We review some recent progress in our understanding of the lowest-lying spin-1/2 and spin-3/2 baryon magnetic moments (MMs) in terms of Chiral Perturbation Theory (ChPT). In particular, we show that at next-to-leading-order ChPT can describe the MMs of the octet baryons quite well. We also make predictions for the decuplet MMs at the same chiral order. Among them, the MMs of the $Δ^{++}$ and $Δ^+$ are found to agree well with data within the experimental uncertainties.
Two-body decay widths of lowest lying and next-to-lowest lying scalar and pseudoscalar mesons in generalized linear sigma model
在低能QCD的广义线性西格玛模型（GLSM）中研究了最低和次最低标量和赝标量介子的两体衰变宽度。这个模型考虑了“二夸克”和“四夸克”手征九元数的混合，并被用来研究QCD低能区的各种衰变和散射。本文给出了$Γ[f_0(980) \rightarrow K \bar{K}]$和$Γ[a_0(980) \rightarrow K \bar{K}]$的计算结果，并指出该模型能较好地预测最低层介子的两体衰变宽度，而对于次低层介子，只有部分衰变宽度与实验结果相符。我们将GLSM中预测的衰变宽度与单九态线性西格玛模型（SNLSM）中得到的结果进行了比较，表明手征九态混合大大改善了SNLSM对衰变宽度的预测。
The static properties and semileptonic decays of ground-state doubly heavy baryons are studied working in the framework of a non-relativistic quark model. Using a phenomenological potential model, we calculate the ground-state masses and magnetic moments of doubly heavy $ Ω$ and $ Ξ$ baryons. In the heavy quark limit, we introduce a simple form of the universal Isgur-Wise function used as the transition form factor and then investigate the exclusive $ b \rightarrow c $ semileptonic decay widths and branching ratios for $ \frac{1}{2}\rightarrow \frac{1}{2} $ baryon transitions. Our obtained res…
We have systematically calculated the strong decays of the low-lying $ρ$-mode $1P$-wave $Λ_{c(b)}$, $Σ_{c(b)}$, $Ξ_{c(b)}$, $Ξ^{'}_{c(b)}$, $Ω_{c(b)}$ baryons using the chiral quark model within the $j$-$j$ coupling scheme. For the controversial states, our results indicate: (i) For the singly charmed heavy baryons, the newly observed $Λ_{c}(2910)^+$ is a good candidate of the $J^P=5/2^-$ state $Λ_c|J^{P}=\frac{5}{2}^{-},2\rangle_ρ$. (ii) For the singly bottom heavy baryons, the $Ξ_{b}(6227)^-$ favors the $J^{P}=5/2^{-}$ state $Ξ_{b}|J^{P}=\frac{5}{2}^{-},2\rangle_ρ$. (iii) The other missing $…
The recently proposed $N^*(890)$ $1/2^-$ baryon is studied in a flavor $SU(3)$ scheme with $K$ matrix unitarization, by fitting to low energy cross section and phase shift data. It is found that $N^*(890)$ co-exists with low lying poles in other channels, which have been extensively discussed in the literature, though they belong to different octets, in the $SU(3)$ limit. Hence the existence of $N^*(890)$ is further verified.
We study pentaquark states of both light $q^4\bar q$ and hidden heavy $q^3 Q\bar Q$ (q = u,d,s quark in SU(3) flavor symmetry; Q = c, b quark) systems with a general group theory approach in the constituent quark model, and the spectrum of light baryon resonances in the ansatz that the $l=1$ baryon states may consist of the $q^3$ as well as $q^4\bar q$ pentaquark component. The model is fitted to ground state baryons and light baryon resonances which are believed to be normal three-quark states. The work reveals that the $N(1535)1/2^{-}$ and $N(1520)3/2^-$ may consist of a large $q^4\bar q$ co…
Excited state mass spectra of the low lying single charmed baryons with non strangeness have been calculated in a hypercentral approach. The six-dimensional hyperradial Schrödinger equation is solved by applying a simple variational method. We extend our scheme to predict the magnetic moments and the $ \frac{3}{2}^+ \rightarrow \frac{1}{2}^+ $ transition magnetic moments of $ Σ_{c} $ and $ Λ_{c} $ state baryons. A comparison of our results with the experimental data and predictions obtained in recent models is also presented.
