Baryon-Baryon Interactions and Hypernuclei
thomas rijken2010, Progress of Theoretical Physics Supplement
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Abstract
The present status of hypernuclear physics is outlined and the future prospect of this field is described on the basis of the works presented in this volume.
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New directions in hypernuclear physics
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A hypernucleus, a sub-atomic bound system with at least one hyperon, is a great test ground to investigate nuclear forces and general baryonic interactions with up, down and strange quarks. Hypernuclei have been extensively studied for almost seven decades in reactions involving cosmic-rays and with accelerator beams. In recent years, experimental studies of hypernuclei have entered a new stage using energetic collisions of heavy-ion beams. However, these investigations have revealed two puzzling results related to the lightest three-body hypernuclear system, the so-called hypertriton and the unexpected existence of a bound state of two neutrons with a Λ hyperon. Solving these puzzles will not only impact our understanding of the fundamental baryonic interactions with strange quarks, but also of the nature of the deep interior of neutron stars. In this Perspective, we discuss approaches to solving these puzzles including experiments with heavy-ion beams and the analysis of nuclear emulsions using state-of-the-art technologies. We summarise ongoing projects and experiments at various facilities worldwide and outline future perspectives.
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1993
We present a first calculation of the potential and spin-orbit coupling for hypernuclei in the framework of a nuclear-potential model based on a spontaneous collective (superradiant) pion-nucleon-delta interaction. A perturbative evaluation of the propagation of a hyperon in such a coherent medium leads to an effective hypernuclear potential of the same shape and roughly half the depth (i.e. ~ 30 MeV) of the standard nuclear potential and a negligible spin-orbit coupling for both h and Z hypernuclei. Such results are in complete agreement with existing experimental data. Moreover, in this framework, we are able to explain the surprisingly narrow decay widths of the Z hypernuclei.
Future hypernuclear physics at MAMI-C and PANDA-GSI
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Hypernuclei represent the first steps towards an extension of the periodic system into the sector of strangeness and thus add a third dimension to our evolving picture of nuclei. They provide a large variety of new and exciting perspectives ranging from new dynamical symmetries in hypernuclei spectra, non-mesonic weak decays, and the interplay of the quark-exchange and meson-exchange aspects of strong baryon-baryon forces in the flavor SU(3) world. Furthermore, double hypernuclei may provide a doorway towards exotic quark states. In the near future, electroproduction experiments at TJNAF and MAMI-C will add more detailed information on the structure of single hypernuclei states. On the long term, experiments at the Japanese hadron facility and the high energy storage ring for antiprotons at the future GSI accelerator facility will allow us to extend high resolution γ-ray studies also into the domain of double hypernuclei.
Production and Interactions of Hyperons and Hypernuclei
2017
The production of strangeness on the nucleon and hyperon and hypernuclear production in heavy ion collisions at relativistic energies and in antiproton annihilation on nuclei is discussed. The reaction process is described by transport theory with focus on S = -2 channels and a comparison of different model interactions. The interactions of hyperons in nuclear matter is investigated in a novel SU(3) approach. An outlook to the S = -3 sector and Ω -physics is given.
Proceedings of The IX International Conference on Hypernuclear and Strange Particle Physics
2007
Exchange reactions with Dick Dalitz 11 A. Gal The hypernuclear physics heritage of Dick Dalitz (1925-2006) Spectroscopy of Hypernuclei 17 Y. Ma et al. γ-ray spectroscopy study of 11 Λ B and 12 Λ C* 21 M. Ukai et al. Observation of the 7 MeV excited spin-flip and nonspin-flip partners in 16 Λ O by γ-ray spectroscopy* 25 T. Koike et al. Next generation hypernuclear γ-ray spectrometer: Hyperball-J 29 J.J. LeRose et al. Hypernuclear spectroscopy in JLab's Hall A 33 S. Marrone et al. 9 Λ Li and 16 Λ N high resolution spectroscopy by electron scattering at Jefferson Lab in Hall A 37 F. Cusanno et al. High resolution hypernuclear spectroscopy at Jefferson Lab, Hall A: The experimental challenge 41 O. Hashimoto et al. Recent results of the JLab Hall C hypernuclear experiment E01-011 47 A. Margaryan RF picosecond timing technique and new possibilities for hypernuclear studies 51 S.N. Nakamura Future hypernuclear experiments at JLab 57 M. Agnello et al. The FINUDA Collaboration A study of 7 Λ Li production with FINUDA 61 P. Gianotti FINUDA: A hypernuclear factory 67 A. Feliciello One step beyond: Hypernuclear γ-ray spectroscopy with FINUDA 73 T. Nagae Strangeness nuclear physics at J-PARC 79 P. Achenbach Probing hypernuclei at PANDA and at MAMI-C 85 D.J. Millener Gamma decay studies of hypernuclei-Theoretical situation Weak Decays 93 M. Agnello et al. The FINUDA Collaboration Study of the proton weak decay of 12 Λ Cg.s. with FINUDA*
Hyperon-Nucleon Interactions from Quantum Chromodynamics and the Composition of Dense Nuclear Matter
Physical Review Letters, 2012
The low-energy nΣ − interactions determine, in part, the role of the strange quark in dense matter, such as that found in astrophysical environments. The scattering phase shifts for this system are obtained from a numerical evaluation of the QCD path integral using the technique of lattice QCD. Our calculations, performed at a pion mass of mπ ∼ 389 MeV in two large lattice volumes, and at one lattice spacing, are extrapolated to the physical pion mass using effective field theory. The interactions determined from QCD are consistent with those extracted from hyperon-nucleon experimental data within uncertainties, and strengthen theoretical arguments that the strange quark is a crucial component of dense nuclear matter.
