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M. Maggiora for DISTO collaboration, P. Kienle , K. Suzuki and T. Yamazaki

Evidence for a strongly bound K - pp populated in p + p -> K + + X reaction from DISTO data 1 st report on Sep 15,2008 at EXA08 somewhat preliminary, but Now FINAL at ECT*, Oct 15, 2009. M. Maggiora for DISTO collaboration, P. Kienle , K. Suzuki and T. Yamazaki. K - pp prediction.

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M. Maggiora for DISTO collaboration, P. Kienle , K. Suzuki and T. Yamazaki

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  1. Evidence for a strongly bound K-pppopulated in p + p -> K+ + X reaction from DISTO data1st report on Sep 15,2008 at EXA08somewhat preliminary, butNow FINAL at ECT*, Oct 15, 2009 M. Maggiora for DISTO collaboration, P. Kienle, K. Suzuki and T. Yamazaki

  2. K-pp prediction High nuclear density

  3. Extraordinary sticking of * + p into K-ppin pp collision predicted TY-YA PRC76, 2007** short collision length of pp ** compactness of K-pp** large momentum transfer If observed in p+p, it proves the compactness of K-pp

  4. pp -> K+L pkinematically complete

  5. DISTO @ Saturne: polarised proton beam up to T = 2.9 Gev Acceptance: Δφ = ± 15.5 Δθ = ± 45 • 2-cm thick unpolarised LH2 target • S170 magnet (< 14.7 KGauss, Δθ =  120 ,Δφ =  20) • semi-cylindrical 1mm-square scintillating fibers triplets inside magnet • MWPC planar triplets outside magnet • scintillator hodoscopes vertically and horizontally segmented • scintillator hodoscopes as polarimeter slabs • doped water Cerenkov counters

  6. Hyperon production: event reconstruction . Data set: refitted events with low χ2 χ2 requirement on the refit: most effective cut Mπp before refit ΔMpK after refit Hyperon production: event reconstruction Unrefitted M- p Reffitted MpK

  7. Purity of the gate selection >95% DISTO real data 140,000 events    p+p -> K+p MM(Kp) --> , 0 M 2Kvs M 2p (2.252= 5.06) (2.302= 5.29) 0 0 0

  8. Complicated detector efficiencyDeviation Spectrum Method UNC: Efficiency uncorrected raw data SIM: Simulation data of uniformly distributed events with efficiency correction and with the same cuts as applied to raw data DEV = UNC / SIMappliedbin by bin: Flat, if the data are subject to phase space only Peak, if the data involve an exotic component VALID method to find out an exotics, as far as the (L, p, K) is pure and kinematically complete. MM(K) = M(pL)

  9. Problem: how to distinguish between * ordinary: pp -> pL K+ * exotic: pp -> K+ X, X -> pL • Efficiency-corrected Dalitz plot x = M(pL)2y = M(KL)2

  10. forward peaked proton distribution Angular distributions of pL K+ important DYNAMICS but hidden in Dalitz plots Monoenergetic K+ in cm

  11. Proton angular distributionBest fit:with mB ~ 0.2 GeV

  12. No proton cut cosqK lab P(K) lab cosqK cm P(K) cm

  13. Various proton angle cuts  enhance the X peak Klab Kcm proton large angle proton small angle M(pL)2DM(K)2 cosqK cm Deviation projection spectra

  14. Robust nature of the peak any fake? Deviation spectra large-angle protons: high-ptforward protons: low-pt

  15. Background process Low- pt Akaishi Deviation spectrum always flat

  16. background process pp -> pKLcollision length = h/mBc, mB=mrxF Bump K + X Flat BG pKL mB~0.2 GeV

  17. Presence of a peak26s significanceM = 2.267 +- 0.002G = 0.118 +- 0.008with peakc2 /ndf = 34/24 = 1.4without peakc2 /ndf = 947/27 = 35overwhelmingly high statistical confidenceSymmetric shapeLp dominance

  18. disagree agree High nuclear density

  19. TY-YA_PRC76 (2007) 045201

  20. Conclusion 1. A robust peak observed in pp  K+ + p + L deviation spectra of both M(pL) and DM(K) 2. Presence of K-pp established with BK = 105 +- 2 MeV, G = 118 +- 5 MeV in agreement with the deep regime not with the shallow regime 3. Peak / continuum ~ 0.1; L1405 / L ~ 0.1 extraordinary sticking X / L1405 ~ 1, as predicted proving K-pp  strongly bound, dense system

  21. Implication of the even deeper binding New physics beyond: p-wave KbarN interaction Wycech Chiral symmetry restoration N-N short-range barrier diminished by K- uud – uud with intruding ubar Indicates possible presence of ultra deep K-NNN,,,,  FOPI M(dL) ~ 3140 MeV  T. Suzuki @KEK, S0, S+ ~ 3140 MeV

  22. Decay processes • G(Spp) ~ 40 MeV reduced because of the phase space reduction  <20 MeV • Non-pionic decays dominate T. Sekihara, D. Jido and Y. Kanada-En’yo: Phys. Rev. C79 (2009) 062201, G ~ G(Lp) + G(Sp) ~ 22 MeV • Gobs ~ 100 MeV: enhancement by higher density ? Symmetric shape at the Spp threshold Many theoretical questions

  23. Braun et al. K-d -> Lpp- FOPI 2008

  24. FOPI 2008 Braun et al. K-d -> Lpp-

  25. Now a new experiment performed at FOPI @ Tp = 3.1 GeVexpand the mass region beyond 2.4 GeV

  26. ＦＩＮＵＤＡ ＫＥＫ PerspectivesExperimental & theoretical studies encouraged** pp  KS0p** Dedicated pp experiment FOPI, HADESexpanded mass range** Dedicated 3He(K-,N) at J-PARC** Stopped K- KEK, FINUDA, AMADEUS** proton, HI reactions** Many theoretical problems

  27. Thank you very much

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