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Register a new userStrong force fields and stabilities of the nucleon and singly heavy baryon $Sigma_c$
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We investigate the strong force fields and stabilities of the nucleon and the singly heavy baryon $Sigma_c$ within the framework of the chiral quark-soliton model. Having constructed the pion mean fields in the presence of the $N_c-1$ level quarks self-consistently, we are able to examine the gravitational form factors of $Sigma_c$. We mainly focus in the present work on the stability conditions for both the nucleon and $Sigma_c$ and discuss the strong force fields and their physical implications. We also present the results for the gravitational form factors and relevant observables, emphasising the difference between the nucleon and $Sigma_c$.
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We study the isospin mass differences of singly heavy baryons, based on a pion mean-field approach. We consider both the electromagnetic interactions and the hadronic contributions that arise from the mass difference of the up and down quarks. The relevant parameters have been already fixed by the baryon octet. In addition, we introduce the strong hyperfine interactions between the light quarks inside a chiral soliton and the Coulomb interactions between the chiral soliton and a heavy quark. The numerical results are in good agreement with the experimental data. In particular, the results for the neutral mass relations, which contain only the electromagnetic contributions, are in remarkable agreement with the data, which implies that the pion mean field approach provides a good description of the singly heavy baryons.
The strong and radiative decays of the low-lying $lambda$-mode $D$-wave $Lambda_{c(b)}$, $Sigma_{c(b)}$, $Xi_{c(b)}$, $Xi_{c(b)}$, and $Omega_{c(b)}$ baryons are studied in a constituent quark model. Our calculation shows the following: (i) The missing $lambda$-mode $D$-wave $Omega_{c(b)}$, $Lambda_{b}$, and $Xi_{b}$ baryons have a relatively narrow decay width of a few MeV or a few tens of MeV and their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiments. (ii) The $lambda$-mode $1D$-wave excitations in the $Sigma_{c(b)}$ and $Xi_{c(b)}$ families appear to have a relatively broad width of $sim 50-200$ MeV.Most of the $1D$-wave states have large decay rates into the $1P$-wave heavy baryons via the pionic or kaonic strong decay processes, which should be taken seriously in future observations. (iii) Both $Lambda_c(2860)$ and $Xi_c(3050)$ seem to favor the $J^P=3/2^+$ excitation $|^2D_{lambdalambda} frac{3}{2}^+ rangle$ of $bar{mathbf{3}}_F$, while both $Lambda_c(2880)$ and $Xi_c(3080)$ may be assigned as the $J^P=5/2^+$ excitation $|^2D_{lambdalambda} frac{5}{2}^+ rangle$ of $bar{mathbf{3}}_F$. The nature of $Xi_c(3050)$ and $Xi_c(3080)$ could be tested by the radiative transitions $Xi_c(3055)^0to Xi_c(2790)^0 gamma$ and $Xi_c(3080)^0 to Xi_c(2815)^0 gamma$, respectively.
We study the electromagnetic form factors of the lowest-lying singly heavy baryons in a pion mean-field approach, which is also known as the SU(3) chiral quark-soliton model. In the limit of the heavy-quark mass, the dynamics inside a singly heavy baryon is governed by the $N_c-1$ valence quarks, while the heavy quark remains as a mere static color source. In this framework, a singly heavy baryon is described by combining the colored soliton with the singly heavy quark. In the infinitely heavy-quark mass limit, we can compute the electric quadrupole form factors of the baryon sextet with spin 3/2 with the rotational $1/N_c$ and linear corrections of the explicit flavor SU(3) symmetry breaking taken into account. We find that the sea-quark contributions or the Dirac-sea level contributions dominate over the valence-quark contributions in lower $Q^2$ region. We examined the effects of explicit flavor SU(3) symmetry breaking in detail. The numerical results are also compared with the recent data from the lattice calculation with the unphysical value of the pion mass considered, which was used in the lattice calculation.
We investigate the effects of the kaon cloud on the electromagnetic and axial-vector form factors of the $Omega^-$ baryon within the framework of the chiral quark-soliton model. We first derive the profile function of the chiral soliton in such a way that the kaon Yukawa tail is properly produced self-consistently. Then, we compute the electromagnetic form factors of the $Omega^-$ baryon. The results for the electromagnetic form factors are compared with the lattice data. We find that the results with kaon tail employed are in far better agreement with the lattice data. We also study the axial-vector form factors of the $Omega^-$ baryon, examining the effects of the kaon cloud.
We review the properties of quarkonia under strong magnetic fields. The main phenomena are (i) mixing between different spin eigenstates, (ii) quark Landau levels and deformation of wave function, (iii) modification of $bar{Q}Q$ potential, and (iv) the motional Stark effect. For theoretical approaches, we review (i) constituent quark models, (ii) effective Lagrangians, (iii) QCD sum rules, and (iv) holographic approaches.
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