Nuclear models and the hypernuclear interaction

Physical Review C, 2013

Background: The calculation of the hyperon binding energy in hypernuclei is crucial to understanding the interaction between hyperons and nucleons. Purpose: We assess the relative importance of two-and three-body hyperon-nucleon force by studying the effect of the hyperon-nucleon-nucleon interaction in closed shell Λ hypernuclei from A = 5 to 91. Methods: The Λ binding energy has been calculated using the auxiliary field diffusion Monte Carlo method for the first time, to study light and heavy hypernuclei within the same model. Results: Our results show that including a three-body component in the hyperon-nucleon interaction leads to a saturation of the Λ binding energy remarkably close to the experimental data. In contrast, the two-body force alone gives an unphysical limit for the binding energy. Conclusions: The repulsive contribution of the three-body hyperon-nucleon-nucleon force is essential to reproduce, even qualitatively, the binding energy of the hypernuclei in the mass range considered.

Progress of Theoretical Physics Supplement, 2010

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.

Physics Essays, 1999

An alternative approach to the Standard Model is outlined, being motivated by the increasing theoretical and experimental difficulties encountered by this model, which furthermore fails to be unitary. In particular, the conceptual uneasiness generated by the excessive multiplicity of fundamental elements of the Quark Model, 36 different quarks whose cohesion needs 8 different types of gluons, has logically led some physicists to propose a variety of quark substructures in an effort to reach unity. However, these hazardous attempts will without any doubt guide particle physics to fall into an abyss, in view of the already too highly dubious content of QCD.

Physical Review Letters, 2013

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.

Frontiers of Physics, 2013

Based on a theory of extra dimensional confinement of quantum particles [E. R. Hedin, Physics Essays 25, 2 (2012)], a simple model of a nucleon-nucleon (NN) central potential is derived which quantitatively reproduces the radial profile of other models, without adjusting any free parameters. It is postulated that a higher-dimensional simple harmonic oscillator confining potential localizes particles into 3-d space, but allows for an evanescent penetration of the particles into two higher spatial dimensions. Producing an effect identical with the relativistic quantum phenomenon of zitterbewegung, the higher-dimensional oscillations of amplitude mc /  can be alternatively viewed as a localized curvature of 3-d space back and forth into the higher dimensions. The overall spatial curvature is proportional to the particle's extradimensional ground state wave function in the higher-dimensional harmonic confining potential well. Minimizing the overlapping curvature (proportional to the energy) of two particles in proximity to each other, subject to the constraint that for the two particles to occupy the same spatial location one of them must be excited into the 1 st excited state of the harmonic potential well, gives the desired NN potential. Specifying only the nucleon masses, the resulting potential well and repulsive core reproduces the radial profile of several published NN central potential models. In addition, the predicted height of the repulsive core, when used to estimate the maximum neutron star mass, matches well with the best estimates from relativistic theory incorporating standard nuclear matter equations of state. Nucleon spin, Coulomb interactions, and internal nucleon structure are not considered in the theory as presented in this article.

Nuclear Physics A, 1987

Variational calculations for n,6He, :Be and ,'iBe have been made with n,a-n,A cluster models. Various dA potentials are considered, all of which reproduce B,,(.:He). Some of the V,, are obtained from an evil model by a folding procedure using effective AN and ANN forces; realistic Van are also obtained from 4N-A Monte Carlo variational calculations of ,iHe. These MC V,, include many-body effects which give a central hump even with only AN forces. ;'Be is overbound by about one MeV with realistic IXY and aA potentials, even with reasonable estimates of AN exchange effects which give a reduction = 0.5 MeV. Repulsive ANN forces which can account for the overbinding of ,:He give rise to a repulsive a& potential which brings the calculated B, (ZBe) into good agreement with the experimental energy. The AA interaction strengths are obtained from ,,iHe and ,,'jBe for a number of AA potential shapes. The strengths obtained from ,l,tBe underbind ,,iHe by more than one MeV for all our AA and Cm potentials. The AA interaction obtained from the well established ,,'lBe event is found to be quite strongly attractive, comparable to the 'S, NN interaction without OPE, with correspondingly large negative AA scattering lengths of z-4 to-5 fm.

Brazilian Journal of Physics, 2017

This research article is a follow up of earlier work by M. Ikram et al., reported in International Journal of Modern Physics E 25, 1650103 (2016) wherein we searched for Λ magic numbers in experimentally confirmed doubly magic nucleonic cores in light to heavy mass region (ie. 16 O − 208 P b) by injecting Λ's into them. In present manuscript, working within the state-of-art relativistic mean field theory with inclusion of ΛN and ΛΛ interaction in addition to nucleon-meson NL3 * effective force, we extend the search of lambda magic numbers in multi-Λ hypernuclei using the predicted doubly magic nucleonic cores 292 120, 304 120, 360 132, 370 132, 336 138, 396 138 of elusive superheavy mass regime. In analogy to well established signatures of magicity in conventional nuclear theory, the prediction of hypernuclear magicity are made on the basis of one-, two-Λ separation energy (SΛ, S2Λ) and two lambda shell gaps (δ2Λ) in multi-Λ hypernuclei. The calculations suggest that the Λ numbers 92, 106, 126, 138, 184, 198, 240, and 258 might be the Λ shell closures after introducing the Λ's in elusive superheavy nucleonic cores. The appearance of new lambda shell closures other than the nucleonic ones predicted by various relativistic and non-relativistic theoretical investigations can be attributed to the relatively weak strength of spin-orbit coupling in hypernuclei compared to normal nuclei. Further, the predictions made in multi-Λ hypernuclei under study resembles quite closely with the magic numbers in conventional nuclear theory suggested by various relativistic and non-relativistic theoretical models. Moreover, in support of Λ shell closure the investigation of Λ pairing energy and effective Λ pairing gap has been made. We noticed a very close agreement of the predicted Λ shell closures with the survey made on the pretext of SΛ, S2Λ and δ2Λ except for the appearance of magic numbers corresponding to Λ = 156 which manifest in Λ effective pairing gap and pairing energy. Also, lambda single-particle spectrum is analyzed to mark the energy shell gap for further strengthening the predictions made on the basis of separation energies and shell gaps. Lambda and nucleon spin-orbit interactions are analyzed to confirm the reduction in magnitude of Λ spin-orbit interaction compared to the nucleonic case, however interaction profile is similar in both the cases. Lambda and nucleon density distributions have been investigated to reveal the impurity effect of Λ hyperons which make the depression of central density of the core of superheavy doubly magic nuclei. Lambda skin structure is also seen.

