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Production of fragments with finite strangeness in reactions wihtin a GiBUU+SMM combined approach

Production of fragments with finite strangeness in reactions wihtin a GiBUU+SMM combined approach. Th. Gaitanos, H. Lenske, U. Mosel. Introduction Theoretical aspects Formation of relativistic hypernuclei in simulations Non-equlibrium transport dynamics (Giessen-BUU)

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Production of fragments with finite strangeness in reactions wihtin a GiBUU+SMM combined approach

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  1. Production of fragments with finite strangeness in reactions wihtin a GiBUU+SMM combined approach Th. Gaitanos, H. Lenske, U. Mosel • Introduction • Theoretical aspects • Formation of relativistic hypernuclei in simulations • Non-equlibrium transport dynamics (Giessen-BUU) • Fragmentation mechanism (coalescence, statistical approaches, e.g. SMM) • Hybrid approach (GiBUU+SMM) • Applications • Benchmark: p+X@SIS/GSI (spallation reactions), X+X@SIS/GSI, (ALADIN) • X+X@2AGeV (HypHI), p+X@50GeV, X+X@20AGeV (J-PARC) • Final remarks Many thanks to GiBUU-group

  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 from BB->BYK (3-body PS) • 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. (http://theorie.physik.uni-giessen.de/GiBUU) • Asymptotic equilibrated stage • Fission/spallation, evaporation, multifragmentation… (with increasing excitation) • Statistical determination of partial decay widths  Monte-Carlo method • (basic method similar to numerical treatment of collisions in transport approaches) j,e E* Ai,Zi E*-e Ad,Zd Ad+n Ai Theoretical description (pre-equilibrium dynamics, statistical decay)… • Initial non-equilibrium stage • Relativistic transport equation of Boltzmann-type • Giessen-Boltzmann-Uehling-Uhlenbeck (GiBUU) Q.Li, J.Q. Wu, C.M. Ko, Phys. Rev. C39 (1989) 849 B. Blättel, V. Koch, U. Mosel, Rep. Prog. Phys. 56 (1993) 1 SMM code: Bondorf, Botvina & Mishustin, PR257(´95) 133

  5. Total energy (Etot=∫dxT00) of a „source“  Excitation energy: Eexc=Etot-Ebind, of a „source“ • local Pressures (Plong(x)=Tzz,Ptr(x)=Txx,yy)  Anisotropy ratios Qc (equilibration) Theoretical description (hybrid GiBUU+SMM approach)…

  6. Dynamical aspects in p+X and X+X reactions (properties of „fragmenting source“)… • Definition of residual nucleus: r>rsat/100. • Non-Equilibrium dynamics within GiBUU until system(s) approach local equilibrium at t=tf • Determination of A,Z and Eexc at time tf, and then apply SMM p+Au@0.8GeV Phys. Lett. B 663, 197 (2008)

  7. Benchmark-I: p+X reactions (global characteristics)… Exp. data: J. Benlliure et al., Nucl. Phys. A683 (2001) 513. F. Rejmund et al., Nucl. Phys. A683 (2001) 540 Charge distribution… Mass distribution… Phys. Lett. B 663, 197 (2008)

  8. Benchmark-I: p+X reactions (details)… Exp. data: J. Benlliure et al., Nucl. Phys. A683 (2001) 513. F. Rejmund et al., Nucl. Phys. A683 (2001) 540 Phys. Lett. B 663, 197 (2008)

  9. Pre-Equilibrium (BUU): high-energy n-emission, QE-pick • Asymptotic equilibreated state (SMM): Statistical decay of excited source • Final Result: Hybrid GiBUU+SMM Benchmark-I: p+208Pb@0.8GeV reactions (more details)… data: S. Leray et al., PRC65,044621 neutrons

  10. Dynamical aspects in p+p and 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 submitted (2008)

  11. Benchmark-II: X+X reactions (spectator fragmentation in Au+Au@0.4AGeV)… submitted (2008)

  12. Heavy System Light System Formation mechanism of spectator-hypernuclei …(X+X@3AGeV) • Hyperons formed from high- phase(pB->YK,BB->BYK+PYTHIA) rescattering with „spectator“-particles • captured by cold „spectator“-clusters with high probability, e.g. 4,6He •  In collisions of heavy nuclei (Au) difficult separation from pion-background (fireball) •  Possible in collisions of light systems (Ca+Ca,C+C) with minor problems of pion-background (Fireball)

  13. Hypernuclei from spectator fragmentation…(HypHI, 12C+12C@2AGeV) Formation of hypernuclei from spectator fragmentation via coalescence (condition: Y inside radius of fragmenting source+momentum coalescence) 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 submitted (2008)

  14. Hypernuclei from high energy proton-induced reactions…(J-PARC, p+12C@50GeV) submitted (2008) Two sources (residual target+moving source) Stable conditions after resonance decay Most of hyperons created & rescatter inside moving source

  15. Final remarks & Outlook… • Fragmentation in reactions within “hybrid” GiBUU+SMM •  BUU: non-equilibrium dynamics, info on onset of equilibration & instabilities •  Ground state stability important in extracting Ex •  SMM(Botvina/Mishustin): statistical decay of excited configuration • Fragmentation in proton-induced reactions & HIC •  GiBUU+SMM combined approach for fragmentation reactions •  reasonable description of a wide selection of exp. data • First transport predictions for future HypHI-project at GSI •  Light hyperfragment production from spectators with high probability • (however, coalescence picture too simple…) • Future/under progress developments •  Better description for strangeness sector of mean-field (in progress) •  Hyperfragment description more consistent: • GiBUU+HypSMM: would be an important extension for HypHI A.S. Botvina, J. Pochodzalla, Phys. Rev. C76 (2007) 024909.

  16. Relativistic Thomas-Fermi…

  17. Improved ground state in BUU…

  18. Transport equations of Boltzmann-type, very old story… • 1. Primer L. Boltzmann, Wien. Ber. 66 (1872) 275 • 2. Primer…L. Nordheim, Proc. R. Soc. London A119 (1928) 689 • E.A. Uehling, G.E. Uhlenbeck, Phys. Rev. 43 (1933) 552 • Theoretical background • Non-Relativistic kinetic theory • L.P. Kadanoff, G. Baym, „Quantum Statistical Mechanics“ (Benjamin, N.Y. 1962) • Relativistic kinetic theory • S.R. de Groot, W.A. van Leeuwen, C.G. van Weert • „Relativistic kinetic theory“ (North Holland, Amsterdam, 1980) • Modern Relativistic Quantum Transport Theory • W. Botermans, R. Malfliet, Phys. Rep. 198 (1990) 115 (difficult to understand…) • First applications to HIC… • P. Danielewicz, Ann. Phys. 152 (1984) 239 & 305 • G.F. Bertsch, S. Das Gupta, Phys. Rep. 160 (1988) 189 • First relativistic applications to HIC… • Giessen-group (PhD-Thesis of B. Blättel, V. Koch & U. Mosel/W. Cassing ~1990) • B. Blättel, V. Koch, U. Mosel, Rep. Prog. Phys. 56 (1993) 1 Q.Li, J.Q. Wu, C.M. Ko, Phys. Rev. C39 (1989) 849

  19. Spectator matter properties (BUU)… Nice stable conditions… …before instability sets in • Spectator very well suited for studies on fragments & hyperfragments

  20. Mean-field vs cascade – the role of the MDI…(J-PARC, p+12C@50GeV) central peripheral

  21. 136Xe+208Pb@1AGeV (spectator fragmentation…)

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