The study of hypernuclei in the quark mean-field model are extended from single-$Λ$ hypernuclei to double-$Λ$ hypernuclei as well as $Ξ$ hypernuclei (double strangeness nuclei), with a broken SU(3) symmetry for the quark confinement potential. The strength of the potential for $u,d$ quarks is constrained by the properties of finite nuclei, while the one for $s$ quark is fixed by the single $Λ$-nucleus potential at the nuclear saturation density, which has a slightly different value. Compared to our previous work, we find that the introduction of such symmetry breaking improves efficiently the description of the single $Λ$ energies for a wide range of mass region, which demonstrates the importance of this effect on the hypernuclei study. Predictions for double-$Λ$ hypernuclei and $Ξ$ hypernuclei are then made, confronting with a few available experiential double-$Λ$ hypernuclei data and other model calculations. The consistency of our results with the available double-$Λ$ hypernucleus is found to be surprisingly good. Also, there is generally a bound state for $Ξ^0$ hypernuclei with both light and heavy core nuclei in our model.
We extend the quark mean field model to the study of $Λ$ hypernuclei. Without adjusting parameters, the properties of $Λ$ hypernuclei can be described reasonably well. The small spin-orbit splittings for $Λ$ in hypernuclei are achieved, while the $Λ$ single particle energies in the present model are slightly underestimated as compared with the experimental values. About 3% deviation from the quark model prediction for the $ω-Λ$ couplings is required in order to reproduce the experimental single particle energies.
We study the properties of double-$Λ$ hypernuclei in the relativistic mean-field theory, which has been successfully used for the description of stable and unstable nuclei. With the meson-hyperon couplings determined by the experimental binding energies of single-$Λ$ hypernuclei, we present a self-consistent calculation of double-$Λ$ hypernuclei in the relativistic mean-field theory, and discuss the influence of hyperons on the nuclear core. The contribution of two mesons with dominant strange quark components (scalar $σ^*$ and vector $ϕ$) to the $ΛΛ$ binding energy of double-$Λ$ hypernuclei i…
Energy levels of the double-$Λ$ hypernuclei $_Λ^{}$$_Λ^7$He, $_Λ^{}$$_Λ^7$Li, $_Λ^{}$$_Λ^8$Li, $_Λ^{}$$_Λ^9$Li, $_Λ^{}$$_Λ^9$Be and $_Λ^{}$$_Λ^{10}$Be are predicted on the basis of the $α+x+Λ+Λ$ four-body model with $x=n, p, d, t, ^3$He and $α$, respectively.
The most recent development of the quark-meson coupling (QMC) model, in which the effect of the mean scalar field in-medium on the hyperfine interaction is also included self-consistently, is used to compute the properties of finite hypernuclei. The calculations for $Λ$ and $Ξ$ hypernuclei are of comparable quality to earlier QMC results without the additional parameter needed there. Even more significantly, the additional repulsion associated with the increased hyperfine interaction in-medium completely changes the predictions for $Σ$ hypernuclei. Whereas in the earlier work they were bound b…
Properties of $Λ,~Ξ^0$ hypernuclei and neutron stars are investigated in quark mean field model with pion and gluon corrections. Firstly, $u, ~d$, and $s$ quarks are confined by relativistic harmonic oscillator potentials to generate the baryons, like nucleon, $Λ, ~Σ$, and $Ξ$ hyperons. The effects of pion-quark coupling and one-gluon exchange are considered perturbatively. Then, the baryons interact with each other through exchanging $σ, ~ω,$ and $ρ$ mesons between quarks in hypernuclei and nuclear matter. The strengths of confinement potentials for $u, ~d,$ and $s$ quarks are determined by t…
The quark mean-field (QMF) model is applied to study the single $Λ^+_c$ hypernuclei. The charm baryon, $Λ^+_c$, is constructed by three constituent quarks, $u, ~d$, and $c$, confined by central harmonic oscillator potentials. The confinement potential strength of charm quark is determined by fitting the experimental masses of charm baryons, $Λ^+_c,~Σ^+_c$, and $Ξ^{++}_{cc}$. The effects of pions and gluons are also considered to describe the baryons at the quark level. The baryons in $Λ^+_c$ hypernuclei interact with each other through exchanging the $σ,~ω$, and $ρ$ mesons between the quarks c…
