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Production of (Hyper-)Fragments in Antiproton-Nucleus Collisions

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Strangeness production and hypernuclear dynamics in antiproton-nucleus collisions Zhao-Qing Feng (冯兆庆) Institute of Modern Physics (IMP), Lanzhou, CAS OUTLINE Introduction and motivation Transport approach for antiproton-nucleus collisions (LQMD) Particle production in antiproton induced reactions Nuclear fragmentation and isospin effect Summary IWND2018, Huzhou June 10-14 2 I. Introduction and motivation 1928, antiparticle predicted by Paul Dirac (1933 Nobel Prizer) 1932, positron was discovered by Carl David Anderson (1936 Nobel Prizer) 1955, Emilio Segre and Owen Chamberlain observed antiprotons in collisions of protons on copper at 6.2 GeV (1959 Nobel Prizers) 1984, Carlo Rubbia and Simon van der Meer found the particles W and Z0 at CERN in colliding of proton and antiproton in storage ring (1984 Nobel Prizers) As secondary beams, low-energy antiprotons (<5GeV/c) have been produced at CERN-LEAR, BNL, KEK in the world Anti-hypertriton, andp-p interaction by STAR collaboration The FAIR facility at GSI will provide high-intensity antiproton beams (15 GeV/c, starting operation in 2025?) IWND2018, Huzhou June 10-14 3 home.cern/about/accelerators/low-energy-antiproton-ring Low Energy Antiproton Ring at CERN (1982-1996) Proton Synchrotron (PS), Antiproton Collector (AC), Antiproton Accumulator (AA) Physics: highly excited nucleus, delayed fission process, cold QGP, hadrons in-medium PANDA detector from http://www-panda.gsi.de/ PANDA(antiProton ANnihilation at Darmstadt) Physics purpose: Hadron Spectroscopy, Nucleon Structure, Hadron in Baryonic Matter, Hypernucleus IWND2018, Huzhou June 10-14 4 Nuclear reactions induced by antiprotons H. Tamura, Prog. Theor. Exp. Phys. (2012) 02B012 Cold quark-gluon plasma: prediction Particle production and transportation In-medium effects of hadrons (pion, etc) Decay modes of highly excited nucleus Isospin effect at sub-saturation density Delayed fission induced by antiproton annihilation in heavy nuclei IWND2018, Huzhou June 10-14 5 “Cold quark-gluon plasma” PLB207 (1988) 371 IWND2018, Huzhou June 10-14 6 Description of antiproton-nucleus collisions: Kinetic approach (C. M. Ko and R. Yuan, Phys. Lett. B 192, 31 (1987)) Intranuclear cascade (INC) model (J. Cugnon et al., Phys. Rev. C 41, 1701 (1990)) Statistical Multifragmentation Model (SMM) (J. P. Bondorf et al.,Phys. Rep. 257, 133 (1995)) Transport models (mean-field pot., all possible reaction channels) Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model (O. Buss et al., Phys. Rep. 512, 1 (2012)) Lanzhou quantum molecular dynamics model (Z. Q. Feng, Phys. Rev. C 89, 044617 (2014)) IWND2018, Huzhou June 10-14 7 II. Lanzhou Quantum Molecular Dynamics (LQMD) transport model Nuclear dynamics from 5 MeV/nucleon – 10 GeV/nucleon for HICs, antiproton (proton, , K, etc) Dynamics of low-energy heavy-ion collisions (dynamical interaction potential, barrier distribution, neck dynamics, fusion/caption excitation functions etc) Isospin physics at intermediate energies (constraining nuclear symmetry energy at sub- and supra- saturation densities in HICs and probing isospin splitting of nucleon effective mass from HICs) In-medium properties of hadrons in dense nuclear matter from heavy-ion collisions (extracting optical potentials, i.e., (1232), N*(1440), N*(1535)), hyperons (,,,) and mesons (,K,,,,), hypernucleus dynamics) Hadron (antiproton, proton, , K) induced reactions (hypernucleus production, e.g., ()X, X, X, X(S=1), in-medium modifications of hadrons, cold QGP) IWND2018, Huzhou June 10-14 8 Nuclear dynamics induced by antiprotons fragmentation nucleus pion cloudy p Particle multiplicities on different nuclei at stopped energy Nuclei + 0 - K+/K0 K-/K0 +0 + - 12C 0.6 1.2 1.5 0.027/0.034 0.013/0.008 0.021 0.009 0.01 197Au 0.8 1.4 1.6 0.045/0.051 0.01/0.007 0.051 0.011 0.017 IWND2018, Huzhou June 10-14 9 Mean-field potentials for antiprotons, resonances, hyperons