A search for double anti-kaon production in antiproton- 3 He annihilation at J-PARC
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A search for double anti-kaon production in antiproton-3He
annihilation at J-PARC
Fuminori Sakuma, RIKEN
1Strangeness in Nuclei @ ECT*, 4-8, Oct, 2010.
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This talk is based on the LoI submitted in June, 2009.
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Possibility of “Double-Kaonic Nuclear Cluster”
by Stopped-pbar AnnihilationExperimental ApproachSummary
Contents
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Possibility of“Double-Kaonic Nuclear Cluster”
by Stopped-pbar Annihilation
What will happen to put one more kaon in the kaonic nuclear cluster?
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Double-Kaonic Nuclear ClusterThe double-kaonic nuclear clusters have been predicted theoretically.The double-kaonic clusters have much stronger binding energy and a much higher density than single ones.
B.E. [MeV] Width [MeV]
Central-Density
K-K-pp -117 35
K-K-ppn -221 37 17r0
K-K-ppp -103 -
K-K-pppn -230 61 14r0
K-K-pppp -109 -
How to produce the double-kaonic nuclear cluster?heavy ion collision(K-,K+) reactionpbarA annihilation
We use pbarA annihilation
PL,B587,167 (2004). & NP, A754, 391c (2005).
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p p K K K K
The elementary pbar-p annihilation reaction with double-strangeness production:
This reaction is forbidden for stopped pbar, because of a negative Q-value of 98MeV
Double-Strangeness Production with pbar
If multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions would be possible!
-98MeV
3
3 0
4
4 0
106MeV
109MeV
126MeV
129MeV
pnKK
ppKK
pnnKK
ppnKK
p He K K K K pn B
p He K K K K pp B
p He K K K K pnn B
p He K K K K ppn B
- -
- -
- -
- -
-
-
-
-6
theoreticalprediction
B.E.=117MeVG=35MeV
B.E.=221MeVG=37MeV
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K-K-pp in pbar+3He annihilation at rest?
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The possible mechanisms of the K-K-pp production are as follows:1: direct K-K-pp production with 3N annihilation1’: L*L* production with 3N annihilation followed by the K-K-
pp formation2: elementally pbar+pKKKK production in nuclear matter
followed by the K-K-pp formationHowever, there are many unknown issues, like:
1: non-resonant LL is likely to be produced compared with the K-K-pp formation!
1’: how large is the L*L* binding energy, interaction?2: is it possible?
Anyway, if the K-K-pp exists, we can extrapolate simply the experimental results of the K-pp:
FINUDA@DAFNE B.E. ~ 120 MeV, G ~ 70 MeVDISTO@SATURNE B.E. ~ 100 MeV, G ~ 120 MeV
then, we can assume the double binding strength:B.E ~ 200 MeV, G ~ 100 MeV.
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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation
A result of a search for double-strangeness productions in antiproton-nuclei annihilations was reported by using the BNL bubble chamber, in association with the H-dibaryon search.
They did NOT observe any double-strangeness event in antiproton - C, Ti, Ta, Pb annihilation
(~80,000 events, p(pbar) < 400 MeV/c)
Reaction Frequency (90% C.L.)
pbarAL 0L 0X <4x10-4
pbarAL 0K-X <5x10-4
pbarAK+K+X <5x10-4
pbarAHX <9x10-5
[Phys.Lett., B144, 27 (1984).]
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Past Experiments (Cont’d)
Observations of the double-strangeness production in stopped pbar annihilation have been reported by 2 groups, DIANA@ITEP and OBELIX@CERN/LEAR.
