Closed shell charmed hypernuclei $^5_{Λ_c}$Li, $^{17}_{Λ_c}$F, $^{41}_{Λ_c}$Sc, $^{57}_{Λ_c}$Cu, $^{133}_{Λ_c}$Sb and $^{209}_{Λ_c}$Bi are calculated within Hartree-Fock approach by using three different force sets derived from microscopic Brueckner-Hartree-Fock calculations of $Λ$ hypernuclei. Ground state properties (binding energies, $Λ_c$ separation energies, $Λ_c$ single particle energies and $Λ_c$ densities) of charmed nuclei are examined. Due to the Coulomb repulsion between protons and the $Λ_c$ baryon, charmed hypernuclei are most bound for $16\leq$A$\leq 41$, where $^{17}_{Λ_c}$F can be considered as an excellent candidate to measure charmed hypernuclei. The competition between the attractive nucleon-$Λ_c$ interaction and the Coulomb repulsion is discussed, and we compare $Λ$ and $Λ_c$ hypernuclei properties.
This reports our recent studies on changes in properties of heavy hadrons containing at least a charm or a bottom quark in nuclear matter, and that the results for the $Λ^+_c$ and $Λ_b$ hypernuclei are studied quantitatively. Comparisons are made with the results for the $Λ$ hypernuclei studied previously in the same approach. It is shown that although the scalar and vector potentials for the $Λ$, $Λ_c^+$ and $Λ_b$ in the hypernuclei multiplet with the same baryon numbers are quite similar, the wave functions obtained, e.g., for $1s_{1/2}$ state, are very different. The $Λ^+_c$ probability den…
We present a study of the nonmesonic weak decay (NMWD) of charmed hypernuclei using a relativistic formalism. We work within the framework of the independent particle shell model and employ a ($π$,$K$) one-meson-exchange model for the decay dynamics. We implement a fully relativistic treatment of nuclear recoil. Numerical results are obtained for the one-neutron-induced transition NMWD rates of the $_{Λ^{+}_{c}}^{12}$N. The effect of nuclear recoil is sizable and goes in the direction to decrease the nuclear decay rate. We found that the NMWD decay rate of $_{Λ^{+}_{c}}^{12}$N is of the same o…
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 binding energies of baryonic systems with quantum number charm or beauty and neutron excess (or large isospin) are estimated within the bound state version of the chiral topological soliton model. The procedure of the skyrmion rescaling is applied which is of importance for large enough flavor excitation energies (for heavy flavors). Inclusion of the flavor excitation energies into the minimization of the total mass of the baryonic state naturally leads to its decrease, and this effect increases with increasing flavor mass. Our results concerning the binding energies turned out to be partl…
The identification of flavored multiskyrmions with the ground states of known hypernuclei is successful for several of them, e.g. for isodoublet H(Lambda) - He(Lambda), A=4, isoscalars He(Lambda) (A=5) and Li(Lambda) (A=7). In other cases agreement is not so good, but the behaviour of the binding energy with increasing baryon number is in qualitative agreement with data. Charmed or beauty hypernuclei within this approach are predicted to be bound stronger than strange hypernuclei. This conclusion is stable against variation of poorly known heavy flavor decay constants.
Changes in properties of heavy hadrons with a charm or a bottom quark are studied in nuclear matter. Effective masses (scalar potentials) for the hadrons are calculated using quark-meson coupling model. Our results also suggest that the heavy baryons containing a charm or a bottom quark will form charmed or bottom hypernuclei, which was first predicted in mid 70's. In addition a possibility of $B^-$-nuclear bound (atomic) states is briefly discussed.