We fit the $^1 S_0 ΛΛ$ interaction in the nuclear medium to the masses of the experimentally known double-$Λ$ hypernuclei: $^{\phantom{6}6}_{ΛΛ}$He, $^{10}_{ΛΛ}$Be and $^{13}_{ΛΛ}$B. We derive this effective interaction from OBE Jülich $ΛΛ$-type potentials and using both Hartree-Fock and variational approaches. We find that the inclusion of $ΛΛ$ correlations in the variational scheme leads to significant differences and a better understanding of the dynamical features of the system. We investigate the sensitivity of the binding energies and the mesonic decay widths of the above double-$Λ$ hype…
The non--mesonic weak decay of double--$Λ$ hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon--induced mechanism, $ΛN\to nN$, widely studied in single--$Λ$ hypernuclei, additional hyperon--induced mechanisms, $ΛΛ\to Λn$, $ΛΛ\to Σ^0 n$ and $ΛΛ\to Σ^-p$, are accessible in double--$Λ$ hypernuclei and are investigated here. As in previous works on single--$Λ$ 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 an…
We generalized our approach to the hypernuclei with $A=B=3$ containing one charm or one bottom quark. We derive the relativistic nine-quark equations using the dispersion relation technique. The hypernuclei as the system of interacting quarks and gluons are considered. The relativistic nine-quark amplitudes of hypernuclei, including the constituent quarks with the charm or bottom are calculated. The approximate solutions of these equations are obtained using a method based on the extraction of leading singularities of the amplitudes. The poles of the multiquark amplitudes allow us to determine…
We study the properties of the $Θ^+$ in nuclear matter and $Θ^+$ hypernuclei within the quark mean-field (QMF) model, which has been successfully used for the description of ordinary nuclei and $Λ$ hypernuclei. With the assumption that the non-strange mesons couple only to the $u$ and $d$ quarks inside baryons, a sizable attractive potential of the $Θ^+$ in nuclear matter is achieved as a consequence of the cancellation between the attractive scalar potential and the repulsive vector potential. We investigate the $Θ^+$ single-particle energies in light, medium, and heavy nuclei. More bound sta…
Hypernuclei $ ^4_Y He$, $ ^4_Y H$, $ ^4_{YY} He$, $ ^4_{YY} H$, where $Y=Λ$, $Σ_0$, $Σ_+$, $Σ_-$, A=4 are considered using the relativistic twelve-quark equations in the framework of the dispersion relation technique. Hypernuclei as the systems of interacting quarks and gluons are considered. The relativistic twelve-quark amplitudes of hypernuclei, including $u$, $d$, $s$ quarks are constructed. The approximate solutions of these equations are obtained using a method based on the extraction of leading singularities of the amplitudes. The poles of the multiquark amplitudes allow us to determine…
$0s$-orbit $Λ$ states in $p$-shell double-$Λ$ hypernuclei ($^{\ \,A}_{ΛΛ}Z$), $^{\ \,8}_{ΛΛ}\textrm{Li}$, $^{\ \,9}_{ΛΛ}\textrm{Li}$, $^{10,11,12}_{\ \ \ \ \ ΛΛ}\textrm{Be}$, $^{12,13}_{\ \ ΛΛ}\textrm{B}$, and $^{\,14}_{ΛΛ}\textrm{C}$ are investigated. Microscopic cluster models are applied to core nuclear part and a potential model is adopted for $Λ$ particles. The $Λ$-core potential is a folding potential obtained with effective $G$-matrix $Λ$-$N$ interactions, which reasonably reproduce energy spectra of $^{A-1}_{\,Λ}Z$. System dependence of the $Λ$-$Λ$ binding energies is understood by the…
Using the Hartree-Fock plus random-phase-approximation (HF+RPA), we study the impurity effect of $Λ$ hyperon on the collective vibrational excitations of double-$Λ$ hypernuclei. To this end, we employ a Skyrme-type $ΛN$ and $ΛΛ$ interactions for the HF calculations, and the residual interactions for RPA derived with the same interactions. We find that inclusion of two $Λ$ hyperons in $^{16}$O shifts the energy of the collective states towards higher energies. In particular, the energy of the giant monopole resonance of $^{\,\,18}_{ΛΛ}$O, as well as that of $^{210}_{ΛΛ}$Pb, becomes larger. This…
The $A$-dependence of the bond energy $ΔB_{ΛΛ}$ of the ${ΛΛ}$ hypernuclear ground states is calculated in a three-body ${Λ+ Λ+ {^{A}Z}}$ model and in the Skyrme-Hartree-Fock approach. Various ${ΛΛ}$ and $Λ$-nucleus or ${ΛN}$ potentials are used and the sensitivity of $ΔB_{ΛΛ}$ to the interactions is discussed. It is shown that in medium and heavy ${ΛΛ}$ hypernuclei, $ΔB_{ΛΛ}$ is a linear function of $r_Λ^{-3}$, where $r_Λ$ is rms radius of the hyperon orbital. It looks unlikely that it will be possible to extract ${ΛΛ}$ interaction from the double-$Λ$ hypernuclear energies only, the additional…
