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Search for double strangeness dibaryons at J-PARC. F.Sakuma, RIKEN. Strangeness in the Universe @ ECT*, 21-25, Oct, 2013. Idea from Prof. P. Kienle. P.Kienle, ECT* 2006. Outline. S=-2 dibaryon double kaonic nuclear state, K - K - pp H-dibaryon Experimental search at J-PARC - PowerPoint PPT Presentation
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Search for double strangeness dibaryons
at J-PARC
F.Sakuma, RIKEN
1Strangeness in the Universe @ ECT*, 21-25, Oct, 2013.
Idea from Prof. P. Kienle
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P.Kienle, ECT* 2006
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• S=-2 dibaryon–double kaonic nuclear state, K-K-pp–H-dibaryon
• Experimental search at J-PARC–pbar+3He annihilation at rest
• Summary
4
Outline
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Motivation: Embedding strangeness (K-) in Nucleus
• Light mesons– play an important role in a
nucleus as “glue”
• Light S=-1 mesons?– Kaonic-atom experiments (KpX@KEK,
DEAR/SIDDHARTA@DANE) clarified stronglystrongly attractive Kbar-N interaction
– What will happen when Kbar is embedded in nucleus?• Kbar-nucleus bound state?• high density?
Kaonic Nuclear Cluster (KNC)
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Kaonic nucleus is a bound state of nucleus and anti-kaon (KbarNN, KbarNNN, KbarKbarNN, ...)
Y.Akaishi & T.Yamazaki, PLB535, 70(2002).
Koike and Harada, PRC80(2019)055208
All works predict existence of the K-pp However, B.E. and are NOT converged yet.
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Recent Experimental Results
HADES@GSINPA914(2013)60
p + p ( + p) + K+ @ 3.5GeV
KK--pp searchpp search
d(+, K+) @ 1.7GeV/c
E27@J-PARC17th PAC meeting (Sep. 2013)
Ratio of proton tag / inclusive
Experimental situation is also controversial !!!
In addition to the FINUDA & DISTO results,
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J-PARC E15 Experimentsearch for the K-pp using 3He(in-flight K-,n) reaction
The latest results were given inM.SatoM.Sato’s talk
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“Double-KaonicNuclear Cluster”
What will happen to put one more kaon in the kaonic nuclear cluster?
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Double-Kaonic Nuclear Cluster (DKNC)The double-kaonic nuclear clusters were also predicted theoretically.
PL,B587,167 (2004).
The double-kaonic clusters have much stronger binding energy much higher densitythan single ones. (AMD calc.)
ppn
ppnK-
ppnK-K-
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Theoretical CalculationsM.Hassanvand, Y.Akaishi,T.Yamazaki
N.Barnea, A.Gal, E.Z.Liverts
PRC84(2011)015204, Proc.Jpn.Acad.Ser.B87(2011)362
PLB712(2012)137.
Deeply bound & CompactB=50~200MeV, ~75MeV
NOT Deeply bound & NOT CompactB~30MeV, ~80MeV
Chiral ModelHyperspherical basis
* ansatzVariational Calc.
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Theoretical Calculations (Cont’d)S.Maeda, Y.Akaishi, T.Yamazaki
arXiv:1307.3957
Deeply bound & CompactB=100~200MeV
* ansatzFaddeev Calc.
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S=-2 Dibaryon State?
K
p p
K
Kp p
K
Loosely bound KLoosely bound K--KK--pppp Deeply bound KDeeply bound K--KK--pppp
uu
d
ds
s
Excited H (H*)Excited H (H*)
u
u
d
d
s s
H-dibaryonH-dibaryon
?=
??
• the K-K-pp is loosely or deeply bound state?• the H-dibaryon exists also?
• Stable SU(3)f singlet 6-quark (uuddss) state
– proposed by R.Jaffe in 1977
• The existence is NOT confirmed experimentally
– Many experimental searches were performed– Several candidate dibaryon decays were
observed but not confirmed in the 1990s
• From the results of several double- hypernuclear events, the H is suggested to be very loosely bound (<7MeV) or unbound (~2m) state
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H-dibaryon
• Recent lattice-QCD calculations have reported evidence for the existence of the H– NPLQCD Collab. PRL106, 162001(2011).
– HAL Collab. PRL106,162002(2011).
• However, B.E. is depend on physical quark masses
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Lattice-QCD Calculations
P. E. Shanahan, A.W. Thomas, and R. D. Young, PRL107,092004(2011)., arXiv:1308.1748
loosely bound state or unbound state ~m?
