1. 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 --- 1

2. experimental principle 8GeV decay the produced K - K - pp can be identified by both missing-mass spectrum  M(K + K + ) invariant-mass spectrum M(  ) 2 production

3. expected K - K - pp cross-section The free  production CS in p+p collision is known to be   ~ 10 -3 x  total ~ 50  b The free  * production CS at 2.83GeV is known to be   * ~4.5  b ~ 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 be  K-K-pp ~   ~ 0.5nb Of course, these are very rough estimations and depend on incident energy 3

4. 8-10GeV proton yield @ high-p Prof. Noumi If yield of proton is assume to be as same as that of pion, ~10 8 proton/spill(6s) is expected with p p ~8-10GeV 4

5. production-yield estimation CS :  K-K-pp ~ 0.5nb Beam : 8 GeV proton 10 8 / 6s x 1 month (30d) = 4x10 13 Target : LH 2 target 0.85 g/cm 2 (= SKS target, 0.0708 g/cm 3 12 cm) ~10 4 / month K - K - pp 5

6. 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 6 B.E = 200MeV K + [momentum vs. cos(  lab )]

7. kinematics (Cont’d)  - from  [momentum vs. cos(  lab )] p from  [momentum vs. cos(  lab )] cos(  lab )(p) vs. cos(  lab )(   ) p(p) vs. p(  - ) 7 B.E = 200MeV

8. requirements for detector wide-coverage forward- detector in order to detect double-K + and double-  (0-60 degrees) good kaon separation in trigger level (p K <~4GeV/c) high-resolution and high- rate detector 8 n=1.008 n=1.026

9. KEK-PS E248 (AIDA) Past Experiment … 9 12GeV p+p  K + +K + +X

10. experiment @ J-PARC for example … +15 -15 +15 -15+45-45 e + e - acceptance K + K - acceptance E16 spectrometer + hadron-spectrometer with 10 8 ppp 10

11. 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 - acceptance 11

12. acceptance calculation (Cont’d) detector acceptance (degree) K+K+ -- p generated events Acceptance will enlarge in horizontal direction if magnetic field is applied? 12 B.E = 200MeV

13. acceptance calculation (Cont’d) detector acceptance (degree) K+K+ -- p double-K + accepted (~16%) 13 B.E = 200MeV

14. acceptance calculation (Cont’d) detector acceptance (degree) K+K+ -- p double-  accepted (~0.7%) 14 B.E = 200MeV

15. 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 15 acceptance = 16%  1600 / monthacceptance = 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%

16. Kaon identification 16 n=1.02 K + [mom vs. cos(  lab )] however, proton contamination is … ???

17. experiment @ J-PARC other choice? New proposed spectrometer with 10 8 ppp 17  kaon identification in trigger level  High resolution  High detection rate anyway … are elemental requirements. from the Construction Proposal

18. 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 (p K <~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. 18

19. 19

20. we will open new door to the high density matter physics, like the inside of neutron stars Kaonic Nuclear Cluster (KNC) 20 T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). Density [1/fm 3 ] high density the density of the KNC is predicted to be high density more than normal nuclear-density (  0 ) K bar N interaction strongly attractive K bar N interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20 th. deeply-bound kaonic nuclear cluster (KNC) This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out.

21. 21 Experimental Situation of KNC FINUDA@DA  NE We need more evidences in various channels! DISTO@SATUREN PRL, 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… K - pp   p?

22. 22 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 + ) reaction  p bar A 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

23. 8GeV decay 23