Low-lying hypernuclei $ ^3_ΛH$, $ ^3_ΣH$, $ ^3_ΛHe$, $ ^3_ΣHe$ are described by the relativistic nine-quark equations in the framework of the dispersion relation technique. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitudes are obtained. The relativistic nine-quark amplitudes of hypernuclei, including the quarks of three flavors ($u$, $d$, $s$) are calculated. The poles of these amplitudes determine the masses of hypernuclei. The mass of state $ ^3_ΛH$ with the isospin I=0 and the spin-parity $J^P=\frac{1}{2}^+$ is e…
The $Λ$-$Λ$ effective interaction, in the channel $L=S=0$, in the nuclear medium is fitted to the available binding energies, $B_{ΛΛ}$, of double $Λ$ hypernuclei: $^{6}_{ΛΛ}$He, $^{10}_{ΛΛ}$Be and $^{13}_{ΛΛ}$B. The mesonic decay of these hypernuclei is also investigated. Finally, this effective interaction is used to predict the binding energies and mesonic decays widths of heavier double $Λ$ hypernuclei.
We calculate the $ΛΛ\to YN$ transition rate of ${^{\phantomΛ6}_{ΛΛ}}$He by the hybrid picture, the $π$ and $K$ exchanges plus the direct quark processes. It is found that the hyperon-induced decay is weaker than the nucleon-induced decay, but the former may reveal the short-range mechanism of the weak transition and also give a clear signal of the strong $ΔI=3/2$ transition. The $ΛΛ\to Y N$ transition in double-$Λ$ hypernucleus is complement to the $ΛN \to NN$ transition as it occurs only in the J=0 channel, while the J=1 transition is dominant in the $ΛN \to NN$ case.
We study the binding of hypernuclei based on the latest version of quark-meson coupling model, and estimate the phtoproduction cross sections for the $^{12}$C($γ,K^+$)$^{12}_Λ$B reaction using the bound $Λ$ spinors obtained in the model.
The general character of 4-quark (mesonic) and strange 6-quark (baryonic) quark systems is very briefly reviewed a la Jaffe, i.e. in the MIT bag, and so far still possibly viable candidates are indicated. Concentration is on S=-2 systems. Traditionally, one employs the (K^-,K^+) reaction on a relatively light target and hopes to retain two units of strangeness on a single final state fragment. Alternatively, heavy ion reactions can be used to produce Lambda-hyperons copiously and one seeks to observe coalescence of two of these particles into the lightest S=-2 nucleus, the H-dibaryon. The comp…
Properties of hypernuclei $_{ΛΛ}^5$H and $_{ΛΛ}^5$He are studied in a two-channel approach with explicit treatment of coupling of channels ^3\text{Z}+Λ+Λand α+Ξ. Diagonal ΛΛand coupling ΛΛ-ΞN interactions are derived within G-matrix procedure from Nijmegen meson-exchange models. Bond energy ΔB_{ΛΛ} in $_{ΛΛ}^5$He exceeds significantly that in $_{ΛΛ}^5$H due to the channel coupling. Diagonal Ξαattraction amplifies the effect, which is sensitive also to Λ-core interaction. The difference of the ΔB_{ΛΛ} values can be an unambiguous signature of the ΛΛ-ΞN coupling in ΛΛhypernuclei. However, improv…
The single-$Ξ^-$ hypernuclei are studied using a quark mean field model. At the quark level, the $Ξ^-$ hyperon is composed of one $d$ quark and two $s$ quarks, which are confined by the harmonic oscillator potentials. In the case of hadrons, the baryons interact with each other by exchanging $σ, ~ω$, and $ρ$ mesons between quarks in different baryons. The single-$Ξ^-$ binding energies of $Ξ$ hypernuclei are investigated from $\ce{_{Ξ^{-}}^{12}Be}$ to $\ce{^{208}_{Ξ^-}Tl}$ using different parameter sets, which are determined by the ground-state properties of several stable nuclei and the empiri…
We investigate $S=-1$ and $-2$ hypernuclei with $A=4-8$ employing the Jacobi-NCSM approach and in combination with baryon-baryon interactions derived within the frame work of chiral effective field theory. The employed interactions are transformed using the similarity renormalization group (SRG) so that the low- and high-momentum states are decoupled, and, thereby,convergence of the binding energies with respect to model space can be significantly speeded up. Such an evolution is however only approximately unitary when the so-called SRG induced higher-body forces are omitted. We first explore …
The quark model description of the hyperon nucleon forces, especially the antisymmetric spin-orbit forces, is studied from the spin-flavor SU(6) and the flavor SU(3) symmetry point of view. It is pointed out that the quark exchange interaction predicts strong antisymmetric spin-orbit force between the hyperon and nucleon.
