EXOTIC ATOMSNUCLEI T Yamazaki RIKEN Yukawa mesons 1935

EXOTIC ATOMS/NUCLEI T. Yamazaki, RIKEN • • Yukawa mesons (1935) Anderson PR 51(1937), Nishina PR 52(1937): muon Tomonaga-Araki, PR 58(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)

Exotic Resonance States of Antiprotons, Pions and Kaons in Atomic and Nuclear Systems Toshimitsu 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 Xembedded in continuum Exotic atoms/nuclei Negative pions Negative kaons Antiprotons

Hadron-Nucleus Bound-State Spectroscopy Toshimitsu 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

Deeply Bound Pionic States 1 s pionic states in heavy (N>Z) nuclei • Shallow pionic atoms: • Last orbital: • Deeply bound states: ~1 -10 ke. V ~ 0. 5 Me. V ~ 5 Me. V 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, 3 He) at GSI

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

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

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

in 205 Pb

Sn(d, 3 He) spectra K. Suzuki et al. , PRL (2003)

PIONIC NUCLEI as a unique indicator of Chiral Symmetry Restoration in the nuclear medium Fundamental building blocks: • Nuclei: protons (938 Me. V) + neutrons (940 Me. V) + virtual mesons (pion: 140 Me. V; etc. ) • Hadrons: quarks + gluons: u (~ 5 Me. V), d (~ 8 Me. V), s (~ 150 Me. V) 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 b 1(free) /b 1*(r) -->>

B 1 s and 1 s in Sn Isotopes

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

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

Hadron Bound States

Nuclear excited states with strangeness S = -1 as Feshbach resonances ���� p����� , n(940) ������ : stable Hypernuclei: Many observed S������� , S � ������ S Hypernuclei: Unstable: S conversion Exception: 4 SHe �� 405� : K-p bound state K-N(1433) K- nuclear bound states?

Akaishi KN Potential Y. Akaishi and TY, PRC (2002)

Diagram Kaon Bound System

pp. K- bound system - kaonic hydrogen nuclear molecule

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

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

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

Very exotic systems kaonic tri-protons kaonic tetra-protons

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

(K, ) and ( , K) reactions for various K- bound systems * Large q: good for large internal momentum * Varieties (K-, -) ( -, K 0) ( +, K+) DQ -1 0 target p L L* S +, S +* [n] L L* d pn. Kpp. K 3 He ppn. Kppp. K 4 He ppnn. Kpppn. K- ( �, K 0) +1 S +, S +* pppp. K-

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

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

K Compound Nuclei • 1520 + p + n +…. ---> K- + p + n +… • ---> K- bound state +

Predicted (K-, -) Spectra Y. Akaishi

How about pp. K K , ppn. K K ? ?

Double kaonic nucleus // ppn. K-K- // 4 fm Density [fm-3] 0. 00 0. 07 4 fm 0. 14 Density [fm-3] 0. 00 0. 75 4 fm 1. 50 Density [fm-3] 0. 0 1. 5 3. 0 ppn. K-K- total B. E. = 6. 0 Me. V central density = 0. 14 fm-3 rms. R= 1. 59 fm total B. E. = 118 Me. V central density = 1. 50 fm-3 rms. R= 0. 72 fm total B. E. = 221 Me. V central density = 3. 01 fm-3 rms. R= 0. 69 fm

Kaonic Nuclei - Future Scope Very strong K--p attraction • • • Very deep discrete states: predicted BK ~ 100 Me. V 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

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

Spectroscopy ** Entrance channel spectroscopy Direct reactions: A+a --> X + b Missing-mass spectroscopy ** Decay channel spectroscopy Compound reactions --> X + anything X --> x 1 + x 2 + … Invariant-mass spectroscopy: Minv 2 = (E 1 + E 2 +. . )2 - (P 1 + P 2 +. . )2

Search for K- cluster fragments in HI reactions high-density environment provided by HI fireball Invariant mass spectroscopy for their decays K-pp --> L + p, K-ppn --> L + d

Kbar cluster decay in the freeze-out phase t. K (=10 fm/c) > tfreeze-out

FOPI from Kusche (Ph. D) 1999

FOPI from Kusche (Ph. D) 1999

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 pp. K- ---> + p ppn. K- ---> + d