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EXOTIC ATOMS/NUCLEI T. Yamazaki, RIKEN

EXOTIC ATOMS/NUCLEI T. Yamazaki, RIKEN. Yukawa mesons (1935) Anderson PR51(1937), Nishina PR52(1937): muon Tomonaga-Araki, PR58(1940): mesonic atom formation Fermi-Teller (1947) Strong-interaction shifts of pion: Jenkins et al. (1966)

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EXOTIC ATOMS/NUCLEI T. Yamazaki, RIKEN

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  1. EXOTIC ATOMS/NUCLEIT. Yamazaki, RIKEN • Yukawa mesons (1935) • Anderson PR51(1937), Nishina PR52(1937): muon • Tomonaga-Araki, PR58(1940): mesonic atom formation • Fermi-Teller (1947) • Strong-interaction shifts of pion: Jenkins et al. (1966) • Ericson-Ericson (1966), Tomozawa-Weinberg (1966) • Deeply bound pions: Toki-Yamazaki (1988) • First observation (1996)

  2. Exotic Resonance States of Antiprotons, Pions and Kaons in Atomic and Nuclear SystemsToshimitsu Yamazaki, RIKEN • Hadronic systems --> strong nuclear absorption --> short-lived, no discrete states • Exceptions: long-lived, discrete states in continuum: Energy spacing >Width • --> High-precision spectroscopy • Feshbach resonances: Bound states of X- embedded in continuum Exotic atoms/nuclei Negative pions Negative kaons Antiprotons

  3. Hadron-Nucleus Bound-State SpectroscopyToshimitsu Yamazaki (RIKEN) • Explore Chiral Symmetry Restoration in Nuclear Media Brown-Rho scaling: • HOW TO MEASURE In-medium hadron masses and interactions in well defined states and densities?? • POPULAR METHODS: Invariant-mass spectroscopy for decay particles in continuum medium • NEW METHOD: Bound-state spectroscopy: IF hadron bound states exist with narrow widths? How? Suppression mechanisms for nuclear absorption? Pionic Nuclei (1988 -): observed (1996,1998,2001), matured Kaonic Nuclei (2000 -): predicted, no observation yet

  4. Deeply Bound Pionic States1s pionic states in heavy (N>Z) nuclei • Shallow pionic atoms: • Last orbital:~1-10 keV • Deeply bound states: ~ 0.5 MeV ~ 5 MeV Still discrete states!! Coulomb attraction + Strong Interaction Repulsion ----->> Halo like pionic states (absorption suppressed) E. Friedman and G. Soff (1985) H. Toki et al. (1988): --->> pion transfer reactions First success: (d, 3He) at GSI

  5. From outside to inside * atomic states of X radiative transitions from outer orbitals * terminated cascade From inside to outside * nuclear resonance states * still bound states of X New Frontiers of Exotic Atoms/Nuclei EXOTIC ATOMS/NUCLEI

  6. s-wave p-wave Light 1s states in symmetric nuclei Seki-Masutani relation Double-scattering effect Pion-Nucleus Potential Parameters

  7. Overlapping density: maximum at The density-dependent potential parameter: is transposed to Pionic Bound States Probe Nuclear Surface

  8. in205Pb

  9. Sn(d,3He) spectraK. Suzuki et al., PRL (2003)

  10. PIONIC NUCLEIas a unique indicator ofChiral Symmetry Restorationin the nuclear medium Fundamental building blocks: • Nuclei: protons (938 MeV) + neutrons (940 MeV) + virtual mesons (pion: 140 MeV; etc.) • Hadrons: quarks + gluons: u (~ 5 MeV), d (~ 8 MeV), s (~ 150 MeV) Surprising discrepancies -->> ascribed to quark condensate in QCD vacuum: order parameter of chiral symmetry breaking QCD vacuum is subject to change: partial restoration of chiral symmetry HOW to prove or disprove this scenario? As in superconductors Pion decay constant in medium ---> Isovector pion-N interaction b1(free) /b1*(r) -->>

  11. B1s and 1s in Sn Isotopes

  12. Isovector s-wave interaction --->> pion decay constant in the medium Weise (2000, 2001) Kienle and TY (2001) Best probe: Pionic 1s in heavy nuclei GSI experiment on pionic 115Sn, 119Sn, 123Sn K. Suzuki et al. (2002) Pionic Bound States as an Indicator of Chiral Symmetry Restoration

  13. Evidence for partial restoration of chiral symmetry in nuclear medium probed by 1s pionic nuclei (2003) Isovector s-wave pN scattering length isoisoso

  14. Hadron Bound States

  15. Nuclear excited states with strangeness S = -1as Feshbach resonances p, n(940) L: stable LHypernuclei: Many observed S,S,S SHypernuclei: Unstable: SLconversion Exception: 4SHe L405: K-p bound state K-N(1433) K- nuclear bound states?