Contributions of the direct quark mechanism are studied in the nonmesonic weak decays of light hypernuclei. The $ΛN \to NN$ transition is described by the one pion exchange mechanism and the direct quark mechanism, induced by the four-quark vertices in the effective weak Hamiltonian. By employing a realistic wave function of the $Λ$ inside the hypernuclei, nonmesonic decay rates of $^4_Λ$H, $^4_Λ$He, and $^5_Λ$He are calculated. The results show that the direct quark mechanism is significantly large and gives a large $ΔI =3/2$ contribution in the J=0 channel. The relative phase between the one…
It is shown how the recent shell-model determination of Lambda-N spin dependent interaction terms in Lambda hypernuclei allows for a reliable deduction of Lambda-Lambda separation energies in Lambda-Lambda hypernuclei across the nuclear p shell. Comparison is made with the available data, highlighting 11(Lambda-Lambda)Be and 12(Lambda-Lambda)Be which have been suggested as possible candidates for the KEK-E373 Hida event.
Charmed (and bottom) hypernuclei are studied in the quark-meson coupling (QMC) model. This completes systematic studies of charmed ($Λ_c^+, Σ_c, Ξ_c$), and $Λ_b$ hypernuclei in the QMC model. Effects of the Pauli blocking due to the underlying quark structure of baryons, and the $Σ_c N - Λ_c N$ channel coupling are phenomenologically taken into account at the hadronic level in the same way as those included for strange hypernuclei. Our results suggest that the $Σ_c^{++}$ and $Ξ_c^+$ hypernuclei are very unlikely to be formed, while the $Λ_c^+$, $Ξ_c^0$ and $Λ_b$ hypernuclei are quite likely to…
The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both finite nuclei and infinite nuclear matter, is applied to a study of $Λ$ hypernuclei. With the assumption that the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, a very weak spin-orbit force in the $Λ$-nucleus interaction is achieved automatically. This is a direct consequence of the SU(6) quark model wave function of the $Λ$ used in the QMC model. Possible implications and extensions of the present investigation are also discussed.
The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both infinite nuclear matter and finite nuclei, is applied to a systematic study of $Λ, Σ$ and $Ξ$ hypernuclei. Assumptions made in the present study are, (i) the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, and (ii) an SU(6) valence quark model for the bound nucleons and hyperon. The model automatically leads to a very weak spin-orbit interaction for the $Λ$ in a hypernucleus. Effects of the Pauli blocking at the quark level, particularly in the ope…
We study the formation of single- and double-$Λ$ hypernuclei in antiproton-induced reactions relevant for the forthcoming PANDA experiment at FAIR. We use the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model with relativistic mean-fields for the description of non-equilibrium dynamics and the statistical multifragmentation model (SMM) for fragment formation. This combined approach describes the dynamical properties of strangeness and fragments in low energy $\bar{p}$-induced reactions fairly well. We then focus on the formation of double-$Λ$ hypernuclei in high energy $\bar{p}$-nucl…
We have investigated the properties of $Θ^{+}$ in nuclei within the framework of relativistic mean field. The coupling constants are educed with quark meson coupling model. There is strong attractive interaction for $Θ^{+}$-nucleus and $Θ^{+}$ can be bind in nuclei. The depth of optical potential for $Θ^{+}$ in nuclear matter is estimated.
