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Th. Gaitanos, H. Lenske, U. Mosel

Explore the production of hypernuclei in high-energy reactions through a hybrid approach combining GiBUU and SMM models. Learn about the theoretical framework, dynamical aspects, and benchmark experiments. Gain insight into the formation of exotic hypernuclei and the role of spectators. Discover the potential applications and future developments in this field of study.

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Th. Gaitanos, H. Lenske, U. Mosel

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  1. 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. Introduction… • Knowledge of YN & YY interaction (strangeness sector of hadronic EoS) ? • important for physics of neutron stars • „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) • So far mainly from nuclear structure studies • Info on properties of strange baryons in neutron rich matter needed •  e.g. (exotic) hypernuclei, e.g. 3HeY, 5HeY (Y=L,S) • Formation of (exotic?) hypernuclei accessible in high-energy reactions (p+X, X+X) • HypHI: 12C(6Li)+12C@SIS (in progress…) • J-PARC: p+12C@50GeV, 12C+12C@20AGeV (in future…) • PANDA: Antiproton-Nucleus (in future…)

  3. K L L,S,p,K,... L p p L L L,S,p,K,... K Relativistic Hypernuclei… • Production of Hypernuclei in Relativistic HIC • Production of many hyperons • Secondary rescattering (pN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/ • 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)… • Def. ofSpectators • Y(0)>0.75 (ALADIN)+r<rsat/100 • Spectators • Well defined conditions after onset of instability… • Anisotropy • …and onset of equilibration

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

  6. 12C+12C@2AGeV (HypHI)… Formation of hypernuclei from spectator fragmentation via coalescence (here only in coordinate space, e.g. condition: Y inside radius of fragmenting source) Note: extremely low total yields, e.g. orders of only view mb 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+12C@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+12C@50GeV (J-PARC) – theor. estimations on hypernuclei… Hypernuclei: Simple coalescence (Y inside source‘s) Prediction: production of energetic hypernuclei (Similar results for 12C+12C@20AGeV)

  9. 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 12C+12C@2AGeV •  Xsections of energetic light hypernuclei in p+12C@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)

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