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) , and Phys. Rev. C 84 (2011) [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

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

expected K - K - pp cross-section The free  production CS in p+p collision is known to be   ~ 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   ~ x   ~ 50nb (= x 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

8-10GeV proton 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

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, g/cm 3 12 cm) ~10 4 / month K - K - pp 5

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 )]

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

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

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

J-PARC for example … e + e - acceptance K + K - acceptance E16 spectrometer + hadron-spectrometer with 10 8 ppp 10

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

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

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

acceptance calculation (Cont’d) detector acceptance (degree) K+K+ -- p double-  accepted (~0.7%) 14 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 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%

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

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

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

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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) 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 Experimental Situation of KNC  NE We need more evidences in various channels! PRL, 94, (2005) PRL,104, (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 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

8GeV decay 23