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Hypernuclei with Stable Heavy Ion Beam and RI-beam Induced Reactions at GSI (HypHI) Hypernuclear Magnetic Moments and Exotic Hypernuclei
2000
In order to understand baryon-baryon interactions under flavored SU(3), one must investigate the interaction between nucleons and hyperons, which can be accessed so far mainly by studying hypernuclei. Since hyperons are expected to be one of the main ingredients of neutron dense matter such as neutron stars, understanding the interaction including hyperons is essential to understand our universe. Even though a number of new experimental techniques have been developed for the hypernuclear spectroscopy in the last decade, our knowledge is still limited to a small number of hypernuclei on/near the β-stability line. Magnetic moments of hypernuclei are very sensitive scope on the wave function of hyperons in hypernuclei, however, magnetic moments have never been measured on any of hypernuclei.
Possibility of a new neutral hypernucleus (n,n,Lambda,Lambda)
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The status of the light hypernuclei is reviewed, and discussed with models based either on the Nijmegen-RIKEN baryon--baryon interaction or on recent studies using chiral effective field theory. The latter suggests a significantly shorter range for the ΛΛ interaction, and this favours the formation of a Borromean state made of two neutrons and two hyperons. Various corrections are discussed, in particular the coupling of NΛ to NΣ, or of ΛΛ to NΞ, and the role of tensor forces. The new nucleus (n,n,Λ,Λ) could be produced in various reactions, in particular deuteron--deuteron scattering with the simultaneous production of two charged kaons, for which an estimate of the cross section is provided.
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We present an overview of a fully covariant formulation of describing the hypernuclear production with hadronic and electromagnetic probes. This theory is based on an effective Lagrangian picture and it focuses on production amplitudes that are described via creation, propagation and decay into relevant channel of N * (1650), N * (1710) and N * (1720) intermediate baryonic resonance states in the initial collision of the projectile with one of the target nucleons. The bound state nucleon and hyperon wave functions are obtained by solving the Dirac equation with appropriate scalar and vector potentials. Specific examples are discussed for reactions which are of interest to current and future experiments on the hypernuclear production.
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Prediction for hyper nuclei multiplicities from GSI to LHC energies from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model combined with a final state coalescence approach is presented and compared to the thermal model. The influence of the coalescence radius on the collision energy and centrality dependence of the Λ3H/Λ ratio is discussed.
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We present an overview of a fully covariant formulation for describing the production of strangeness-1 and-2 hypernuclei using probes of different kinds. This theory is based on an effective Lagrangian picture and it focuses on production amplitudes that are described via creation, propagation and decay into relevant channel of intermediate baryonic resonance states in the initial collision of the projectile with one of the target nucleons. The bound state nucleon and hyperon wave functions are obtained by solving the Dirac equation with appropriate scalar and vector potentials. Specific examples are discussed for reactions which are of interest to current and future experiments on the hypernuclear production. Keywords: strangeness-1 and-2 hyperon and hypernuclear production, Field theoretic model of (π + ,K +), (γ,K +) and (K − ,K +) reactions
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At the Mainz Microtron hypernuclei are produced by (e, e K) reactions. A dedicated kaon spectrometer located at 0 • with respect to the electron beam is used to detect kaons emitted in forward direction thus tagging events involving strangeness production. By measuring the momenta of pions from two body weak decays using high resolution magnetic spectrometers one gains direct access to the ground state masses of the produced hyperfragments. At FAIR the PANDA Collaboration intends to produce double-hypernuclei by numbers with an antiproton beam and study their high resolution γ-spectroscopy thus providing for the first time precise information on the level structure of these nuclei. The status of both experiments is reviewed.
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