The $D^0$ decay into $K^0_s$ and a scalar resonance, $f_0(500)$, $f_0(980)$, $a_0(980)$, is studied obtaining the scalar resonances from final state interaction of a pair of mesons produced in a first step in the $D^0$ decay into $K^0_s$ and the pair of pseudoscalar mesons. This weak decay is very appropriate for this kind of study because it allows to produce the three resonances in the same decay in a process that is Cabibbo allowed, hence the rates obtained are large compared to those of $\bar{B}^0$ decays into $J/ψ$ and a scalar meson that have at least one Cabibbo suppressed vertex. Concretely the $a_0(980)$ production is Cabibbo allowed here, while it cannot be seen in the $\bar{B}^0_s$ decay into $J/ψa_0(980)$ and is doubly Cabibbo suppressed in the $\bar{B}^0$ decay into $J/ψa_0(980)$ and has not been identified there. The fact that the three resonances can be seen in the same reaction, because there is no isospin conservation in the weak decays, offers a unique opportunity to test the ideas of the chiral unitary approach where these resonances are produced from the interaction of pairs of pseudoscalar mesons.
Within the effective Lagrangian approach, we study the $p\bar{p} \rightarrow ψη$ [$ψ\equivψ(3686)$, $J/ψ$] reaction at the low energy where the contributions from nucleon pole and low-lying nucleon resonances, $N(1520)$, $N(1535)$ and $N(1650)$ are considered. All the model parameters are determined with the help of current experimental data on the decay of $ψ\to p \bar{p} η$. Within the model parameters, the total and differential cross sections of the $p\bar{p} \rightarrow ψη$ reaction are predicted. We show that the relative phases between different amplitudes of different nucleon resonance…
We have calculated coupling constants of a neutral pion with the lowest two nucleon resonances. This includes both the diagonal as well as non-diagonal coupling constants involving a nucleon resonance and a nucleon. For this, we first calculate vacuum-to-pion correlation function of the interpolating fields of two nucleons and then take its matrix elements with respect to a nucleon spinor and/or a nucleon resonance spinor(s). Using different QCD sum rules obtained from different matrix elements we eliminate unwanted coupling constants and solve for the desired ones. This is a simple extension …
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。
Toward establishing low-lying $Λ$ and $Σ$ hyperon resonances with the $\bar K + d \to π+ Y + N$ reaction
建立了一个$\bar K d \to πY N$与$Y=Λ, Σ$反应的模型，旨在通过对J-PARC E31实验数据的分析，建立低能级的$Λ$和$Σ$超子共振.由Kamano等人[Phys. Rev. C 90，065204（2014）]开发的动态耦合通道（DCC）模型产生的离壳振幅用作计算$\bar K d \to πY N$反应中的基本$\bar K N \to \bar K N$和$\bar K N \to πY$子过程的输入。结果表明，J-PARC E31实验具有相当高的输入- $\bar{K}$动量，$|\vec p_{\bar K}|= 1$ GeV，只有当输入$\bar K N \to \bar K N$振幅产生的$\bar KN$模型，如DCC模型在本次调查中使用，它描述的数据的$\bar K N$反应的能量远远超过$\bar K N$阈值，可以可靠地预测的横截面。我们发现，数据的三倍微分截面$dσ/(dM_{πΣ}dΩ_{p_n})$的$K^- d \to πΣn$反应低于$\bar K N$阈值可以用来测试与$Λ(1405)$相关的共振极点的预测。我们还发现，三倍微分截面的$K^- d \to π^- Λp$反应的动量依赖性，可以用来检查一个低躺$J^P=1/2^+$ $Σ$共振的存在与极质量$M_R = 1457 -i39$兆电子伏，这是发现从分析$K^-p$…
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…
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…
Here we investigate the decay patterns of the low-lying hidden strangeness nucleon resonances ($\equiv N_{s\bar{s}}$) to the strangeness channels by employing the chiral Lagrangian approach, where the $N_{s\bar{s}}$ states are treated as compact pentaquark states. The $S$-wave decays of these states to the $PB$ (pseudoscalar meson and baryon) and $VB$ (vector meson and baryon) channels are studied. According to the obtained masses and decay properties, we find four states, namely, $N_{s\bar{s}}(1874)$ with quantum numbers $I(J^{P})=1/2(1/2^{-})$, $N_{s\bar{s}}(1885)$ with $I(J^{P})=1/2(3/2^{-}…
Lattice calculations allow us to probe the low-lying, non-perturbative spectrum of QCD using first principles numerical methods. Here we present the low-lying spectrum in the scalar sector with vacuum quantum numbers including, in fully dynamical QCD for the first time, the mixing between glueball, q-qbar, and meson-meson operators.
Scalar glueball is implemented in single nonet linear sigma model (SNLSM) which basically includes lowest lying scalar and pseudoscalar mesons. Our new version of SNLSM involves mixing among scalar matter fields and glueball field which is enforced by scale symmetry considerations and the associated anomaly. Performing iterative Monte Carlo simulations, it is found that among the three candidates of scalar glueball, i.e., $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$, only $f_0(1500)$ is predominately a glueball state with the mass prediction of $1.566 \pm 0.046$ GeV and the other two are predomina…
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, …
The origin of the low-lying nature of the $N$*(1440), or Roper resonance, has been the subject of significant interest for many years, including several investigations using lattice QCD. The majority of lattice studies have not observed a low-lying excited state energy level in the region of the Roper resonance. However, it has been claimed that chiral symmetry could play an important role in our understanding of this resonance. The purpose of this study is to systematically examine the role of chiral symmetry in the low-lying nucleon spectrum by directly comparing the clover and overlap fermi…
Likelihood analysis of the newly observed $f_0(2020)$, $f_0(2330)$, and $f_0(2470)$ in $J/ψ\to γη^\primeη^\prime$ as high-lying unflavored scalar mesons
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 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.
We study the width of a two-body resonance in a coupled-channel system. We demonstrate how the width does not come only determined by the available phase space for its decay to the detection channel, but it greatly depends on the relative position of the mass of the resonance with respect to the masses of the coupled-channels generating the state. Our results are consistent with the experimental observation of narrow hadrons lying well above their lowest decay threshold.
Smooth transitions from hadronic matter to hot and dense matter of quantum chromodynamics accompany continuous transformations in effective degrees of freedom. The microscopic descriptions should include relativistic quarks interacting inside of hadrons. In this work we construct a schematic constituent quark model with relativistic kinematics which captures the global trends of meson spectra in the light, strange, and charm quark sectors. We examine the roles of the scalar- and vector-confining potentials as well as semishort range correlations in estimating the strength of central, spin-spin…
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.
