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

1. 10GeV陽子陽子衝突における二重Ｋ中間子核の生成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 --- search for double-kaonic nuclear cluster (K-K-pp)using p+p reaction • 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] F.Sakuma, RIKEN

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

3. expected K-K-pp cross-section • The free L production CS in p+p collision is known to be sL ~ 10-3 x stotal ~ 50mb • The free L* production CS at 2.83GeV is known to be sL* ~4.5mb ~ 0.1 x sL • The double-L production CS is expected to be sL+L~ 0.001 x sL~ 50nb (= 10-3x 10-3 x stotal) • Thus, the double-L* production CS is expected to be sL*+L*~ 0.01 x sL+L~ 0.5nb • The DISTO result indicates the K-pp production CS is as much as L* production CS, so we simply assume K-K-pp production CS to be sK-K-pp ~sL*+L* ~ 0.5nb Of course, these are very rough estimations and depend on incident energy

4. 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

5. production-yield estimation • CS : sK-K-pp ~ 0.5nb • Beam : 8 GeV proton 108 / 6s x 1 month (30d) = 4x1013 • Target : LH2target 0.85 g/cm2 (= SKS target, 0.0708 g/cm3 12 cm) ~104 / month K-K-pp

6. kinematics B.E = 200MeV K+ [momentum vs. cos(qlab)] production & decays are assumed to be isotropic p(K+2) vs. p(K+1) cos(qlab)(K+2) vs. cos(qlab)(K+1) L [momentum vs. cos(qlab)] p(L2) vs. p(L1) cos(qlab)(L2) vs. cos(qlab)(L1)

7. kinematics (Cont’d) B.E = 200MeV p- from L [momentum vs. cos(qlab)] cos(qlab)(p) vs. cos(qlab)(p-) p(p) vs. p(p-) p from L [momentum vs. cos(qlab)]

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

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

10. experiment @ J-PARC for example … +15 E16 spectrometer + hadron-spectrometer -15 with 108 ppp -45 +45 +15 -15 e+e- acceptance K+K- acceptance

11. acceptance calculation +15 • As a first step, acceptance without magnetic field is evaluated. • Angular distribution at the generated point is used. -15 -45 +45 +15 -15 e+e- acceptance K+K- acceptance

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

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

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

15. summary of acceptance calculation double-K+ accepted event double-L accepted event acceptance = 16%  1600 / month acceptance = 0.7%  30 / month • LL decay :100% • ppp-p- decay: 40% K+ [mom vs. cos(qlab)] K+ [mom vs. cos(qlab)] p- from L [mom vs. cos(qlab)] p from L [mom vs. cos(qlab)] p- from L [mom vs. cos(qlab)] p from L [mom vs. cos(qlab)] acceptance for the exclusive measurement is 0.0% with this experimental setup w/o magnetic field

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

17. experiment @ J-PARC other choice? New proposed spectrometer with 108 ppp from the Construction Proposal anyway … • kaon identification in trigger level • High resolution • High detection rate are elemental requirements.

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++L+L • missing mass of K+K+ and/or invariant mass of LL • 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.

20. Kaonic Nuclear Cluster (KNC) • KbarN interaction is clarified to be strongly attractive by Kaonic-atom experiments in 20th. • This leads the prediction of deeply-bound kaonic nuclear cluster (KNC), as many theorists pointed out. the density of the KNC is predicted to be high density more than normal nuclear-density (r0) Density [1/fm3] T.Yamazaki, A.Dote, Y.Akiaishi, PLB587, 167 (2004). we will open new door to the high density matter physics, like the inside of neutron stars

21. Experimental Situation of KNC B.E. = 103MeV G = 118MeV B.E. = 115MeV G = 67MeV K-ppLp? K-ppLp? FINUDA@DAFNE DISTO@SATUREN PRL, 94, 212303 (2005) PRL,104,132502 (2010) stopped-K- + A  (L + p) + X 2.85GeV-p + p  (L + p) + K+ We need more evidences in various channels! Because there is a discrepancy between THEORETICAL PREDICTIONS and EXPERIMENTAL OBSERVATIONS…

22. Double-Kaonic Nuclear Cluster (DKNC) The double-kaonic nuclear clusters have been predicted theoretically. ppn The double-kaonic clusters have much stronger binding energy and a much higher density than single ones. (AMD calc.) ppnK- PL,B587,167 (2004). • How to produce the double-kaonic nuclear cluster? • heavy ion collision • (K-,K+) reaction • pbarA annihilation ppnK-K- J-PARC LoI another choice, p+p collision

23. 8GeV decay