experiment channel events yield (10-4)
DIANA K+K+X 4 0.31+/-0.16[pbar+Xe] K+K0X 3 2.1+/-1.2
K+K+S-S-ps 34+/-8 0.17+/-0.04
OBELIX K+K+S-S+np- 36+/-6 2.71+/-0.47[pbar+4He] K+K+S-L n 16+/-4 1.21+/-0.29
K+K+K-L nn 4+/-2 0.28+/-0.14
Although observed statistics are very small,their results have indicated a high yield of ~10-4
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Past Experiments (Cont’d)DIANA [Phys.Lett., B464, 323 (1999).]pbarXe annihilationp=<1GeV/c pbar-beam @ ITEP 10GeV-PS700-liter Xenon bubble chamber, w/o B-field106 pictures 7.8x105 pbarXe inelastic 2.8x105 pbarXe @ 0-0.4GeV/c
Channel events yield (10-4)
K+K+X 4 0.31+/-0.16
K+K0X 3 2.1+/-1.2
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channel events yield (10-4)
K+K+S-S-ps 34+/-8 0.17+/-0.04
K+K+S-S+np- 36+/-6 2.71+/-0.47
K+K+S-Ln 16+/-4 1.21+/-0.29
K+K+K-Lnn 4+/-2 0.28+/-0.14
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Past Experiments (Cont’d)OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).]pbar4He annihilationstopped pbar @ CERN/LEARgas target (4He@NTP, H2@3atm)cylindrical spectrometer w/ B-fieldspiral projection chamber,
scintillator barrels, jet-drift chambers2.4x105/4.7x104 events of 4/5-prong in 4Hepmin = 100/150/300MeV/c for p/K/p
they discuss the possibility of formation and decay of K-K-nn and K-K-pnn bound system
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K-pp Production with pbar at rest
3 0p He K K pp-
We can also measure K-pp productionwith the dedicated detector, simultaneously!
Our experiment can check the OBELIX results of the K-pp with a dedicated spectrometer
OBELIX@CERN-LEARNP, A789, 222 (2007).EPJ, A40, 11 (2009).
K-pp?
4
p He K pp X
p
- L
B.E. = -151.0+-3.2+-1.2 MeVG< 33.9+-6.2 MeVprod. rate > 1.2 x 10-4
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H-dibaryon search with pbar at rest
3 0
p He K K H
L L
We can also search for H-dibaryon (H-resonance) by using LL invariant mass / missing mass:
E522@KEK-PS
Phys. Rev., C75 022201(R) (2007).
H?
12 ,C K K X- LL
The upper limit for the production cross section of the H with a mass range between the LL and XN threshold is found to be 2.1 +- 0.6 (stat.) +- 0.1 (syst.) mb/sr at a 90% confidence level.
the exclusive measurement has never been done using stopped pbar beam.
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Experimental Approach
The double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems.
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How to Measure?
3 0 ( )p He K K X X K K pp - - we focus the reaction:
(although K-K-pp decay modes are not known at all,)we assume the most energetic favored decay mode:
K K pp- - L L
We can measure the K-K-pp signal exclusively by detection of all particles, K+K0LL, using K0p+p- mode
final state = K+K0LL
We needwide-acceptance detectors.
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Expected Kinematicsassumptions:widths of K-K-pp = 0isotropic decay
3 0Sp He K K K K pp - -
B.E=120MeV B.E=150MeV B.E=200MeV(th.+11MeV)
In the K-K-pp production channel, the kaons have very small momentum of up to 300MeV/c, even if B.E.=200MeV.
We have to construct low mass material detectors.
K+K0X momentum spectra
~70MeV/c Kaon ~150MeV/c Kaon ~200MeV/c Kaon
~200MeV/c p from K0S, ~800MeV/c L, ~700MeV/c p from L, ~150MeV/c p- from L
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Procedure of the K-K-pp Searchkey points of the experimental setuphigh intensity pbar beamlow mass material detectorwide acceptance detector
methods of the measuremt(semi-inclusive) K0
SK+ missing-mass w/ L-tag(inclusive) LL invariant mass(exclusive) K0
SK+LL measurement
K1.8BR Beam Line
neutron
Beam trajectory
CDS &target
SweepingMagnet
NeutronCounter
Beam LineSpectrometer
The E15 spectrometer at K1.8BRsatisfies the above requirements
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Detector Acceptance
E15 CDS @ K1.8BR
stopped-pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00
0.05
0.10
0.15
acce
ptan
ce
--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
binding energy
9.0%
3.5%
0.8%
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pbar Beam @ J-PARC K1.8BRWe would like to perform the proposed experiment
at J-PARC K1.8BR beam line
pbar stopping-rate
50kW, 30GeV6.0degreesNi-target
pbar production yield with a Sanford-Wang +
a pbar CS parameterization
250 stopped pbar/spill@ 0.7GeV/c, ldegrader~3cm
Incident Beammomentum bite : +/-2.5% (flat)incident beam distribution : idealDetectorsTungsten Degrader : r=19.25g/cm3
Plastic Scintillator : l=1cm, r=1.032g/cm3
Liquid He3 target : f=7cm, l=12cm, r=0.080g/cm3
pbar stopping-rate evaluation by GEANT4
6.5x103/spill/3.5s @ 0.7GeV/c
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Expected double-strangeness Production Yieldpbar beam momentum : 0.7GeV/cbeam intensity : 6.5x103/spill/3.5s @ 50kWpbar stopping rate : 3.8%
stopped-pbar yield : 250/spill/3.5s
we assume: double-strangeness production rate = 10-4
duty factors of the accelerator and apparatus = 21h/24h
double-strangeness production yield = 540 / day @ 50kW [1day= 3shifts]
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Trigger Scheme
pbar3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 (1990).