We develop a method for calculating the doublet splittings of select ground-state single $Λ$-hypernuclei. This hypernuclear spectroscopy is conducted by supplementing the self-consistent single-particle equations with an effective interaction, which follows directly from the underlying lagrangian,to simulate the residual particle-hole interaction. Our previous investigation, performed using only the leading-order contributions to the particle-hole interaction, was inadequate. In the present work, this method is improved upon by increasing the level of truncation in the residual interaction to …
Hypernuclei have been studied within the framework of Relativistic Mean Field theory. The force FSU Gold has been extended to include hyperons. The effective hyperon-nucleon and nucleon-nucleon interactions have been obtained by fitting experimental energies in a number of hypernuclei over a wide range of mass. Calculations successfully describe various features including hyperon separation energy and single particle spectra of single-Λhypernuclei throughout the periodic table. We also extend this formalism to double-Λhypernuclei.
We present results of hypernuclei calculated in the latest quark-meson coupling (QMC) model, where the effect of the mean scalar field in-medium on the one-gluon exchange hyperfine interaction, is also included self-consistently. The extra repulsion associated with this increased hyperfine interaction in-medium completely changes the predictions for Σ hypernuclei. Whereas in the earlier version of QMC they were bound by an amount similar to Λ hypernuclei, they are unbound in the latest version of QMC, in qualitative agreement with the experimental absence of such states.
The improved quark mass density- dependent model, which has been successfully used to describe the properties of both finite nuclei and bulk nuclear matter, is extended to include the strange quark. The parameters of the model are determined by the saturation properties of bulk matter. Then the given parameter set is employed to investigate both the properties of strange hadronic matter and those of $Λ$ hypernuclei. Bulk strange hadronic matter consisting of nucleons, $Λ$- hyperons and $Ξ$- hyperons is studied under mean-field approximation. Among others, density dependence of the effective ba…
We develop a chiral SU(3) symmetric relativistic mean field (RMF) model with a logarithmic potential of scalar condensates. Experimental and empirical data of symmetric nuclear matter saturation properties, bulk properties of normal nuclei, and separation energies of single- and double-$Λ$ hypernuclei are well explained. The nuclear matter equation of state (EOS) is found to be softened by $σζ$ mixing which comes from determinant interaction. The neutron star matter EOS is further softened by $Λ$ hyperons.
We extend our Skyrme-Hartree-Fock (SHF) approach, which was used earlier to describe successfully the single-$Λ$ hypernuclei, to investigate the binding and the $ΛΛ$ bond energies of the double-$Λ$ hypernuclei. The nucleon-nucleon ($NN$) and $Λ$-nucleon ($ΛN$) interactions are taken from our previous study. For the $ΛΛ$ force several Skyrme-like potentials available in the literature have been used. We discuss the sensitivity of the calculated $ΛΛ$ binding and bond energies to the $ΛΛ$ and $ΛN$ force parameters. It is found that the existing $ΛΛ$ hypernuclear data do not allow to distinguish b…
The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B_8=N, Lambda, Sigma and Xi), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU_6 quark-model wave functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exch…
We study the production of $Ξ^-$-hypernuclei, $^{12}_{Ξ^{-}}$Be and $^{28}_{Ξ^{-}}$Mg, via the ($K^-,K^+$) reaction within a covariant effective Lagrangian model, employing the bound $Ξ^-$ and proton spinors calculated by the latest quark-meson coupling model. The present treatment yields the $0^\circ$ differential cross sections for the formation of simple s-state $Ξ^-$ particle-hole states peak at a beam momentum around 1.0 GeV/c with a value in excess of 1 $μ$b.