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H search @ (K-,K+)
J-PARC E42
15th PAC
KEK-PS E522PRC75,022201(R) (2007).
12C(K-, K+)X @ 1.67GeV/c
Hints of the H-dibaryon as a resonance?
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H search @ B-factoryBelle PRL110,222022(2013).Inclusive (1s)(2s) decays
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H search @ HI-collisionSTAR @ RHIC
NPA914,410(2013).
Au+Au @ sqrt(sNN) = 200GeV
Experimental Approaches to Search for S=-2 dibaryons
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How to produce the S=-2 dibaryons?(K-,K+) reactionHeavy-ion collisionHeavy-meson decayp+p reactionpbarA annihilationdbarA annihilation
We perform exotic states searchWe perform exotic states search using pusing pbarbarA annihilation at J-PARCA annihilation at J-PARC
J-PARC
RHIC/LHC
BELLE
J-PARC?
J-PARC?
J-PARC/FAIR
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“S=-2 Dibaryon” SearchUsing
pbar+3He annihilation at rest
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Experimental Principle
0K K final state:
p p
We can investigate S=-2 dibaryonWe can investigate S=-2 dibaryon with inclusive with inclusive oror exclusive measurement exclusive measurement
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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
They did NOT observe any double-strangeness event in pbar - C, Ti, Ta, Pb annihilation (~80,000 events, p < 400 MeV/c)
Reaction Frequency (90% C.L.)
ppbarbarAA0000XX <4x10<4x10-4-4
pbarA0K-X <5x10-4
ppbarbarAAKK++KK++XX <5x10<5x10-4-4
ppbarbarAAHXHX <9x10<9x10-5-5
[Phys.Lett., B144, 27 (1984).]
several groups reported double-strangeness productionin pbar+A annihilation
hydrogen bubble-chamber experiment @ BNLhydrogen bubble-chamber experiment @ BNLH-dibaryon search
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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
experiment Channel # of events yield (x10-4)
DIANA@ITEPDIANA@ITEP[pbar+Xe]
PLB464, 323 (1999).
K+K+X 4 0.31+/-0.16
K+K0X 3 2.1+/-1.2
OBELIXOBELIX@CERN/LEAR@CERN/LEAR
[pbar+4He]NPA797, 109
(2007).
K+K+--ps 34+/-8 0.17+/-0.04
K+K+-+n- 36+/-6 2.71+/-0.47
K+K+-n 16+/-4 1.21+/-0.29
K+K+K-nn 4+/-2 0.28+/-0.14
Although observed statistics are small,their results have indicated a high yield of ~10-4
Expected K-K-pp Cross-Section?
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--- the K-K-pp is assumed to be produced by ** collision ---
double-strangeness production yield in pbarA: ~ 10-4
free * production yield: ~ x0.1
free ** production yield: ~ (x0.1)x(x0.1)
** production yield in pbarA: ~ 10-6
even if all ** become the K-K-pp state,K-K-pp production yield in pbarA: ~ 10-6
small production yield is expected …small production yield is expected …moreover, Q-value of ** production in pbar3He reaction is negative (Q = -55MeV)
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Experimental Strategy
I.I. investigation of investigation of “double-strangeness “double-strangeness production”production” in p in pbarbar++33He annihilation at restHe annihilation at rest
II.II. toward search for toward search for “S=-2 dibaryons” “S=-2 dibaryons” in in ppbarbar++33He annihilation at restHe annihilation at rest
present situation of the double-strangeness production in pbar+A (A>1) annihilation at rest:NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments.high-statistics measurement is NOT performed!
26
Experimental SetupWe will perform the experiment at J-PARC K1.8BR beam lineWe will perform the experiment at J-PARC K1.8BR beam line
stopped-pstopped-pbarbar beam beaminitial beam mom. of 0.7GeV/c w/ tungsten degrader (t=31mm)
~750/spill(6s) @ 50kW, Au-target
pp--
pIDpID
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Double-Strangeness Measurement
K+K+X channel X channelK+K+
detection 20% detection 6.8%
evaluated using GEANT4 toolkitMany-body decay are considered to be isotropic decay.branching ratios of K0K0
S/K0S/p are considered.