Having in mind its future extension for theoretical investigations related to charmed nuclei, we develop a relativistic formalism for the nonmesonic weak decay of single-$Λ$ hypernuclei in the framework of the independent-particle shell model and with the dynamics represented by the $(π,K)$ one-meson-exchange model. Numerical results for the one-nucleon-induced transition rates of ${}^{12}_Λ\textrm{C}$ are presented and compared with those obtained in the analogous nonrelativistic calculation. There is satisfactory agreement between the two approaches, and the most noteworthy difference is tha…
$Λ^+_c$ hypernuclei are expected to have binding energies and other properties similar to those of strange hypernuclei in view of the similarity between the quark structures of the strange and charmed hyperons, namely $Λ(uds)$ and $Λ^+_c (udc)$. One striking difference however occurs in their mesonic decays, as there is almost no Pauli blocking in the nucleonic decay of a charm hypernucleus because the final-state nucleons leave the nucleus at high energies. The nuclear medium nevertheless affects the mesonic decays of charm hypernucleus because the nuclear mean fields modify the masses of the…
Charmed nuclei are investigated utilizing $Λ_c N$ and $Σ_c N$ interactions that have been extrapolated from lattice QCD simulations at unphysical masses of $m_π= 410$--$570$ MeV to the physical point using chiral effective field theory as guideline. Calculations of the energies of $Λ_c$ single-particle bound states for various charmed nuclei from $^{\ 5}_{Λ_c}$Li to $^{209}_{Λ_c}$Bi are performed using a perturbative many-body approach. This approach allows one to determine the finite nuclei $Λ_c$ self-energy from which the energies of the different bound states can be obtained. Though the $Λ_…
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 explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from $^5_Λ$He to $^{11}_Λ$He and from $^7_Λ$Li to $^{12}_Λ$Li --- in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic vari…
We investigate the properties of the single Lambda hypernuclei within a Skyrme-Hartree-Fock (SHF) model. The parameters of the Skyrme type effective lambda-nucleon (Lambda N) interaction are obtained by fitting to the experimental Lambda binding energies of hypernuclei with masses spanning a wide range of the periodic table. Alternative parameter sets are also obtained by omitting nuclei below mass number 16 from the fitting procedure. The SHF calculations are performed for the binding energies of the Lambda single-particle states over a full mass range using the best fit parameter sets obtain…
The nonmesonic decay of $Λ$-hypernuclei provides access to the nonleptonic weak decay process $ΛN \to NN$, which is achievable only through the observation of hypernuclear ground-state decays. We continue the discussion of some specific cases which make it possible to detect a few exclusive transitions, namely, the stripping of nucleon from the ground state results in a resonance state decaying via emission of two clusters. Delayed clusters accompanying weak decay of light hypernuclei give a unique information on spin dependence of the weak decay matrix elements.
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…
We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons driven by a $c\to s,d$ transition at the quark level. Our results for the form factors are consistent with heavy quark spin symmetry constraints which are valid in the limit of an infinitely massive charm quark and near zero recoil. Only a few exclusive semileptonic decay channels have been theoretically analyzed before. For those cases we find that our results are in a reasonable agreement with previous calculations.
We discuss low-lying collective excitations of $Λ$ hypernuclei using the self-consistent mean-field approaches. We first discuss the deformation properties of $Λ$ hypernuclei in the $sd$-shell region. Based on the relativistic mean-field (RMF) approach, we show that the oblate deformation for $^{28}$Si nucleus may disappear when a $Λ$ particle is added to this nucleus. We then discuss the rotational excitations of $^{25}_Λ$Mg nucleus using the three-dimensional potential energy surface in the deformation plane obtained with the Skyrme-Hartree-Fock method. The deformation of $^{25}_Λ$Mg nucleus…
We use the self-consistent mean-field theory to discuss the ground state and decay properties of $Λ$ hypernuclei. We first discuss the deformation of $Λ$ hypernuclei using the relativistic mean-field (RMF) approach. We show that, although most of hypernuclei have a similar deformation parameter to the core nucleus, the shape of $^{28}$Si is drastically altered, from oblately deformed to spherical, if a $Λ$ particle is added to this nucleus. We then discuss the pionic weak decay of neutron-rich $Λ$ hypernuclei using the Skyrme Hartree-Fock + BCS method. We show that, for a given isotope chain, …
We address the $Λ$-hypernuclear `overbinding problem' in light hypernuclei which stands for a 1--3 MeV excessive $Λ$ separation energy calculated in $_Λ^5$He. This problem arises in most few-body calculations that reproduce ground-state $Λ$ separation energies in the lighter $Λ$ hypernuclei within various hyperon-nucleon interaction models. Recent pionless effective field theory nuclear few-body calculations are extended in this work to $Λ$ hypernuclei. At leading order, the $ΛN$ low-energy constants are associated with $ΛN$ scattering lengths and the $ΛNN$ low-energy constants are fitted to $…
We evaluate the widths for the strong decays $Σ_c\toΛ_c π$, $Σ_c^*\toΛ_c π$ and $Ξ_c^{*}\toΞ_c π$. The calculations have been done within a nonrelativistic constituent quark model with wave functions that take advantage of the constraints imposed by heavy quark symmetry. Partial conservation of axial current hypothesis allows us to determine the strong vertices from an analysis of the weak axial current matrix elements. Our results are in good agreement with experimental data.