Nc Branch (%)
1 5.14 +/- 0.04
3 39.38 +/- 0.88
5 48.22 +/- 0.91
7 7.06 +/- 0.46
9 0.19 +/- 0.08
<Nc> 4.16 +/- 0.06
expected stopped-pbar yield = 250/spill @ 50kW
All events with a scintillator hit can be accumulated
expectedK-K-pp event
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Backgrounds(semi-inclusive) K0
SK+ missing-mass w/ L-tagstopped-pbar + 3He K0
S + K+ + K-K-pp
stopped-pbar + 3He K0S + K+ + L + L
stopped-pbar + 3He K0S + K+ + L + L + p0 …
stopped-pbar + 3He K0S + K+ + K0 + S0 + (n)
stopped-pbar + 3He K0S + K+ + X0 + (n) …
3N annihilation
2N annihilation
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Backgrounds (Cont’d)(inclusive) LL invariant mass
stopped-pbar + 3He K0S + K+ + K-K-pp
L + Lstopped-pbar + 3He K0
S + K+ + K-K-pp S0 + S0
stopped-pbar + 3He K0S + K+ + K-K-pp
S0 + S0 + p0 …
missing 2g
missing 2g+p0
B.E = 200 MeVG = 100 MeV
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Expected Spectra
expected spectra are obtained withthe following assumptions:
Monte-Carlo simulation using GEANT4 toolkitreaction and decay are considered to be isotropic and proportional to the phase spaceenergy losses are NOT corrected in the spectraw/o Fermi-motionDAQ and analysis efficiency of 0.7
total yield : upper limit of pbarAKKX, 5x10-4
3N : 20% of total yield, and 3N:2N = 1:3
K-K-pp yield : 20% of total yield
production rate:• K-K-pp bound-state = 1x10-4
• (3N) K-K-LL phase-space = 5x10-5
• (3N) K+K0S0S0p0 phase-space = 5x10-5
• (2N) K+K0K0S0(n) phase-space = 3x10-4
These are optimistic assumptions
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Expected Spectra (Cont’d)
non-mesonic : mesonic = 1 : 1
because the SSpp decay channel expected as the main mesonic branch of the K-K-pp state could decrease due to the deep binding energy of the K-K-pp
branching ratio of K-K-pp:• BR(K-K-ppLL) = 0.25• BR(K-K-ppS0S0 = 0.25• BR(K-K-pp S0S0 p0) = 0.5
mass [MeV]
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Expected Spectra @ 50kW, 6weeks (126shifts)
In the LL spectra, we hardly discriminate the K-K-pp LL signals from the backgrounds clearly, but a cocktail approach could help us to explore the K-K-pp signals?
3 0 p He K K X L L 3 0 ( )p He K K X L L
# of K-K-ppLL = 357
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 15
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Spectra @ 50kW, 6weeks (126shifts) (Cont’d)
With a single L-tag, the 2N annihilation signals could overlap with the K-K-pp one, therefore we hardly distinguish the signal from the backgrounds.
3 0 p He K K X L 3 0 ( )p He K K X L L
The exclusive K0K+ missing mass spectrum is attractive because we can ignore the 2N-annihilation, even though the expected statistics are small.
K+K0 missing mass (2KL) K+K0 missing mass (2K2L)
# of K-K-pp = 208 # of K-K-pp = 32
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0.0E+00 5.0E-05 1.0E-04 1.5E-04 2.0E-040
1
2
3
4
5
6
7
8
ppKK production rate (/stopped-pbar)
stati
stica
l sig
nific
ance
(s)
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Sensitivity to the K-K-pp signal
significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra
5.0SS B
Integratedrange
ppK-K- rate = 1x10-4
--- BKK = 200 MeV--- BKK = 150 MeV--- BKK = 120 MeV
beam power : 50kW, 6weeksproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)
4x10-57x10-5
1.1x10-4
2600 – 2760 MeV
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0.0E+00 5.0E+19 1.0E+20 1.5E+20 2.0E+201E-05
1E-04
1E-03
number of proton on target
3s si
gnifi
canc
epp
KK p
rodu
ction
rate
(/
stop
ped-
pbar
)
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Sensitivity to the K-K-pp signal (Cont’d)
significance [s=S/sqrt(S+B)] is obtained in exclusive missing-mass spectra
--- BKK = 200 MeV--- BKK = 150 MeV--- BKK = 120 MeV
beam power : parameterproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)
30kW, 6weeks
100kW, 6weeks 270kW,
6weeks
50kW, 6weeks
K-K-pp
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Sensitivity to the double-strangeness productionDon't forget that the double-strangeness production itself, in pbar+A annihilation at rest, is very interesting.(there are NO conclusive evidences)
production mechanism (multi annihilation/cascade/…)?hidden strangeness?H/XN?cold QGP? little bit old!