and mesons 1. Mean-field potentials for resonances ((1232), N*(1440), ) are considered based on nucleon potentials, but distinguishing isospin effects 2. Mean-field potentials for hyperons and antiprotons in nuclear medium A factor ξ is introduced in evaluating self-energies of the antinucleon, e.g., ξ=0.25 for VNN= -160 MeV at = 0 IWND2018, Huzhou June 10-14 10 IWND2018, Huzhou June 10-14 11 Particle production channels in the LQMD model Reaction channels with antiproton: pN NN , Statistical model with SU(3) symmetry for annihilation (E.S. Golubeva et al., Nucl. Phys. A 537, 393 (1992)) and resonances ((1232), N*(1440), N*(1535), ) production: Collisions between resonances, NN*N, NN*NN* Strangeness channels: The PYTHIA and FRITIOF code are used for baryon(meson)-baryon and antibaryon-baryon collisions at high invariant energies IWND2018, Huzhou June 10-14 12 Pion-nucleon scattering Z. Q. Feng, Phys. Rev. C 94, 054617 (2016) max= IWND2018, Huzhou June 10-14 13 III (1) Particle production in antiproton-nucleus collisions Z. Q. Feng and H. Lenske, Phys. Rev. C 89, 044617 (2014) pinc=4 GeV/c pinc=608 MeV/c LEAR (Low-Energy Antiproton Ring) at CERN (P. L. McGaughey et al., Phys. Rev. Lett. 56, 2156 (1986)) IWND2018, Huzhou June 10-14 14 Slope parameters: 105 MeV (pion), 140 MeV (kaon), 125 MeV (antikaon) and 95 MeV (hyperon) 0 12 20 40 112 KEK data: 13513 MeV (K S), 976 MeV () Multiplicities of particlesp+ C, Ne, Ca, Sn, (Phys. Rev. C 38 (1988) 2788) 181Ta, 197Au and 238U at 4 GeV/c IWND2018, Huzhou June 10-14 15 System size dependence of neutral particles at incident momentum of 4 GeV/c Z. Q. Feng, Nuclear Science and Techniques 26 (2015) S20512 IWND2018, Huzhou June 10-14 16 12 p+ C, 1 GeV/c p+40Ca, 4 GeV/c IWND2018, Huzhou June 10-14 17 In-medium effect: proton-nucleus and nucleus-nucleus collisions Z. Q. Feng et al., Phys. Rev. C 90 (2014) 064604 VK+(0)= 28 MeV, VK-(0)= -100 MeV 18 In-medium effect: strangeness production in HICs 19 (2) Nuclear fragmentation and hyperfragment formation in antiproton-nucleus collisions (Z. Q. Feng, Phys. Rev. C 93, 041601(R) (2016)) Experimental data: LEAR at CERN, IWND2018,B. Lott Huzhouet al., June Phys. 10-14 Rev. C 63, 034616 (2001) with 1.22 GeV20 antiproton Nuclear fragmentation with low-energy antiproton Z. Q. Feng, Phys. Rev. C 94, 064601 (2016) IWND2018, Huzhou June 10-14 21 Mass and charge distributions of nucleonic fragments produced in the p + 63Cu reaction at incident momenta of 105 MeV/c and 4 GeV/c, respectively The data from LEAR facility at CERN. J. Jastrzebski et al., Phys. Rev. C 47, 216 (1993) IWND2018, Huzhou June 10-14 22 Rapidity and kinetic energy distributions in collisions of antiproton on nuclei Classical coalescence approach IWND2018, Huzhou June 10-14 23 Hyperfragments production in the antiproton induced reactions Phys. Rev. C 93, 041601(R) (2016) IWND2018, Huzhou June 10-14 24 (3) Unexpected neutron/proton ratio and isospin effect in low-energy antiproton-induced reactions (Z. Q. Feng, Phys. Rev. C 96, 034607 (2017), arXiv: 1701.0630) LEAR data: D. Polster et al., Phys. Rev. C 51, 1167 (1995) IWND2018, Huzhou June 10-14 25 D. Polster et al., Phys. Rev. C 51, 1167 (1995) p+65Cu@200 MeV/c I. A. Pshenichnov, A. S. Iljinov, Y. S. Golubeva, and D. Polster, Phys. Rev. C 52, 947 (1995) IWND2018, Huzhou June 10-14 26 The n/p ratios in antiproton induced reactions with different stiffness of symmetry energies and compared with the LEAR data IWND2018, Huzhou June 10-14 27 VI. Summary Nuclear dynamics induced by antiprotons has been investigated within the Lanzhou quantum molecular dynamics (LQMD) model. Strangeness exchange reactions dominate the hyperon production in low- energy antiproton-nucleus collisions. Hyperons are captured by nucleonic fragmentations to form hypernuclide within a narrower rapidity and lower kinetic energy. The inclusive spectra of preequilibrium nucleons is thoroughly investigated within the model and a soft symmetry energy is concluded with s=0.5 IWND2018, Huzhou June 10-14 28 .
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