In-medium properties of the low-lying baryons are studied in the quark-meson coupling (QMC) model, focusing on the $Σ_b$ and $Ξ_b$ baryons. It is predicted that the Lorentz-scalar effective mass of $Σ_b$ becomes smaller than that of $Ξ_b$ at moderate nuclear matter density, and as the density increases, namely, $m^*_{Σ_b} < m^*_{Ξ_b}$, although in vacuum $m_{Σ_b} > m_{Ξ_b}$. We also study the effects of the repulsive Lorentz-vector potentials on the excitation energies of these bottom baryons.
In this study, by combining the equal spacing rule with recent observations of $Ω_c(X)$ and $Ξ_c(X)$ baryons, we predict the spectrum of the low-lying $λ$-mode $1P$-wave excited $Σ_c$ states. Furthermore, their strong decay properties are predicted using the chiral quark model and the nature of $Σ_c(2800)$ is investigated by analyzing the $Λ_cπ$ invariant mass spectrum. The $Σ_c(2800)$ structure observed in the $Λ_c π$ mass spectrum was found to potentially arise from two overlapping $P$-wave $Σ_c$ resonances, $Σ_c(2813)3/2^-$ and $Σ_c(2840)5/2^-$. These resonances have similar decay widths of…
In-medium properties of the low-lying strange, charm, and bottom baryons in symmetric nuclear matter are studied in the quark-meson coupling (QMC) model. Results for the Lorentz-scalar effective masses, mean field potentials felt by the light quarks in the baryons, in-medium bag radii, and the lowest mode bag eigenvalues are presented for those calculated using the updated data. This study completes the in-medium properties of the low-lying baryons in symmetric nuclear matter in the QMC model, for the strange, charm and bottom baryons which contain one or two strange, one charm or one bottom q…
Stimulated by the newly discovered $Ω(2012)$ resonance at Belle II, in this work we have studied the OZI allowed strong decays of the low-lying $1P$- and $1D$-wave $Ω$ baryons within the $^3P_0$ model. It is found that $Ω(2012)$ is most likely to be a $1P$-wave $Ω$ state with $J^P=3/2^-$. We also find that the $Ω(2250)$ state could be assigned as a $1D$-wave state with $J^P=5/2^+$. The other missing $1P$- and $1D$-wave $Ω$ baryons may have large potentials to be observed in their main decay channels.
In this work, we adopt the $^3P_0$ model to investigate the strong decays of the low-lying doubly bottom baryons in the $j-j$ coupling scheme systematically. In this scheme, we construct the formulism of $^3P_0$ model under the spectator assumption, and then the heavy diquark symmetry is preserved automatically. Our results show that some of the $λ$-mode $Ξ_{bb}(1P)$ and $Ω_{bb}(1P)$ states are narrow, which have good potentials to be observed by future experiments. For the low-lying $ρ$-mode and $ρ$-$λ$ hybrid states, the Okubo-Zweig-Iizuka-allowed strong decays are highly suppressed and they…
Effective quark model with chiral U(3)XU(3) symmetry for baryon octet and decuplet
我们提出了一个有效的夸克模型，它适用于由QCD激发的具有线性上升禁闭势的低位重子八重态和十重态，并结合了手征U（3）XU（3）对称性线性实现的扩展Nambu-Jona-Lasinio（ENJL）模型。重子被认为是外部重态，通过ENJL-模型中定义的夸克-介子相互作用与具有固定旋量结构的局部三夸克流耦合并与低位介子耦合。在组分夸克圈表象中，我们计算了（pi NN），（pi N Delta）和（gamma N Delta）相互作用的耦合常数以及（sigma_{πN}）项。所得结果与实验数据和其它有效场论方法相符合。
We study the structure of the $Λ_c(2595)$ and $Λ_c(2625)$ resonances in the framework of an effective field theory consistent with heavy quark spin and chiral symmetries, that incorporates the interplay between $Σ_c^{(*)}π-ND^{(*)}$ baryon-meson degrees of freedom and bare P-wave $c\bar ud$ quark-model states. We show that these two resonances are not HQSS partners. The $J^P= 3/2^-$ $Λ_c(2625)$ should be viewed mostly as a dressed three quark state, whose origin is determined by a bare state, predicted to lie very close to the mass of the resonance. The $J^P= 1/2^-$ $Λ_c(2595)$ seems to have, …