acceptance is defined by IH and CDC mid layer (R<350mm)
acceptances of Kacceptances of K++KK++ and and
e.g. acceptance of IH+CDC(R<350mm)
1
10
100
1.E-06 1.E-05 1.E-04 1.E-03st
atisti
cal s
igni
fican
ce (s
)production ratio (/stopped-pbar)
K+K+ΛΛ3σ line
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Double-Strangeness Measurement (Cont’d)
uptime of the accelerator and apparatus : 21h/24hDAQ and analysis eff. : 0.7
sensitivitysensitivity 50kW, 2weeks
DIANA/OBELIX
K+K+: ~540: ~160
1st production run (2013, May.)
pp--pIDpID
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Experimental Strategy
I.I. investigation of investigation of “double-strangeness “double-strangeness production”production” in p in pbarbar++33He annihilation at restHe annihilation at rest
II.II. toward search for toward search for “S=-2 dibaryons” “S=-2 dibaryons” in in ppbarbar++33He annihilation at restHe annihilation at rest
present situation of the double-strangeness production in pbar+A (A>1) annihilation at rest:NO results with a dedicated spectrometer and high intensity beam except for bubble chamber experiments.high-statistics measurement is NOT performed!
30
Procedure of S=-2 Dibaryons Search
possible methods of the measurementpossible methods of the measurement(inclusive) invariant mass(inclusive) K0K+ missing-mass w/ -tag(exclusive) K0K+ measurement
evaluated using GEANT4 toolkitisotropic decaybranching ratios of K0K0
S/K0S/p
are considered.
acceptanceacceptance K-K-ppB.E. = 120MeV= 100MeV
100%
Hm = m+10MeV
= 10MeV100%
detection 14.5%
detection 3.6%
K+K0 0.8% K+K0 3.6%
K+K0 0.3% K+K0 0.4%
e.g. acceptance of IH+CDC(R<350mm)
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Background Assumptions• 2N abs.
– K+ K+ K- 0 ns
– K+ K+ K0bar - ns
– K+ K+ K- - ps
– K+ K+ - ns
– K+ K0 K0bar 0 ns
– K+ K0 K- + ns
– K+ K0 K- 0 ps
– K+ K0 K0bar - ps
– K+ K0 0 ns
– K+ K0 - ps
• 3N abs.– K+ K+ - / -
– K+ K0 / 0
– K+ K0 0 0 -
– K+ K0 0 / 0
– K+ K0 0 0 0 +- 0
* Not consider N
• Production ratios are assumed to be:– 2N:3N = 4:1, and total ratio
= 5*10-4 (upper lim.)
• 2N abs.: 4*10-4
• 3N abs.: 1*10-4
– exotics: parameter
• 6weeks @ 50kW, Au-target (50%)– uptime = 21h/24h– detector/trig. eff. = 0.7
Expected Spectra w/ IH+CDC(R<350mm)
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KK++KK00 M.M. M.M. I.M.I.M.
K-K-pp10-5/stopped-pbar
B.E. = 120MeV= 100MeV
= 1:1:2
H10-5/stopped-pbar
m = m+10MeV = 10Mev100%
Expected Spectra w/ full-CDC
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KK++KK00 M.M. M.M. I.M.I.M.
K-K-pp10-5/stopped-pbar
B.E. = 120MeV= 100MeV
= 1:1:2
H10-5/stopped-pbar
m = m+10MeV = 10Mev100%
1
10
100
1.E-06 1.E-05 1.E-04
stati
stica
l sig
nific
ance
(s)
production ratio (/stopped-pbar)
KKpp (CDC)H (IH)3σ line
We would reach sensitivities of less than 10We would reach sensitivities of less than 10-5-5 (3 (3ss))[Expected: K-K-pp ~ 10-6 / H < 9*10-5]
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Sensitivity
inclusive inclusive measurement measurement50kW, 6weeks
K-K-ppB.E. = 120MeV= 100MeV
= 1:1:2
Hm = m+10MeV
= 10Mev100%
35
SummaryS=-1 Dibaryon Search by S=-1 Dibaryon Search by 33He(He(in-flightin-flightKK--,n)K,n)K--pp:pp:The E15 experiment started 1st-stage physics-run.
S=-2 Dibaryon Search in pS=-2 Dibaryon Search in pbarbar++33He annihilation at rest:He annihilation at rest: double-strangeness measurement will be conducted as a first
step measurement of 33He(pHe(pbarbar, , )X )X reaction would give us some
hints of the KK--KK--pp/Hpp/H productions