Search for Exotic Hadrons, Hdibaryon resonance and Pentaquark

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Search for Exotic Hadrons, Hdibaryon resonance and Pentaquark

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SCIFI active target. Performances / Results. 214. 151 events, 12C(K-,K LLX) Analyzed ... SCIFI , CH2 data are combined. No clear peak. CH2 data. A bump around 1. ... – PowerPoint PPT presentation

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Title: Search for Exotic Hadrons, Hdibaryon resonance and Pentaquark

1
Search for Exotic Hadrons, H-dibaryon resonance
and Pentaquark

K.Imai (Kyoto Univ.)
for KEK-PS E522 collaboration
Introduction
KEK-PS E522 experiment
H-dibaryon resonance by C(K-,KLL) reaction
Pentaquark, Q, by p- p -gt K- Q
Summary

2
LL-Enhancement by the KEK-E224
J.K.Ahn et al., Phys. Lett. B444,267(1998)
(1) H-dibaryon Resonance? K-p-gtX-K
X-(p) -gt H, H-gtLL

(2) Strong LL Final State Interaction?

3

Can we understand Consistently ?

6HeLL
DBLL1.01 MeV

4

M.Hyata, H.Sato a)
J.Asai, M.Kurosawa b)
M.Kurosawa b)
M.Ieiri, H.Takahashi c)

, B.H.Choi g)

5
-
SCIFI active target
20 cm
6
Performances / Results
214
151 events, 12C(K-,KLLX) Analyzed
7
(No Transcript)
8
Real Data
Simulation Data
9
LL-Invariant Mass
S 9 s to the Combinatorial S3 s to the
INCfss2(QCM)
fss2 well reproduce BLL(6LLHe) 1. MeV

10
Conclusion 1

We have confirmed the peak near threshold in LL
mass spectrum previously observed by E224 with
higher statistics.
The data can not be explained with final state
interaction which is consistent with weak
attractive LL binding energy determined from
the mass of 6HeLL.
The H-dibaryon resonance is a possible
interpretation of the peak. More theoretical
input is needed as well as experiments.
Data Analysis was done by C.J.Yoon (Kyoto)

11
Pentaquark search in KEK-PS E522

Objectives of E522
H-dibaryon resonance search via (K-,K) reaction
Kaonic Nuclei search via (K-,p) reaction
Q search via (p-,K-) reaction (as extra)

3days
12
Missing mass spectrum of (?,K) reaction

Inverse reaction of (?-,K-)
Observe ? peak

13
Missing mass spectrum of (??,K?)
P?1.87GeV/c
P?1.92GeV/c
CH2 data A bump around 1.53GeV/c2 Statistical
fluctuation?
SCIFI , CH2 data are combined No clear peak
14
Fitting of spectrum

Peak position
Width
Counts 182.5?70.8(stat.) ?9.9(syst.)
Statistical significance 2.52.7?
Upper limit of peak count N? lt 298.3(90 C.L.)

15
Upper limit of cross section

fbeam83(e,? contamination 13,
? reaction 4)
eK272.3
eDAQ94
fKabs89.8
etrack84.6
fdecay57.6
fcherenkov91
eMT95.7
eana51
d?0.14sr

16
Conclusion 2

We have searched for Pentaquark Q by p- p -gt K-
Q reaction at KEK-PS
A peak of 2.6 s was observed at 1531 MeV.
Upper limit of the production cross section was
obtained to be about 4 mb which is smaller than
most of theoretical calculations.
(The analysis was done by K.Miwa (Kyoto))

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