  16. Akaishi KN PotentialY. Akaishi and TY, PRC (2002)

  17. Diagram Kaon Bound System

  18. ppK- bound system - kaonic hydrogen nuclear molecule

  19. Y. Akaishi and TY, PRC (2002) TY and Y. Akaishi, PLB (2002) K- potentials and bound states

  20. Shrinkage effect:Competition between K-p attraction and nuclear incompressibility

  21. Antisymmetric Molecular Dynamics Method Isovector Deformation Dote et al. 3He --->3HeK-shrinkage !!

  22. Very exotic systemskaonic tri-protonskaonic tetra-protons

  23. Kaonic Be-8: Contracted Alpha Cluster Dote et al. (2002)

  24. (K,p) and (p,K) reactions for various K- bound systems * Large q: good for large internal momentum * Varieties (K-,p-) (p-,K0) (p+,K+) (p,K0) DQ -1 0 +1 target p LL* S+, S+* [n] - LL* S+, S+* d pnK-ppK- - 3He ppnK-pppK- - 4He ppnnK-pppnK-ppppK-

  25. Experimental SearchM. Iwasaki et al., at KEK 4He (stopped K-, n)K-3He

  26. L-doorway and L-compound mechanismsT. Yamazaki and Y. Akaishi, PLB 535 (2002) 70 Hepp et al., N.P. B 115 (1976) 82

  27. K- Compound Nuclei • 1520+ p + n +…. --->K- + p+ p + n +… • --->K- bound state + 

  28. Predicted (K-,-) SpectraY. Akaishi

  29. How about ppK-K-, ppnK-K- ??

  30. Double kaonic nucleus // ppnK-K- // 4 fm 4 fm 4 fm Density [fm-3] 0.00 0.07 0.14 Density [fm-3] 0.00 0.75 1.50 Density [fm-3] 0.0 1.5 3.0 ppn ppnK- ppnK-K- total B.E. = 118 MeV central density = 1.50 fm-3 rmsR= 0.72 fm total B.E. = 6.0 MeV central density = 0.14 fm-3 rmsR= 1.59 fm total B.E. = 221 MeV central density = 3.01 fm-3 rmsR= 0.69 fm

  31. Very strong K--p attraction Very deep discrete states: predicted BK ~ 100 MeV Highly excited resonance states In-medium KN interactions modified? Dense nuclear systems formed Possibly, Quark-Gluon phase at T = 0 Kaon condensation; strange matter Nuclear dynamics under extreme conditions Kaonic Nuclei - Future Scope

  32. Strangeness at high nuclear densities The nuclear incompressibility isovercome by the Strong K- p attraction At high density K- matter [K- p] + [K- p] + …+ n +… may be more stable

  33. Spectroscopy ** Entrance channel spectroscopy Direct reactions: A+a --> X + b Missing-mass spectroscopy ** Decay channel spectroscopy Compoundreactions --> X + anything X --> x1 + x2 + … Invariant-mass spectroscopy: Minv2 = (E1 + E2 +..)2 - (P1 + P2 + ..)2

  34. Search for K- cluster fragments in HI reactionshigh-density environment provided by HI fireballInvariant mass spectroscopy for their decaysK-pp -->L + p, K-ppn -->L + d

  35. Kbar cluster decay in the freeze-out phasetK(=10 fm/c) > tfreeze-out

  36. FOPI from Kusche (PhD) 1999

  37. FOPI from Kusche (PhD) 1999

  38. Search for K- clusters as residues in heavy-ion reactions • High density medium accommodated in fire balls • Deep self-trapping centers in fire balls • Freeze-out phase • Invariant mass spectroscopy for fragments ppK- ---> L + p ppnK- ---> L + d

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