1. DPG, 11.03.08 Production of fragments with finite strangeness in heavy-ion collisions within a BUU+SMM combined model Th. Gaitanos, H. Lenske, U. Mosel Introduction Theoretical aspects Formation of relativistic hypernuclei in simulations Non-equlibrium transport dynamics (GiBUU) Fragmentation mechanism (coalescence, statistical approaches, e.g. SMM) Hybrid approach (GiBUU+SMM) Applications Benchmark: X+X@SIS/GSI, spectator fragmentation (ALADIN) X+X@2AGeV (HypHI), p+X@50GeV, X+X@20AGeV (J-PARC) Final remarks

2. DPG, 11.03.08 Introduction… Knowledge of YN & YY interaction (strangeness sector of hadronic EoS) ? important for physics of neutron stars strange „Hyperon Stars“, ~60% neutron, but ~20% occupation of protons and strange baryons (N.K. Glendenning, astro-ph/9707.351v1; F. Weber et. al., astro-ph/0705.2708v2) Formation of (exotic?) hypernuclei accessible in high-energy reactions (p+X, X+X) HypHI HypHI: 12 C( 6 Li)+ 12 C@SIS (in progress…) J-PARC J-PARC: p+ 12 C@50GeV, 12 C+ 12 C@20AGeV (in future…) PANDA PANDA: Antiproton-Nucleus (in future…) So far mainly from nuclear structure studies Info on properties of strange baryons in neutron rich matter needed  e.g. ( exotic) hypernuclei, e.g. 3 He Y, 5 He Y (Y=  )

3. Relativistic Hypernuclei…         Production of Hypernuclei in Relativistic HIC Production of many hyperons Secondary rescattering (  N  YK) Multiple coalescence of hyperons with fragments Theoretical Framework Phase-Space evolution Transport equations of Boltzmann type, e.g. Giessen-BUU model http://www.physik.uni-giessen.de/GiBUU/  http://www.physik.uni-giessen.de/GiBUU/ Description of fragment formation ? Statistical picture (SMM, A.Botvina & I.Mishustin), coalescence Description of hypernuclei formation? simple coalescence in coordinate (Y inside fragmenting source) and in momentum space

4. Dynamical aspects in X+X reactions (Spectators)… Spectators Well defined conditions after onset of instability… Anisotropy …and onset of equilibration Def. ofSpectators Y (0) >0.75 (ALADIN)+  <  sat /100

5. Benchmark: X+X reactions (spectator fragmentation in Au+Au@SIS)… Data: ALADIN-collaboration Reasonable description of spectator fragmentation

6. 12 C+ 12 C@2AGeV (HypHI)… Formation of hypernuclei from spectator fragmentation via coalescence (here only in coordinate space, e.g. condition: Y inside radius of fragmenting source) extremely low Note: extremely low total yields, e.g. orders of only view  b for light He-hypernuclei Consistent with previous studies: M.Wakai, NPA547(92)89c Very small systems  less compression  less pions available for rescattering inside spectators Very small systems  small interaction radius for pions passing through spectator

7. p+ 12 C@50GeV (J-PARC) – dynamical aspects… Two sources (residual target+moving source) Stable conditions after resonance decay Most of hyperons created & rescatter inside moving source

8. p+ 12 C@50GeV (J-PARC) – theor. estimations on hypernuclei… Hypernuclei: Simple coalescence (Y inside source‘s) Prediction: production of energetic hypernuclei (Similar results for 12 C+ 12 C@20AGeV)

9. DPG, 11.03.08 Final remarks & Outlook… Heavy-Ion Collissions  Fragmentation in spectator matter min. compression/expansion effects, almost no radial flow effects  Wide selection of experimental data (ALADIN/INDRA)  Useful tool in studying formation of hypernucei in spectator fragmentation Hybrid approach (GiBUU+SMM)  pre-equilibrium dynamics: relativistic GiBUU  asymptotic equilibrated stage: statistical decay by means of SMM for spectator matter (break-up of fireball within coalescence picture due to rapid expansion) Theoretical estimation for future HypHI & J-PARC experiments  Xsections of light hypernucei from spectators in 12 C+ 12 C@2AGeV  Xsections of energetic light hypernuclei in p+ 12 C@50GeV Future/under progress developments  More consistent treatment of formation of hypernuclei, e.g. recently extended SMM-code including strangeness degrees of freedom (A. Botvina & J. Pochodzalla)