RegionPDG Reviews: Ulf-G. Meissner and T. Hyodo (Nov. 2015)

J. Esmaili et al: pS IM Spec. of Stopped K- on 4He

R.H. Dalitz et al: pS IM Spec. in K-p→ππΣ w/ M-matrix

M. Hassanvand et al: pS IM Spec. of pp→K+pS

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𝜋+Σ−/𝜋−Σ+ Average (𝐼 = 0, 1)V.S. 𝜋−Σ0 Mode (𝐼 = 1)

𝑑𝜎

𝑑Ω𝑑𝑀𝜋Σ

(Arb

itra

ry U

nit

)

• The I=0 amplitude seems dominant.1

2× 𝜋+Σ− + 𝜋−Σ+

~1

3𝑓𝐼=0

2 +1

2𝑓𝐼=1

2

1

2× 𝜋−Σ0 ~

1

2𝑓𝐼=1

2

1405

1421~1434

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Remarks of E31 1st Run

• Structures below and above the ഥ𝐾𝑁 threshold are observed in 𝑑 𝐾−, 𝑛 𝑋𝜋±Σ∓

– Interference btw I=0 and 1.

• Pure I=1 channel, 𝑑 𝐾−, 𝑝 𝑋𝜋−Σ0, is observed.

– I=0 amp. seems dominant in 𝜋±Σ∓ modes, assuming similarity of the reaction mechanism among 𝑑 𝐾−, 𝑛 𝑋𝜋±Σ∓ and 𝑑 𝐾−, 𝑝 𝑋𝜋−Σ0.

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In E31 2nd Run

• To measure a Pure I=0 channel, 𝑑 𝐾−, 𝑛 𝑋𝜋0Σ0

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𝚺𝟎

NC

CDS𝝅−

𝐧𝐊−

~15 m

CDC

CDC𝜋0

γ

p

BPD

T0

Solenoid mag.

0.2

0.4

0.6

0.8

1

0.3 0.4 0.5 0.6 0.7

|<f|

j 0(q

effr

)|i>

|2 (n

orm

aliz

ed)

qeff [GeV/c]

Further studies on L(1405)• Angular dependence of 𝑑 𝐾−, 𝑛 𝑋(𝜋Σ)0

– “Sticking probability” of ഥ𝐾 to a residual 𝑁

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𝐼(𝑞𝑒𝑓𝑓; 𝑏0) = | 𝑓(𝑏0) 𝑗0(𝑞𝑒𝑓𝑓𝑟/ℏ) 𝑖 |2

𝑓 𝑏0 ~𝑁exp(−𝑟2/𝑏02): S wave final state

𝑞𝑒𝑓𝑓: mom. transfer (angular dependent)

The larger 𝑏0, the steeper angular dependence.

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5

exp

(-r2

/b0

2)

j 0(q

effr

)

r [fm]

q=0.3 GeV/c

q=0.4 GeV/c

b0=2 fm

b0=1fm

Further studies on L(1405)

• L(1405) production in Hard process (at large s, t) :

– quark counting rule: 𝑑𝜎/𝑑Ω|𝜃=90𝑜~ 1/𝑠𝑛−2

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H. Kawamura, et al.PRD 88, 034010 (2013)

𝜋− + 𝑝 → 𝐾− + Λ(1405)

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High-res., High-momentum Beam Line

30 GeV

proton beam

Production

Target

Pion BeamUp to 20 GeV/c

Spectrometer

T1

• High-intensity secondary Pion beam (unseparated)– 1.0 x 107 pions/sec @ 20GeV/c

• High-resolution beam: Dp/p~0.1%

K+

p-

ps-

decayp(p+)

RICH

ITOF

FiberTracker

DCDC

DCTOF

H2 TGT

c

qq

D0(Yc’)

p(p)

Inclusive p(p-,D*-) Yc*+

p(p-,D*-p)D0

Yc*+

( p(p-,D*-p)Yc’ )

(Target)

Charmed Baryon

In Summary

• A low-E Kbar beam is used for studying hyperon resonances below KbarN threshold.– 𝑑 𝐾−, 𝑛 𝑋𝜋±Σ∓ demonstrates an S-wave ഥ𝐾𝑁 → πΣ scattering,

showing the I=0 dominance.– A structure around the KbarN threshold is observed.– A pole position will be determined by the spectra.

• Further studies are necessary:– 𝑑 𝐾−, 𝑛 𝑋𝜋0Σ0 will be measured next year.– Meas. of Angular distribution → form factor (under

consideration)– L(1405) production in Hard process will be measuredat the

high-p beam line at J-PARC, which may give “# of quarks” in it.

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