The separation energies of the isospin triplet $^7_Λ\mathrm{He}$, $^7_Λ\mathrm{Li^{*}}$, $^7_Λ$Be, and the $T=1/2$ doublet $^8_Λ$Li, $^8_Λ$Be are investigated within the no-core shell model. Calculations are performed based on a hyperon-nucleon potential derived from chiral effective field theory at next-to-leading order. The potential includes the leading charge-symmetry breaking (CSB) interaction in the $Λ$N channel, whose strength has been fixed to the experimentally known difference of the $Λ$ separation energies of the mirror hypernuclei $^4_Λ\mathrm{He}$ and $^4_Λ\mathrm{H}$. It turns ou…
Recent experiments have presented more accurate data on the $ΛΛ$-binding energies of a few $ΛΛ$- hypernuclei. This is important as the $ΛΛ$- bond energies ($ΔB_{ΛΛ}$) of double-$Λ$ hypernuclei provide a measure of the in-medium strength of the $ΛΛ$ interaction. A mass formula, optimized with the newly available $ΛΛ$ binding energy data, is used to estimate the binding energy and bond energy over a wide range of hypernuclei. The $ΔB_{ΛΛ}$ values calculated with this mass formula are in good agreement with the experimental data, predictions of the quark mean-field (QMF) model and the relativisti…
In the present work, the approach of Furnstahl, Serot, and Tang (FST) is extended to the region of nonzero strangeness in application to single-particle states in single $Λ$-hypernuclei. To include $Λ$'s, an additional contribution to their effective lagrangian is systematically constructed within the framework of FST. The relativistic Hartree (Kohn-Sham) equations are solved numerically, and least-square fits to a series of experimental levels are preformed at various levels of truncation in the extended lagrangian. The ground-state properties of any $Λ$-hypernuclei are then predicted. In add…
One of the main open problems in the physics of Lambda-hypernuclei is the lack of a sound theoretical interpretation of the large experimental values for the ratio Gn/Gp=G(Lambda n -> nn)/G(Lambda p -> np). To approach the problem, we have incorporated a one-meson-exchange model for the Lambda N -> nN transition in finite nuclei in an intranuclear cascade code for the calculation of single and double-coincidence nucleon distributions corresponding to the non-mesonic weak decay of 5_Lambda-He and 12_Lambda-C. Due to the elimination of interferences, two-nucleon coincidences are expected to give…
Neutron and proton driplines of single-$Λ$ and double-$Λ$ hypernuclei, $Ξ^{-}$ hypernuclei as well as normal nuclei are studied within a relativistic mean field approach using an extended form of the FSU Gold Lagrangian density. Hyperons are found to produce bound nuclei beyond the normal nuclear driplines. Radii are found to decrease in hypernuclei near the driplines, in line with observations in light $Λ$ hypernuclei near the stability valley, The inclusion of a $Ξ^{-}$ introduces a much larger change in radii than one or more $Λ$'s.
The J=1/2 iso-doublet double-$Λ$-hypernuclei, namely, ${}_{ΛΛ}^{5}$H and ${}_{ΛΛ}^{5}$He, are examined as the three-body cluster states, $ΛΛt$ ($t\equiv {}^3$H or triton) and $ΛΛh$ ($h\equiv {}^3$He or helion), respectively, in a model independent framework utilizing pionless halo effective theory. Both singlet and triplet states of the constituent $ΛT$ ($T\equiv t,h$) sub-system are used in the elastic channel for the study of $_Λ^4$H$-Λ$ and $_Λ^4$He$-Λ$ scattering processes. A prototypical leading order investigation using a sharp momentum cut-off regulator, irrespective of the type of the …
A quark-meson coupling model based on the quark model proposed by Bogoliubov for the description of the quark dynamics is developed and applied to the description of neutron stars. Starting from a su(3) symmetry approach, it is shown that this symmetry has to be broken in order to satisfy the constraints set by the hypernuclei and by neutron stars. The model is able to describe observations such as two solar mass stars or the radius of canonical neutron stars within the uncertainties presently accepted. If the optical potentials for $Λ$ and $Ξ$ hyperons in symmetric nuclear matter at saturatio…
We study the photoproduction of the ^12{_Lambda}B hypernucleus within a fully covariant effective Lagrangian based model, employing Lambda bound state spinors derived from the latest quark-meson coupling model. The kaon production vertex is described via creation, propagation and decay of N*(1650), N*(1710), and N*(1720) intermediate baryonic resonant states in the initial collision of the photon with a target proton in the incident channel. The parameters of the resonance vertices are fixed by describing the total and differential cross section data on the elementary gamma (p, K+) Lambda reac…
Recent progress has been experienced in the field of hypernuclear weak decay, especially concerning the ratio of the neutron- to proton-induced Lambda non-mesonic decay rates, G_n/G_p. Theoretical analyses of nucleon coincidence data have been performed in a finite nucleus framework. They led to the extraction of G_n/G_p values in agreement with pure theoretical estimates, thus providing an evidence for the solution of a longstanding puzzle. Here we present an alternative approach to the problem, based on a nuclear matter formalism extended to finite nuclei via the local density approximation.…
We extend the relativistic point coupling model to single-$Λ$ hypernuclei. For this purpose, we add $N$-$Λ$ effective contact couplings to the model Lagrangian, and determine the parameters by fitting to the experimental data for $Λ$ binding energies. Our model well reproduces the data over a wide range of mass region although some of our interactions yield the reverse ordering of the spin-orbit partners from that of nucleons for heavy hypernuclei. The consistency of the interaction with the quark model predictions is also discussed.