The shapes of light normal nuclei and $Λ$ hypernuclei are investigated in the $(β, γ)$ deformation plane by using a newly developed constrained relativistic mean field (RMF) model. As examples, the results of some C, Mg, and Si nuclei are presented and discussed in details. We found that for normal nuclei the present RMF calculations and previous Skyrme-Hartree-Fock models predict similar trends of the shape evolution with the neutron number increasing. But some quantitative aspects from these two approaches, such as the depth of the minimum and the softness in the $γ$ direction, differ a lot …
We present a detailed formalism of the microscopic particle-rotor model for hypernuclear low-lying states based on a covariant density functional theory. In this method, the hypernuclear states are constructed by coupling a hyperon to low-lying states of the core nucleus, which are described by the generator coordinate method (GCM) with the particle number and angular momentum projections. We apply this method to study in detail the low-lying spectrum of $^{13}_{~Λ}$C and $^{21}_{~Λ}$Ne hypernuclei. We also briefly discuss the structure of $^{155}_{~~Λ}$Sm as an example of heavy deformed hyper…
The hypernuclei $^4_Λ$He and $^4_Λ$H provide important information on the hyperon-nucleon interaction. We present accurate Faddeev-Yakubovsky calculations for the $Λ$ separation energies of the $0^+$ ground and the $1^+$ excited states based on the Nijmegen SC YN interactions. We explicitly take the $Σ$ admixture into account. Mass differences of the baryons and the charge-dependence of the interaction are considered. The results show that the Nijmegen models cannot predict all separation energies simultaneously hinting to failures of the current interaction models.
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…
We consider the chiral Lagrangian for charmed baryon fields with $J^P =\frac{1}{2}^+$ or $J^P =\frac{3}{2}^+$ quantum numbers. A chiral expansion framework for the baryon ground state masses is worked out to N$^3$LO as to compute their dependence on the up, down and strange quark masses for finite box QCD lattice simulations. It is formulated in terms of on-shell meson and baryon masses. The convergence of such a scheme is illustrated with physical masses as taken from the PDG. The counter terms relevant at N$^3$LO are correlated systematically by large-$N_c$ sum rules to leading and subleadin…
We investigate the role of two- and three-body $Λ$-nucleon forces by computing the ground state of a few $Λ$-hypernuclei with the Auxiliary Field Diffusion Monte Carlo algorithm. Calculations have been performed for masses up to A=41, including some open-shell hypernuclei. The results show that the use of a bare hyperon-nucleon force fitted on the available scattering data yields a consistent overestimate of the $Λ$-separation energy $B_Λ$. The inclusion of a hyperon-nucleon-nucleon interaction systematically reduces $B_Λ$, leading to a qualitatively good agreement with experimental data over …
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…
New effective $ΛN$ interactions are proposed for the density dependent relativistic mean field model. The multidimensionally constrained relativistic mean field model is used to calculate ground state properties of eleven known $Λ$ hypernuclei with $A\ge 12$ and the corresponding core nuclei. Based on effective $NN$ interactions DD-ME2 and PKDD, the ratios $R_σ$ and $R_ω$ of scalar and vector coupling constants between $ΛN$ and $NN$ interactions are determined by fitting calculated $Λ$ separation energies to experimental values. We propose six new effective interactions for $Λ$ hypernuclei: DD…
We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons. The decays are driven by a $c\to s,d$ transition at the quark level. Our form factors are consistent with Heavy Quark Symmetry constraints. The latter are valid in the limit of infinitely heavy quark mass at zero recoil.
