Post on 13-Jun-2020
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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
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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
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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
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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