We first determine the Lambda-N S-wave phase shifts so as to reproduce the experimental Lambda separation energies of A=3, 4 Lambda-hypernuclei, and then construct three phase-equivalent Lambda-N potentials with different central repulsion. By the stochastic variational method with correlated Gaussian basis we perform an extensive calculation of ab initio type for the hypernuclei of up to A=6. The binding energies and the sizes of the Lambda-hypernuclei are very insensitive to the type of the phase-equivalent Lambda-N potentials. We use two different Lambda-Lambda potentials which both reprodu…
The binding energies of a range of nuclei and hypernuclei with atomic number A <= 4 and strangeness |s| <= 2, including the deuteron, di-neutron, H-dibaryon, 3He, Lambda 3He, Lambda 4He, and Lambda Lambda 4He, are calculated in the limit of flavor-SU(3) symmetry at the physical strange quark mass with quantum chromodynamics (without electromagnetic interactions). The nuclear states are extracted from Lattice QCD calculations performed with n_f=3 dynamical light quarks using an isotropic clover discretization of the quark-action in three lattice volumes of spatial extent L ~ 3.4 fm, 4.5 fm and …
A recently introduced relativistic nuclear energy density functional, constrained by features of low-energy QCD, is extended to describe the structure of hypernuclei. The density-dependent mean field and the spin-orbit potential of a $Λ$-hyperon in a nucleus, are consistently calculated using the SU(3) extension of in-medium chiral perturbation theory. The leading long-range $ΛN$ interaction arises from kaon-exchange and $2π$-exchange with a $Σ$-hyperon in the intermediate state. Scalar and vector mean fields, originating from in-medium changes of the quark condensates, produce a sizeable {\em…
We study the production of bound cascade hypernuclei via the (K-,K+) reaction on 12C and 28Si targets within a covariant effective Lagrangian model, employing the cascade bound state spinors derived from the latest quark-meson coupling model as well as Dirac single particle wave functions. The K+-cascade production vertex is described by excitation, propagation and decay of Lambda and Sigma resonance states in the initial collision of a K- meson with a target proton in the incident channel. The parameters of the resonance vertices are fixed by describing the available data on total and differe…
We generalize the Jacobi no-core shell model (J-NCSM) to study double-strangeness hypernuclei. All particle conversions in the strangeness $S=-1,-2$ sectors are explicitly taken into account. In two-body space, such transitions may lead to the coupling between states of identical particles and of non-identical ones. Therefore, a careful consideration is required when determining the combinatorial factors that connect the many-body potential matrix elements and the free-space two-body potentials. Using second quantization, we systematically derive the combinatorial factors in question for $S=0,…
Bound state properties of few single and double-$Λ$ hypernuclei is critically examined in the framework of core-$Λ$ and core+$Λ+Λ$ few-body model applying hyperspherical harmonics expansion method (HHEM). The $ΛΛ$ potential is chosen phenomenologically while the core-$Λ$ potential is obtained by folding a phenomenological $ΛN$ interaction into the density distribution of the core. The depth of the effective $ΛN$ potential is adjusted to reproduce the experimental data for the core-$Λ$ subsystem. The three-body Schrödinger equation is solved by hyperspherical adiabatic approximation (HAA) to ge…
Machine learning the single-$Λ$ hypernuclei with neural-network quantum states
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Fudan University（复旦大学现代物理研究所核物理与离子束应用教育部重点实验室）；State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University（北京大学物理学院核物理与技术国家重点实验室）；Graduate School of China Academy of Engineering Physics（中国工程物理研究院研究生部）；Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University（上海理论核物理研究中心（国家自然科学基金委与复旦大学））
Pairing correlations play a very important role in atomic nuclei. Although several effective pairing interactions have been used in mean field calculations for nucleons, little is known about effective pairing interactions for hyperons. Based on the quark model, we propose a relationship between effective pairing interactions for hyperons and for nucleons; e.g., for $Λ$s, the strength of the pairing interaction is 4/9 of that for nucleons. A separable pairing force of finite range which has been widely applied to describing pairing correlations in normal nuclei is used to investigate pairing e…
