search for double-kaonic nuclear cluster (K-K-pp)using p+p reaction

F.Sakuma, RIKEN

discussion is based on •Proc. Jpn. Acad., Ser. B, 87 (2011) 362-370., and•Phys. Rev. C 84 (2011) 015207[M. Hassanvand, Y. Akaishi and T. Yamazaki]

10GeV 陽子陽子衝突における二重Ｋ中間子核の生成 --- 実験フィージビリティ ---

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experimental principle

8GeV

decay

the produced K-K-pp can be identified by bothmissing-mass spectrum M(K+K+)invariant-mass spectrum M()

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production

expected K-K-pp cross-section• The free production CS in p+p collision is known to be

~ 10-3 x total ~ 50b• The free * production CS at 2.83GeV is known to be

* ~4.5b ~ 0.1 x

• The double- production CS is expected to be ~ 0.001 x ~ 50nb (= 10-3 x 10-3 x total)

• Thus, the double-* production CS is expected to be ~ 0.01 x ~ 0.5nb

• The DISTO result indicates the K-pp production CS is as much as * production CS, so we simply assume K-K-pp production CS to beK-K-pp ~ ~ 0.5nb

Of course, these are very rough estimations Of course, these are very rough estimations and depend on incident energyand depend on incident energy 3

8-10GeV proton yield @ high-p

Prof. Noumi

If yield of proton is assume to be as same as that of pion,

~108 proton/spill(6s) is expected with pp~8-10GeV 4

production-yield estimation

• CS : K-K-pp ~ 0.5nb• Beam : 8 GeV proton 108 / 6s x 1 month (30d) = 4x1013

• Target : LH2 target 0.85 g/cm2

(= SKS target, 0.0708 g/cm3 12 cm)

~104 / month K-K-pp5

kinematics

[momentum vs. cos(lab)]

p(K+2) vs. p(K+

1)

cos(lab)(K+2) vs.

cos(lab)(K+1)

cos(lab)(2) vs.cos(lab)(1)

p(2) vs. p(1)

production & decays are assumed to be isotropic

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B.E = 200MeV

K+

[momentum vs. cos(lab)]

kinematics (Cont’d)- from

[momentum vs. cos(lab)]

p from [momentum vs. cos(lab)]

cos(lab)(p) vs.cos(lab)() p(p) vs. p(-)

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B.E = 200MeV

requirements for detector• wide-coverage forward-

detector in order to detect double-K+ and double- (0-60 degrees)

• good kaon separation in trigger level (pK<~4GeV/c)

• high-resolution and high-rate detector

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n=1.008

n=1.026

KEK-PS E248 (AIDA)Past Experiment …Past Experiment …

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12GeV p+p K++K++X

experiment @ J-PARCfor example …

+15

-15

+15

-15+45 -45

e+e- acceptance

K+K- acceptance

E16 spectrometer + hadron-spectrometerwith 108 ppp

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acceptance calculation• As a first step, acceptance without magnetic

field is evaluated.• Angular distribution at the generated point is

used.

+15

-15

+15

-15+45 -45

e+e- acceptance

K+K- acceptance11

acceptance calculation (Cont’d)

detectoracceptance

(degree)

(deg

ree)

K+

- p

generated events

Acceptance will enlarge in horizontal direction if magnetic field is applied?

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B.E = 200MeV

acceptance calculation (Cont’d)

detectoracceptance

(degree)

(deg

ree)

K+

- p

double-K+ accepted (~16%)

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B.E = 200MeV

acceptance calculation (Cont’d)

detectoracceptance

(degree)

(deg

ree)

K+

- p

double- accepted (~0.7%)

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B.E = 200MeV

summary of acceptance calculation

acceptance for the exclusive measurement is 0.0%with this experimental setup w/o magnetic field

double-K+ accepted event double- accepted event

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acceptance = 16% 1600 / month acceptance = 0.7% 30 / month

K+

[mom vs. cos(lab)]

- from [mom vs. cos(lab)]

p from [mom vs. cos(lab)]

K+

[mom vs. cos(lab)]

- from [mom vs. cos(lab)]

p from [mom vs. cos(lab)]

decay :100% pp-- decay: 40%

Kaon identification

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n=1.02

K+

[mom vs. cos(lab)]

however, proton contamination is … ???

experiment @ J-PARCother choice?

New proposed spectrometer with 108 ppp

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kaon identification in trigger levelHigh resolutionHigh detection rate

anyway …

are elemental requirements.

from the Construction Proposal

summary• Feasibility of search for double kaonic-nuclear-cluster, K-K-pp,

using 8-10 GeV proton beam is discussed.• Experimental principle is:– 8GeV p+p K++K++X K++K+++– missing mass of K+K+ and/or invariant mass of

• Requirements for detectors are:– wide-coverage forward-detector (0-60 degrees)– good kaon separation in trigger level (pK<~4GeV/c)– high-resolution and high-rate detector

• With the upgraded E16 spectrometer, if double-K+ trigger is realized in momentum region < 4 GeV/c then inclusive K+K+ measurement could be possible.

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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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T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004).

Density [1/fm3]

the density of the KNC is predicted to be high high densitydensity more than normal nuclear-density (0)

KKbarbarN interaction N interaction is clarified to be strongly attractive strongly attractive by Kaonic-atom experiments in 20th.

This leads the prediction of deeply-bound kaonic deeply-bound kaonic nuclear cluster (KNC)nuclear cluster (KNC), as many theorists pointed out.

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Experimental Situation of KNC

FINUDA@DANE

We need more evidences in various channels!

DISTO@SATURENPRL, 94, 212303 (2005) PRL,104,132502 (2010)

stopped-K- + A ( + p) + X 2.85GeV-p + p ( + p) + K+

B.E. = 115MeV = 67MeV

B.E. = 103MeV = 118MeV

Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…

KK--ppppp?p?KK--ppppp?p?

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Double-Kaonic Nuclear Cluster (DKNC)The double-kaonic nuclear clusters have been predicted theoretically.

How to produce the double-kaonic nuclear cluster?heavy ion collision(K-,K+) reactionpbarA annihilation

another choice, p+p collision

PL,B587,167 (2004).

The double-kaonic clusters have much stronger binding energy and a much higher density than single ones.(AMD calc.)

ppn

ppnK-

ppnK-K-

J-PARC LoI

8GeVdecay

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