significance [s=sqrt(S)] of the LL is obtained in the inclusive K++K0+L+L event
0.0E+00 5.0E+19 1.0E+20 1.5E+20 2.0E+201E-08
1E-07
1E-06
1E-05
1E-04
number of proton on target
3s si
gnifi
canc
eLL
pro
ducti
on ra
te
(/st
oppe
d-pb
ar)
30kW, 6weeks 100kW,
6weeks270kW, 6weeks
50kW, 6weeks
LLOBELIX/DIANA
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Summary
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Summary
We will search for double anti-kaon nuclear bound states by pbar annihilation on 3He nuclei at rest, using the pbar + 3He K+ + K0 + X (X = K-K-pp) channel.
The produced K-K-pp cluster will be identified with missing mass spectroscopy using the K+K0 channel with a L-tag, and invariant mass analysis of the expected decay particles from the K-K-pp cluster, such as LL by using the E15 spectrometer at the K1.8BR beam line.
We are now improving this experiment toward the proposal submission to J-PARC.
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Back-Up
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Schedule
Year (JFY) K1.8BR K1.1 (fN)2009 beam-tune proposal2010 E17 R&D, design2011 E17 R&D, design2012 E15/E31 construction2013 E15/E31 commissioning2014 … data taking
The proposed experiment will be scheduled in around JFY2014, whether we conduct the experiment at K1.8BR or K1.1 beam-line.
K1.8BR : after E17/E15/E31K1.1 : joint project with the fN experiment (E29)?
here?
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L(1405)/K-pp production in pbarA annihilation at rest
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L(1405) production in pbarA annihilationthe things we have learned from the past experiments are:
1. the reactions whose quark-lines vanish are minority (Pontecorvo reactions)
pbar + d K0 + L + X pbar + d K0 + L
It would be too hard to investigate the L(1405) production using the simple channel in pbarA reaction
~10-3 ~10-6
CERN/LEAR, Crystal Barrel,Phys. Lett., B469, 276 (1999)
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2. L (1405) production yield in pbar+A annihilation can be considered as
~ 1/10 x L(S0) production yieldby analogy with the p-+p reaction
38
L(1405) production in pbarA annihilation (Cont’d)
p-+p X, pp- = 4.5 GeV/c sqrt(s) = 3.2 GeVpbar+d X, at rest sqrt(s) = 2.8 GeV
p-+p L +K : 123.5 mbp-+p S0+K : 61.5 mbp-+p L (1405)+K0 : 18 mb
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39
L(1405) production in pbarA annihilation (Cont’d)pbar+d L (S0)+X : ~3.3x10-3 per stopped-pbar
pbar+d L (S0)+K0 : ~4.5x10-6 per stopped-pbar
pbar+3He L (S0)+X : ~5.5x10-3 per stopped-pbar
pbar+d L (1405)+X : ~3x10-4 per stopped-pbar
pbar+d L (1405)+K0 : ~5x10-7 per stopped-pbar
pbar+3He L (1405)+X : ~5x10-4 per stopped-pbar
pbar+3He L (1405)+K0+ps : ~5x10-7 per stopped-pbar
extrapolate
taking account of the K0 detection efficiency of ~10-1, naively, the L* detection yield with the simple channel is the order of 10-8/stopped-pbar at least.
huge combinatorial background from involved pions could not be eliminated from L*pSppn decays, even if we can detect the neutron.
