![Page 1: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/1.jpg)
Hiroaki OhnishiRIKEN
For the J-PARC E15 collaboration
A search for deeply bound kaonic nuclear states
by in-flight 3He(K-,n) reaction
ストレンジネスとエキゾティクス・理論の課題 March 1-3 2007 Toba
![Page 2: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/2.jpg)
A search for deeply bound kaonic nuclear states
Direct production of K-pp cluster via Direct production of K-pp cluster via 33He(K-,n) reactionHe(K-,n) reaction
K-3He K-pp
clusterneutron
reaction
Missing mass
spectroscopy
???
Decay?
Goal for the experiment J-PARC E15Goal for the experiment J-PARC E15 To answering the basic questionTo answering the basic question
: whether the deeply bound state really exists?: whether the deeply bound state really exists?
![Page 3: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/3.jpg)
Possible K-pp decay mode
K-ppcluster
FINUDA
fit region
K -pp??
Phy
s. R
ev. L
ett.
94, 2
1230
3 (2
005)
Invariant mass reconstruction
+-p-+p
K-pp2370 MeV
2275 MeV
2267 MeV
0p
p
2131 MeV
2054 MeV
p
p
-
p decay mode
Dominant Decay mode
= YN
p
p
-
p decay modeB.E. = 115 MeV
![Page 4: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/4.jpg)
Formation of K-pp via 33He(K-,n) reactionHe(K-,n) reaction
K-3He K-pp
clusterneutron
Missing mass
reaction
decay
This mode allows us to investigate K-pp cluster with both missing mass and invariant mass spectroscopy
p
p
-
Only charged particles in final state
Invariant
mass
![Page 5: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/5.jpg)
Detector concept• Missing mass spectroscopy with forward going neutron
• Bound state tagging with the measurement of decay product – Good charged particle detection efficiency– Good charged particle momentum resolution
K- beam momentum used for the experiment 1 GeV/c
In the case, if B.E. = 100 MeV ( FINUDA case)
Momentum of outgoing neutron will be 1.3 GeV
reconstruction will be crucial for this measurement
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E15 DetectorExperiment will be performed atK1.8BR beam line.
Neutron counter
Cylindrical detector systemCDH
CDC
Solenoid Magnet
K-Proton
Proton
GEANT4 detector simulation
B.E. = 100 MeV
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• Expected decay mode for K-pp – K-pp Λp pπ-p ➾ ➾– K-pp ➾ 0p ➾ Λp ➾ pπ-p
• Assume K-pp= 60 MeV
Invariant mass of Λp (MeV)
∑ channel Λ channel
Expected detector performance
p
p
-
p decay mode
p
p
-
p decay mode
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Possible K-pp decay mode(2)
+-p-+p
K-pp2370 MeV
2275 MeV
2267 MeV
0p
p
2131 MeV
2054 MeV
Back to the beginning
Akaishi-Yamazaki predictionbased on (1405) as KN bound state
Y.Akaishi & T.Yamazaki, PLB 535(2002) 70.
Question
BR( K-pp → p)BR( K-pp → YN)
1) Can we identify K-pp bound state only from missing mass?
= ???
In this case,K-pp can be decay to
mode
p
np
p
p
YN mode
0p
p
+
2) How to tag formation of K-pp bound state via decay product?
Hyperon production
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Concerning on the decay mode of K-pp →p
• Can we use +- from target region as a tag of decay ?
mode
p
np
p
p
K-pp decay mode pn p
n
n from decayp
+
--
+
n from decay
n
proton cannotescape from target
Still need to investigate
![Page 10: Hiroaki Ohnishi RIKEN For the J-PARC E15 collaboration A search for deeply bound kaonic nuclear states by in-flight 3 He(K -,n) reaction ストレンジネスとエキゾティクス・理論の課題](https://reader035.vdocuments.net/reader035/viewer/2022062517/56649f065503460f94c1b879/html5/thumbnails/10.jpg)
Summary
• J-PARC E15 experiment– Search for simplest deeply bound kaonic nucl
ear state, K-pp bound state via 33He(K-,n) reactionHe(K-,n) reaction
• Detector construction is in progress
• Experiment will be ready before Dec. 2008
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Λ
Λ momentum (MeV/c) momentum (MeV/c)
K-pp state
σ(
MeV
)
σ(
MeV
)
• Expected decay mode for K-pp – K-pp Λp pπ-p ➾ ➾– K-pp ➾ 0p ➾ Λp ➾ pπ-p
• Assume K-pp= 60 MeV
Invariant mass of Λp (MeV)
∑ channel Λ channel
Expected detector performance
p
p
-
p decay mode
p
p
-
p decay mode