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…
We study the superdeformed (SD) states and corresponding SD hypernuclei of Ar isotopes with the multidimensionally-constrained relativistic mean field (MDC-RMF) models which can accommodate various shape degree of freedom. %The hyperon-nucleon $σ$-$Λ$ and $ω$-$Λ$ interactions are introduced %in the same covariant framework. We found that the density profiles of SD states in Ar isotopes show a strong localization with a ring structure near the surface, while the central part of the density is dilute showing a hole structure. This localization of SD density induces an appreciable deformation in …
We extend the relativistic Hartree-Fock (RHF) theory to study the structure of single-$Λ$ hypernuclei. The density dependence is taken in both meson-nucleon and meson-hyperon coupling strengths, and the induced $Λ$-nucleon ($ΛN$) effective interactions are determined by fitting $Λ$ separation energies to the experimental data for several single-$Λ$ hypernuclei. The equilibrium of nuclear dynamics described by the RHF model in normal atomic nuclei, namely, the balance between nuclear attractive and repulsive interactions, is then found to be drastically changed in single-$Λ$ hypernuclei, reveal…
We study the energy spectra of $Ξ$ hypernuclei $^{15}_Ξ$C and $^{12}_Ξ$Be with a relativistic mean field (RMF) model with meson exchange $ΞN$ interactions. The RMF parameters are optimized to reproduce the average energy of KINKA and IRRAWADDY events for the ground state and also the average energy of KISO and IBUKI events for the excited state in $^{15}_Ξ$C. The potential depth of average $ΞN$ mean field potential is found to be about $-12$ MeV in the nuclear matter limit. We further introduce the two-body $s$- and $p$-wave interactions between valence nucleons and $Ξ$ particle. We found that…
In this work we study the possible QCD exotic states in the doubly charmed baryon sector. Within chiral effective theory, it is predicted that several excited baryons result from the $S$-wave scattering of ground-state doubly charmed baryons ($Ξ_{cc}^{++}, Ξ_{cc}^{+}, Ω_{cc}^{+}$) and light pseudoscalar mesons ($π, K, η$). The excited doubly charmed baryons can be classified by the strangeness ($S$) and isospin ($I$) quantum numbers. Two of the excited states are clearly exotic, in the sense that they cannot be explained by the conventional baryons with three quarks, since their quantum number…
Starting with a confining linear Lorentz scalar potential V_s and a Lorentz vector potential V_v which is also linear but has in addition a color-Coulomb attraction piece, -alpha_s/r, we solve the Dirac equation for the ground-state c- and u-quark wave functions. Then, convolving V_v with the u-quark density, we find that the Coulomb attraction mostly disappears, making an essentially linear barV_v for the c-quark. A similar convolution using the c-quark density also leads to an essentially linear tildeV_v for the u-quark. For bound cbar-c charmonia, where one must solve using a reduced mass f…
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…
Radiative decays of the 1$P$, 1$D$, 2$S$, and 2$P$ $Λ_c$ and 1$D$, 2$S$, and 2$P$ $Ξ_c$ charmed baryons
Tecnologico de Monterrey, Escuela de Ingenieria y Ciencias（蒙特雷理工学院，工程与科学学院）；Departamento de Física, DCI, Campus León, Universidad de Guanajuato（瓜纳华托大学，莱昂校区，物理系）；INFN, Sezione di Genova（意大利国家核物理研究所，热那亚分部）；Unidad Académica de Física, Universidad Autónoma de Zacatecas（萨卡特卡斯自治大学，物理学术单元）；Secretaría de Ciencia, Humanidades, Tecnología e Innovación（科学、人文、技术与创新秘书处）；Dual CP Institute of High Energy Physics（双CP高能物理研究所）
An accurate assessment of the hyperon-nucleon interaction is of great interest in view of recent observations of very massive neutron stars. The challenge is to build a realistic interaction that can be used over a wide range of masses and in infinite matter starting from the available experimental data on the binding energy of light hypernuclei. To this end, accurate calculations of the hyperon binding energy in a hypernucleus are necessary. We present a quantum Monte Carlo study of $Λ$ and $ΛΛ$ hypernuclei up to $A=91$. We investigate the contribution of two- and three-body $Λ$-nucleon force…