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40
K-pp production in pbarA annihilation
1 nucleon annihilation (from K-)
2 nucleon annihilation (from L(1405))
3p He p n p p
K K p p
K K p p
K K pp
p
p
p
- -
- -
- -
e.g.:
3
0
0
0
(1405)
(1405)
p He p pn p
K p
K p
K K pp
p p
p p
p p
-
-
- -
L
L
e.g.:
pL* ~ 500MeV/c
pK- ~ 900MeV/c
yield ~ 10-2
yield ~ 10-4
3 nucleon annihilation (direct production) 3p He p ppn
K K ppp - -
e.g.:
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41
K-pp production in pbarA annihilation (Cont’d)Let’s consider sticking probability R of L(1405) with proton as the following equation:
R ~ exp(-q2/pF2),
where q is the momentum transfer and pF is the Fermi motion of 3He which is ~ 100 MeV/c. If we assume q is ~ 500 MeV/c, then the probability R can be obtained to be ~ 10-11.
10th J-PARC PAC-meeting (Nagae)
However, if we apply their assumption of R ~ 1%
K-pp yield ~ 3x10-4 (L* yield) x 10-2 (sticking prob.) = 3x10-6
in pbar+3He annihilationpbar+dL*X
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42
K-pp production in pbarA annihilation (Cont’d)
B.E.=50MeV B.E.=100MeV B.E.=150MeV0.0
0.1
0.2
0.3
0.4
pbar+3He->K++p-+(K-pp)K-pp -> Lp,
G=100MeV
inv-mass (at rest)miss-mass (at rest)exclusive (at rest)inv-mass (1GeV/c)miss-mass (1GeV/c)ac
cept
ance
acceptance with the E15 CDS
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43
K-pp production in pbarA annihilation (Cont’d)mass spectra
mass resolutionL p inv-mass : ~24MeV/c2
K+p- miss-mass : ~79MeV/c2
for example• at rest• pbar3He K+p-(K-pp)• K-ppLp• B.E.=100MeV,• G=100MeV
*** production yields are assumed to be the same for each process ***
Lp invariant mass K+p- missing mass
E15 w/ n : ~13MeV/c2 for Lp inv-mass
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44
K-pp production in pbarA annihilation (Cont’d)from the past experiment (CERN-LEAR), the L production yield in pbar+3He annihilation is known to be 5.5x10-3/stopped-pbar.If we assume the ratio of 3NA/2NA is 10%, then the simplest BG pbar+3HeK+p-
Lp is ~5x10-4.beam power : 50kW, 6weeksproduction rate:• K-pp bound-state = 1x10-4
• (3N) K-p-Lp phase-space = 5x10-4
K-ppLp/S0p/p0S0p=100/0/0
50/50/0
25/25/50
from OBELIX
B.E.=100MeVG=100MeV
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in-flight experiment
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46
Detector Acceptance
E15 CDS @ K1.8BR
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
stopped1GeV/c
B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00
0.05
0.10
0.15pbar+3He->K++K0+(K-K-pp)
K-K-pp -> LL, G=100MeV
acce
ptan
ce
binding energy
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47
Expected double-strageness Production Yieldpbar beam momentum : 1GeV/cbeam intensity : 7.0x104/spill/3.5s @ 50kW
we assume K-K-pp production rate = 10-4 for 1GeV/c pbar+p (analogy from the DIANA result of double-strangeness production although the result are from pbar+131Xe reaction)
inelastic cross-section of 1GeV/c pbar+p is (117-45) = 72mb
K-K-pp production CS = 7.2mb for 1GeV/c pbar+p
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48
Expected double-strangeness Production Yield (Cont’d)
Expected double-strangeness yield = 2.1x103 /day @ 50kWw/o detector acceptance
L3He parameters: * r = 0.08g/cm3
* l = 12cmN = s * NB * NT• N : yield• s : cross section• NB : the number of beam• NT : the number of density per unit area of the target
BG rate: total CS = 117mbpbar = 7.0x104/spill BG = 1.6x103/spill
duty factors of the accelerator and apparatus = 21h/24h
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49
Expected Spectra @ 50kW, 6weeks
# of K-K-ppLL = 716
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 24
K+K0 missing mass (2KL) K+K0 missing mass (2K2L)
# of K-K-pp = 776 # of K-K-pp = 41
1GeV/c pbar
ppK-K- rate = 1x10-4
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50
Expected Spectra @ 50kW, 6weeks (Cont’d)
K+K0 missing mass (2KL)
# of K-K-pp = 776
ppK-K- rate = 1x10-4
beam power : 50kW, 6weeksproduction rate:• K-K-pp bound-state = parameter• (3N) K-K-LL phase-space = 5x10-5 (fix)• (3N) K+K0S0S0p0 phase-space = 5x10-5 (fix)• (2N) K+K0K0S0(n) phase-space = 3x10-4 (fix)
# of K-K-pp = 389
K+K0 missing mass (2KL)
ppK-K- rate = 0.5x10-4
The in-flight K+K0 missing mass spectrum looks nice, however, the backgrounds and the K-K-pp signal are unified in case the K-K-pp production yield is less than ~ 0.5x10-4!
