Double Anti-kaon Productionin Nuclei by Stopped Anti-proton

Annihilation

F.Sakuma, RIKEN

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International Workshop on ”Physics and Upgrade of the J-PARC Hadron Facility”(post Hyp-X workshop), Sep. 18-19, 2009

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This talk is based on the LoI submitted in June, 2009.

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Introduction of “Kaonic Nuclear Cluster”

Possibility of “Double-Kaonic Nuclear Cluster”

by Stopped-pbar AnnihilationExperimental ApproachSummary and Outlook

Contents of this talk

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Introductionof “Kaonic Nuclear Cluster”

Mass-less Quark

Higgs Mechanism

Chiral SymmetryBreaking

QGP neutronstar

SPS, RHIC, LHC

KEK-PSW.Weise NPA553, 59 (1993).

J-PARC?

The Origin of Mass

(quark effective massqq )

the missing piece is exploring hadron

properties in dense matter

most of the mass of matter are given by

Mu,d=0MeV

Mu,d~300MeV

Mu,d~3MeV

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Neutron Starhigh-density matter above

the nuclear density?

core material of neutron stars

Outer Crust

Inner Crust 0.3-0.5r0

Outer Core 0.5-2r0

Inner Core 2-15r0

possibility of the existence of a kaon condensed phase

--- the structure of neutron stars ---

r0=0.17fm-3

=2.8x1017kg m-3

the highest density matter in our familiar material is a nucleus

n~10-14m

p

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KN interaction

Y.Akaishi & T.Yamazaki, PLB535, 70 (2002).

The possibility of kaon condensation is supported by …

experimental results

theoretical investigationsvarious models predict kaon condensation (mean field theories, effective interaction theories, …)

Kaonic atom data indicates a strongly attractive KN interaction(KpX@KEK, DEAR@DAFNE)

this suggests“the existence of deeply-bound K−-nuclei states”

we will open new door to the condensed matter physics, like the inside of neutron stars

Kaonic Nuclear Cluster (KNC)

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if deeply-bound kaonic nuclear states exist …

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

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)

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

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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)

the situation is still controversial, because of no conclusive evidence yet!

peak structure signature of kaonic nuclei ?

K-pp?K-pp?

arXiv:0810.5182

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

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Possibility of “Double-KaonicNuclear 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).

p p K K K K

The elementary pbar-p annihilation reaction:

is forbidden for stopped pbar, because of a negative Q-value of 98MeV

Double-Strangeness Production with pbar

However, if multi kaonic nuclear exists with deep bound energy, following pbar annihilation reactions will 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

- -

- -

- -

- -

-

-

-

-

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theoreticalprediction

B.E.=117MeVG=35MeV

B.E.=221MeVG=37MeV

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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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Past Experiments of Double-Strangeness Production in Stopped-pbar Annihilation

Observations of the double-strangeness production in stopped pbar annihilation have been reported by only 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-Ln 16+/-4 1.21+/-0.29

K+K+K-Lnn 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

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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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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Experimental Approach

Anyway, the double-strangeness production yield of ~10-4 makes it possible to explore the exotic systems, if exist.

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How to Measure?

3 0p He K K K K pp - - In the following discussion, we limit the reaction:

(although K-K-pp decay modes are not known,)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- mode3 particles, and the other one is identified by missing mass

final state = K+K0LL

We needwide-acceptance

detectors.

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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 > 2xML back to back

H-dibaryon large boosted MLL ~ 2xML ~ 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

be distinguished by inv.-mass only major background source

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Expected Kinematicsassumptions:widths of K-K-pp/H = 0many-body decay = isotropic decay

3 0Sp He K K K K pp - -

B.E=109MeV B.E=150MeV B.E=200MeV(threshold)

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

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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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Beam-LineWe would like to perform the proposed experiment

at K1.1 or K1.8BR beam line

pbar stopping-rate

30GeV-9mA,6.0degreesNi-target

pbar production yield with a Sanford-Wang

1.3x103 stopped pbar/spill@ 0.65GeV/c, ldegrader~14cm

Incident Beammomentum bite : +/-2.5% (flat)incident beam distribution : ideal

DetectorsCarbon Degrader : 1.99*g/cm3

Plastic Scintillator : l=1cm, 1.032*g/cm3

Liquid He3 target : f7cm, l=12cm, 0.080*g/cm3

pbar stopping-rate evaluation by GEANT4

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Expected Double-Strangeness Yieldpbar beam momentum : 0.65GeV/cbeam intensity : 3.4x104/spill/3.5spbar stopping rate : 3.9%

9.6x104 double-strangeness/month

9.6x103 K+K0LL/monthbranching ratio to K+K0LL final state : 0.1

stopped-pbar yield : 1.3x103/spill/3.5s

Double-strangeness production : 1x10-4/stopped-pbar

a mere assumption!

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Detector Designdesign conceptlow material detector systemwide acceptance with pIDuseful for other experiments

E15 setup @ 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

We are considering2-types of detector

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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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Trigger Scheme

pbar3He charged particle multiplicity at restCERN LEAR, streamer chamber exp. NPA518,683 91990).

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 = 1.3x103/spill

All events with a scintillator hit can be accumulated

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Expected Signals

assumptions:widths of K-K0pp/H = 0B.E. of K-K-pp = 200MeVMH = 2xML

branching ratio to K+K0LL final state = 0.1DAQ & analysis efficiency = 0.7 6.7x103 K+K0LL/monthGenerated ratio K-K-pp:H:LL = 0.1:0.1:0.8KKppLL and HLL decay branches are assumed to be 100%S0gL contribution is NOT considered for the inclusive measurements

pbar+3HeK+K0S+ X (X=KKpp/H/LL) events are generated isotropically at the

center of the detector system# of generated events is 200k for each caseobtained yields are scaled by the estimated K+K0LL yieldchamber resolution, multiple scattering and energy losses are fully took into account using GEANT4 toolkitcharged particles are traced with spiral fit

LL invariant mass with (K+ or K0) reconstructionK+K0 missing mass with one more L reconstruction

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Expected Signals (Cont’d)

K+K0 miss-mass with E15 setup K+K0 miss-mass with NEW setup

sK-K-pp = 12MeVsH = 45MeV

sK-K-pp = 8MeVsH = 25MeV

LL inv-mass with NEW setup

sK-K-pp = 27MeVsH = 0.7MeV

24 K-K-pp events/month

19 K-K-pp events/month 27 K-K-pp events/month

LL inv-mass with E15 setup

sK-K-pp = 34MeVsH = 14MeV

25 K-K-pp events/month

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Summary and Outlook

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Summary

OutlookWe are investigating further realistic estimation of the K+K0LL yield and the backgrounds.

We are now preparing the proposal for J-PARC based on the LoI.

We propose to search for double strangeness production by pbar annihilation on helium nuclei at rest.

The proposed experiment will provide significant information on double strangeness production and double strangeness cluster states, like K-K-pp.

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Back-Up

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Decay Particle Momenta

K-K-pp (B.E.=200MeV)

H (MH=2*ML)

LL

K0-p+ K0-p-

L-p-L-p

E15 setup case

K0Sp+p- :206MeV/c at rest

Lpp- :101MeV/c at restbgct(K+) = 0.75m @100MeV/c

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Time Schedule

Year (JFY) K1.8BR K1.1 (fN)2009 beam-tune proposal2010 E17 R&D, design2011 E15 R&D, design2012 E15 construction2013 L(1405) 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/L(1405)?K1.1 : joint project with the fN experiment?