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F.Sakuma , RIKEN

Kaonic Nuclei. Possibility of double- kaonic nuclear cluster, “K - K - pp ”, search using p+p reaction @ high-p BL. F.Sakuma , RIKEN. Workshop on "Physics with General Purpose Spectrometer in the High-momentum Beam Line" 27-28 August 2018, Research Center for Nuclear Physics (RCNP).

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F.Sakuma , RIKEN

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  1. KaonicNuclei Possibility of double-kaonicnuclear cluster, “K-K-pp”, searchusing p+p reaction @ high-p BL F.Sakuma, RIKEN Workshop on "Physics with General Purpose Spectrometer in the High-momentum Beam Line" 27-28 August 2018, Research Center for Nuclear Physics (RCNP)

  2. Kaonic Nuclei • Bound states of nucleus and anti-kaon • Predicted as a consequence of attractive KbarN interaction in I=0 Meson properties change in nuclear media? Y.Akaishi & T.Yamazaki, PLB535, 70(2002). 1 2 3 0 • Will provide new insight on KbarN interaction in media

  3. High-Density Matter? Y.Akaishi and T.Yamazaki, PRC65(2002)044005. A. Dote et al. PRC70(2004)044313. etc. c.f. Nuclear Binding Energy a few MeV/nucelon @ A = 2,3 • Deep binding-energy  compact state? •  high density? • Narrow width Metastable  state?

  4. Present Status of KbarNN= “K-pp” KbarNN is symbolically notated as “K−pp” in this talk p-dK+X ppK+X stopped K- complicated reactions  “in-flight K-” induced reaction Phenomenological Chiral • Upper limits were also obtained: • LEPS@SPring8 [Inclusive d(g, K+p-)X] • HADES@GSI [Exclusive pppLK+]

  5. J-PARC E15 Experiment • 3He(in-flightK-,n) reaction @ 1.0 GeV/c • 2NA processes and Y decays can be discriminated kinematically

  6. “K-pp” Search @ K1.8BR

  7. Experimental Setup @ K1.8BR 15m

  8. 3He + K- L p n Selection E15 collab., arXiv:1805.12275 • Lp-p and p are detected with CDS • A missing neutron is identified by missing-mass of 3He(K-,Lp)n • Lpnmiss events are selected by log-likelihood method (lnL) • distance-of-closest-approach for each vertex • kinematical constraint

  9. IM(Lp) vs. Momentum Transfer qKn E15 collab., arXiv:1805.12275 IM(Lp) • Seems to consist of 3 components • Bound state • centroid NOT depend on qKn • Qasi-elastic K- abs. • centroid depends on qKn • Background • Broad distribution qKn=qLp

  10. IM(Lp) vs. Momentum Transfer qKn E15 collab., arXiv:1805.12275 IM(Lp) • Fit with 3 components • Bound state • centroid NOT depend on qKn • BW*(Gauss form-factor) • Qasi-elastic K- abs. • centroid depends on qKn • Followed by Lp conversion • Background • Broad distribution qKn=qLp * We conduct the fitting in each 2D bin

  11. “K-pp” Bound-State Select 0.35<qKn<0.65 GeV/c • BS and QF are well separated E15 collab., arXiv:1805.12275

  12. “K-pp” Bound-State Fit values that reproduce the spectrum: E15 collab., arXiv:1805.12275

  13. Present Status of “K-pp” p-dK+X ppK+X K-3HenX stopped K- Phenomenological Chiral • For further understandings: • L(1405) production  L*N doorway • pSNdecay channel  new info. of KbarNN

  14. In the E15 experiment, we have observed a very strong candidate of the “K-pp” bound-stateThen, how about two K-, “K-K-pp”? Present Status of “K-pp” p-dK+X ppK+X K-3HenX stopped K- Phenomenological Chiral • For further understandings: • L(1405) production  L*N doorway • pSNdecay channel  new info. of KbarNN

  15. Double-Kaonic Nuclear Cluster The double-kaonic nuclear clusters have been also predicted theoretically. ppn • much stronger binding energy • much higher density 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 @ K1.8BR another choice, p+p collision

  16. Experimental Principle 8GeV production decay • the produced K-K-pp can be identified: • missing-mass DM(K+K+) • invariant-mass M(LL) Exclusive measurement is desirable, as in case of “K-pp”

  17. “K-K-pp” Search @ high-p 2nd-target

  18. 8-10GeV Proton-Yield@ high-p 2nd-target Prof. Noumi If yield of proton is assume to be as same as that of pion, ~108proton/spill is expected with pp~8-10GeV

  19. Production-Yield Estimation • CS : sK-K-pp ~ 0.5nb (very “optimistic” assumption) • Beam : 8 GeV proton 108 / 6s x 1 month (30d) ~ 5x1013 • Target : LH2target 0.85 g/cm2( 0.0708 g/cm3 12 cm) K-K-pp ~ 104/ month

  20. Kinematics B.E = 200MeV K+ [momentum vs. cos(qlab)] All decay particles concentrate in forward region (~0.9<cosq) p- from L L [momentum vs. cos(qlab)] p from L

  21. Experimental Requirements • Forward tracking-system • ~0.9 < cosq • need high-rate detectors • Forward K-ID detector • ~1 < p < ~4GeV/c • p/K separation • Trigger-level selection OR Trigger-Less DAQ • Usage of n~1.008 aerogel? n~1.008

  22. with the E16-like Setup? E16 spectrometer + hadron-spectrometer +15 -15 with 108ppp -45 +45 +15 -15 e+e- acceptance K+K- acceptance

  23. Kinematics of Decay-Particles generated events K+ (degree) B.E = 200MeV detector acceptance (degree) p p-

  24. p(p,K+K+)X Acceptance double-K+ accepted (~16%) K+ (degree) B.E = 200MeV (degree) p p-

  25. p(p,LL)X Acceptance double-L accepted (~0.7%) K+ (degree) B.E = 200MeV (degree) p p-

  26. (Very Rough) Yield Estimation double-K+ accepted event double-L accepted event acceptance ~ 16%  ~ 1000 / mon acceptance ~ 0.7%  ~ 10 / mon • LL decay :100% K+ K+ [mom vs. cos(qlab)] p- from L [mom vs. cos(qlab)] p from L p- from L p from L [mom vs. cos(qlab)]  Hard to perform the exclusive measurement with the E16-like setup

  27. Would be feasible with the E50 Spectrometer Prof. Noumi RICH & Trigger-Less DAQ is essential!

  28. Summary • Strong candidate of “K-pp” has been observed in E15 • Existence of double kaonic-nuclear-cluster, “K-K-pp”, is also expected • “K-K-pp” search with 8-10 GeV proton beam is discussed. • 8GeV p+p K++K++”K-K-pp”  K++K++L+L • Exclusive measurement is desirable • Requirements for detectors are: • Forward tracking-system (~0.9<cosq) • Forward K-ID detector (~1<pK<~4 GeV/c) • With the E16-like setup, it seems to be difficult to perform the exclusive measurement  E50 spectrometer?

  29. 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

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

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

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