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51
Expected Spectra @ 50kW, 6weeks
K+K0LL missing-mass2 (2K2L)
1GeV/c pbar
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52
Other backups
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53
Double-Strangeness Production Yieldby Stopped-pbar Annihilation
From several stopped-pbar experiments, the inclusive production yields are:
Naively, the double-strangeness production yield would be considered as:
g : reduction factor ~ 10-2
2( ) ~ 5 10R pp KK - 3 0 2
4 0 2
( ( )) ~ 0.6 10
( ( )) ~ 1.1 10
R p He
R p He
-
-
L S
L S
2 5
( )
( ) ~ 10
R pA KKKK
R pp KK g -
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54
Interpretation of the Experimental ResultsAlthough observed statistics are very small, the results have indicated a high yield of ~10-4, which is naively estimated to be ~10-5.
Possible candidates of the double-strangeness production mechanism are:rescattering cascades, exotic B>0 annihilation (multi-nucleon annihilation)
formation of a cold QGP, deeply-bound kaonic nuclei,H-particle, and so on
single-nucleonannihilation
rescatteringcascades
multi-nucleonannihilation
B=0 B>0B>0
the mechanism is NOT known well
because of low statistics
of the experimental results!
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55
K+K0LL Final State & Background3 0
0
p He K K X
K K
L LThis exclusive channel study is equivalent tothe unbound (excited) H-dibaryon search!
Q-value X momentum LL mass L-L angle
K-K-pp very small ~ at rest MLL > 2ML back to back
H-dibaryon large boosted MLL ~ 2ML ~ 0
Possible background channelsdirect K+K0LL production channels, like:
S0gL contaminations, like:
3 0
3 0 0 ...
p He K K
p He K K p
L L
L L
3 0 0
0
p He K K
K K g
L S
L L
be eliminated by the kinematical constraint,
ideally
be distinguished by inv.-mass only major background source
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56
Expected Kinematics (Cont’d)3 0p He K K L L
MH = 2ML
3 0p He K K H
L momentum LL inv. massLL spectra
L-L opening-angle
strong correlation of LL opening-angle in K-K-pp/H productions
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57
Detector DesignKey pointslow material detector systemwide acceptance with pID E15 CDS @ K1.8BR
CDCType A A’ A U U’ V V’ A A’ U U’ V V’ A A’
Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
radius 190.5 204.0 217.5 248.5 262.0 293.0 306.5 337.5 351.0 382.0 395.5 426.5 440.0 471.0 484.5
ZTPCLayer 1 2 3 4
radius 92.5 97.5 102.5 107.5
B = 0.5TCDC resolution : srf = 0.2mm
sz’s depend on the tilt angles (~3mm)ZTPC resolution : sz = 1mm
srf is not used for present setup
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58
Expected Spectra @ 50kW, 6weeks
K+K0LL missing-mass2 (2K2L)
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with Dipole-setup @ K1.1
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60
Detector Design (Cont’d)new dipole setup @ K1.1
CDCType A A’ A U U’ V V’ A A’ U U’ V V’ A A’
Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
radius 500 525 550 575 600 625 650 675 700 725 750 775 800 825 850
INC (wire chamber)Type A A’ A U U’ V V’ A A’ A U U’ V V’ A A’ A
Layer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
radius 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420
The design goal is to become the common setup for the f-nuclei experiment with in-flight pbar-beamB = 0.5TDouble Cylindrical-Drift-Chamber setuppID is performed with dE/dx measurement by the INC
INC resolution : srf = 0.2mm , sz = 2mm (UV)CDC resolution : srf = 0.2mm, sz = 2mm (UV)CDC is NOT used for the stopped-pbar experiment
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61
Detector Acceptance
dipole @ K1.1--- LL detection--- K0
SK+ w/ L-tag detection--- K0
SK+LL detection
Pbar+3He K++K0S+K-K-pp,
K-K-pp LL,G(K-K-pp)=100MeV
binding energy
B.E.=120MeV B.E.=150MeV B.E.=200MeV0.00
0.05
0.10
acce
ptan
ce
stopped1GeV/c
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62
Expected Spectra @ 50kW, 6weeks
62
# of K-K-ppLL = 138
LL invariant mass (2L) LL invariant mass (2K2L)
# of K-K-ppLL = 14
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 327 # of K-K-pp = 46
stopped pbar
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63
Expected Spectra @ 50kW, 6weeks
stopped pbar
K+K0LL missing-mass2 (2K2L)
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64
Expected Spectra @ 50kW, 6weeks
64
# of K-K-ppLL = 554
LL invariant mass (2L) LL invariant mass (2K2L)# of K-K-ppLL = 38
K+K0 missing mass (2K) K+K0 missing mass (2K2L)
# of K-K-pp = 1473 # of K-K-pp = 82
1GeV/c pbar
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65
Expected Spectra @ 50kW, 6weeks
1GeV/c pbar
K+K0LL missing-mass2 (2K2L)
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Past Experiments of Stopped-pbar Annihilation
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pbar+3He charged particle multiplicity at restCERN LEAR, streamer chamber exp.NP A518, 683 (1990).