Journal of Physics G: Nuclear Physics, 1979

By considering the variation in core size, the A wavefunction, and accounting approximately for the centre-of-mass (CM) energy with mass number we have analysed the A binding energy of p-shell hypernuclei with charge-independent, central, spin-and statedependent effective A-nucleon potentials of gaussian form and Skyrme type within the shellmodel framework. The fits to the data in the present analysis indicate that in earlier analyses (Lee et ai 1970, Gal et ctl 1971, 1972) the roles of non-central and three-body forces have been over-emphasised, and so it is hard to place much reliance on the matrix elements of the A-nucleon force. Alternatively we may say that the effect of the non-central and three-body forces can be simulated by the spin and state dependence of the interaction. The effective potentials so obtained are used to estimate the well depth of A in nuclear matter and are found to give values in close agreement with the empirical estimates.

International Journal of Modern Physics E, 2016

In the present study, we search the [Formula: see text] magic number in hypernuclei within the framework of relativistic mean field (RMF) theory with inclusion of hyperon–nucleon and hyperon–hyperon potentials. Based on one- and two-lambda separation energy and two-lambda shell gaps, 2, 8, 14, 18, 20, 28, 34, 40, 50, 58, 68, 70 and 82 are suggested to be the [Formula: see text] magic numbers within the present approach. The relative weak strength of [Formula: see text] spin–orbit interaction is responsible for emerging the new lambda shell closures other than the model scheme. The predicted hypernuclear magicity quite resembles with nuclear magicity. In addition, the stability of hypernuclei is also examined by calculating the binding energy per particle, where Ni hypernucleus is found to be most tightly bound triply magic system in considered hypernuclei. Further, nucleon and lambda density distributions are analyzed and it is found that introduced [Formula: see text]’s have signif...

International Journal of Modern Physics E, 2015

We analyze the effects of δ–meson on hypernuclei within the framework of relativistic mean field theory. The δ–meson is included into the Lagrangian for hypernuclei. The extra nucleon–meson coupling (gδ) affects every piece of physical observables, like binding energy, radii and single-particle energies of hypernuclei. Magnitude of effects in hypernuclei is found to be relatively less than their normal nuclei because of the presence of Λ hyperon. Flipping of single-particle energy levels are observed with the strength of gδ in the considered hypernuclei as well as normal nuclei. The spin-orbit potentials are observed for considered hypernuclei and the effect of gδ on spin-orbit potentials is also analyzed. The calculated Λ binding energy (BΛ) are quite agreeable with experimental data. The sensitivity of BΛ for s- and p- orbitals with the strength of gδ is also analyzed. Lambda mean potential is investigated which is found to be consistent with other predictions.

Nuclear Physics A, 2005

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.

Brueckner theory is used to investigate the properties of hyperons in nuclear matter. The hyperon-nucleon interaction is taken from chiral effective field theory at next-to-leading order with SU(3) symmetric low-energy constants. Furthermore, the underlying nucleon-nucleon interaction is also derived within chiral effective field theory. We present the single-particle potentials of Λ and Σ hyperons in symmetric and asymmetric nuclear matter computed with the continuous choice for intermediate spectra. The results are in good agreement with the empirical information. In particular, our calculation gives a repulsive Σ-nuclear potential and a weak Λ-nuclear spin-orbit force.

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*

The non--mesonic weak decay of double--$\Lambda$ hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon--induced mechanism, $\Lambda N\to nN$, widely studied in single--$\Lambda$ hypernuclei, additional hyperon--induced mechanisms, $\Lambda \Lambda\to \Lambda n$, $\Lambda \Lambda\to \Sigma^0 n$ and $\Lambda \Lambda\to \Sigma^-p$, are accessible in double--$\Lambda$ hypernuclei and are investigated here. As in previous works on single--$\Lambda$ hypernuclei, we adopt a nuclear matter formalism extended to finite nuclei via the local density approximation and a one--meson exchange weak transition potential (including the ground state pseudoscalar and vector octets mesons) supplemented by correlated and uncorrelated two--pion--exchange contributions. The weak decay rates are evaluated for hypernuclei in the region of the experimentally accessible light hypernuclei $^{10}_{\Lambda\Lambda}$Be and $^{13}_{\Lambda\Lambda}$B. Our predictions are compared with...