nc1 5.14 +- 0.403 39.38 +- 0.885 48.22 +- 0.917 7.06 +- 0.469 0.19 +- 0.08
<nc> 4.155 +- 0.06
branch(%)
charged particle multiplicity at restform Rivista Del Nuovo Cimento 17, 1 (1994).
pbar+4He charged particle multiplicity at restCERN LEAR, streamer chamber exp.NP A465, 714 (1987).[data in nuovo- ciment is listed below, which is a higher statistics than NPA465]
nc1 3.36 +- 0.352 5.03 +- 0.423 33.48 +- 0.924 12.26 +- 0.635 35.68 +- 0.936 3.51 +- 0.367 6.24 +- 0.478 0.19 +- 0.089 0.24 +- 0.10
<nc> 4.097 +- 0.07
branch(%)
CERN LEAR streamer chamber exp.NIM A234, 30 (1985).
70.4 2.5%
29.6 2.5%
0.42 0.05
a
a
a a
pp
pn
pn pp
s
s
s s
They obtained
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KKbar production-rate for pbar+p at restform Rivista Del Nuovo Cimento 17, 1 (1994).
the KKbar production-rate R for pbar+p annihilation at rest(obtained from hydrogen bubble chamber data)
0 0
0 0
0 0 0 0 0
0 0 0 0
1.733 0.067%
1.912 0.141%
1.701 0.082%
3 1 2.149 0.065%4 25.35 0.18%
S
R K K
R K K
R K K R K K
R K R K K R K K R K K
R KK R K K R K K R K K R K K
-
-
-
- -
There is a great deal of data on the production of strange particles on 1H and 2H but only few ones on heavier nuclei.
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L/K0s production-rate and multiplicity for pbar+A at rest
form Rivista Del Nuovo Cimento 17, 1 (1994).
charge multiplicities decrease by ~1 when L/K0S is produced
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DIANA [Phys.Lett., B464, 323 (1999).]pbarXe annihilationp=<1GeV/c pbar-beam @ ITEP 10GeV-PS700-liter Xenon bubble chamber, w/o B-field106 pictures 7.8x105 pbarXe inelastic 2.8x105 pbarXe @ 0-0.4GeV/cpbarXeK+K+X : 4 events (0.31+/-0.16)x10-4
pbarXeK+K0LX : 3 events (2.1+/-1.2)x10-4
4 events 3 events
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interpretation of the DIANA result (pbarXe)from J.Cugnon et al., NP, A587, 596 (1995).
The observed double strangeness yield is explained by conventional processes described by the intranuclear cascade model, as listed in the following tables.
They also show the B=2 annihilations, described with the help of the statistical model, are largely able to account for the observed yield: i.e., the branching ratio of the LLKK state in pbar-NNN annihilation is equal to ~10-4 at rest (B=1 annihilations are not so helpful).
However they claim the frequency of even B=1 annihilation is of the order of 3-5% at the most [J.Cugnon et al., NP, A517, 533 (1990).] (is it common knowledge ?), so they conclude it would be doubtful to attempt a fit of the data with a mixture of B=0 and 2 annihilations.
On the other hand, the Crystal Barrel collaboration @ CERN/LEAR concludes their pbardLK0/S0K0 measurements disagree strongly with conventional two-step model predictions and support the statistical (fireball) model.
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experimental values are not final values of the DIANA data
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Crystal Barrel (’86~’96) [Phys. Lett., B469, 276 (1999).]pbar4He annihilationstopped pbar @ CERN/LEARliquid deuteron targetcylindrical spectrometer w/ B-fieldSVX, CDC, CsI crystals~106 events of 2/4-prong with topological triggers
0 6
0 0 6
5
( ) (2.35 0.45) 10
( ) (2.15 0.45) 10
( ) (1.3 1.0) 10
Br pd K
Br pd K
Br pd pp
-
-
- -
L
S
support the statistical model
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OBELIX (’86~’96) [Nucl. Phys., A797, 109 (2007).]pbar4He annihilationstopped pbar @ CERN/LEARgas target (4He@NTP, H2@3atm)cylindrical spectrometer w/ B-fieldspiral projection chamber, scintillator barrels, jet-drift chambers238,746/47,299 events of 4/5-prong in 4Hepmin = 100/150/300MeV/c for p/K/p
4
( )
( )
( )
( )
s s
p He
K K p K K nnp
K K n K K nnn
K K n K K p nn
K K K nn K K K p nn
p p
p p p p
p p
p
- - - -
- - - -
- - -
- - -
S S
S S
S L
L
34+/-8 events (0.17+/-0.04)x10-4
4-prong
5-prong
5-prong
5-prong
* (xx) is not observed
4+/-2 events (0.28+/-0.14)x10-4
36+/-6 events (2.71+/-0.47)x10-4
16+/-4 events (1.21+/-0.29)x10-4
they discuss the possibility of formation and decay of K-K-nn and K-K-pnn bound system
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Introduction
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we will open new door to the high density matter physics, like the inside of neutron stars
Kaonic Nuclear Cluster (KNC)
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the existence of deeply-bound kaonic nuclear cluster is predicted from strongly attractive KbarN interaction
Kaonic Nuclei
BindingEnergy[MeV]
Width[MeV]
CentralDensity
K-p 27 40 3.5r0
K-pp 48 61 3.1r0
K-ppp 97 13 9.2r0
K-ppn 118 21 8.8r0
T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004).
the density of kaonic nuclei is predicted to be extreme high density
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Method Binding Energy (MeV) Width (MeV)
Akaishi, YamazakiPLB533, 70 (2002). ATMS 48 61
Shevchenko, Gal, MaresPRL98, 082301 (2007). Faddeev 55-70 90-110
Ikeda, SatoPRC76, 035203 (2007). Faddeev 79 74
Dote, Hyodo, WeiseNPA804,197(2008). chiral SU(3) 19+/-3 40-70 (pSN-decay)
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Theoretical Situation of KNCtheoretical predictions for kaonic nuclei, e.g., K-pp
Koike, HaradaPLB652, 262 (2007).DWIA
•whether the binding energy is deep or shallow•how broad is the width ?
3He(K-,n)
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no “narrow” structurePLB 659:107,2008
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Experimental Situation of KNC
4He( stopped K-,p)E549@KEK-PS
12C(K-,n)
12C(K-,p)
missing mass
E548@KEK-PS
Prog.Theor.Phys.118:181-186,2007.
arXiv:0711.4943
unknown strength between Q.F. & 2N abs.
deep K-nucleus potential of ~200MeV
-
K-pnn?
K-pp/K-pnn?
K-pn/K-ppn?
4He( stopped K-,LN)E549@KEK-PS
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Experimental Situation of KNC (Cont’d)
FINUDA@DAFNE OBELIX@CERN-LEAR
We need conclusive evidencewith observation of formation and decay !
DISTO@SATUREN
L-p invariant mass
PRL, 94, 212303 (2005) NP, A789, 222 (2007)
peak structure signature of kaonic nuclei ?
K-pp?K-pp?
PRL,104,132502 (2010)
K-pp?
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Experimental Principle of J-PARC E15
search for K-pp bound state using 3He(K-,n) reaction
K- 3He Formation
exclusive measurement byMissing mass spectroscopy
andInvariant mass reconstruction
Decay
K-ppcluster
neutron
L p
pp-
Mode to decay charged particles
Missing
mass
Spectroscop
y
via neutron
Invariant
mass
reconstructio
n
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J-PARC E15 Setup
1GeV/cK- beam
p
p-p
n
NeutronToF Wall
CylindricalDetectorSystem
Beam SweepingMagnet
K1.8BR Beam Line
flight length = 15mneutron
Beam trajectory
CDS &target
SweepingMagnet
NeutronCounter
Beam LineSpectrometer
E15 will provide theconclusive evidence of K-pp