The K−p→Σ0π0K^-p\to \Sigma^0\pi^0 reaction at low energies in a chiral quark model

A chiral quark-model approach is extended to the study of the $\bar{K}N$ scattering at low energies. The process of $K^-p\to \Sigma^0\pi^0$ at $P_K\lesssim 800$ MeV/c (i.e. the center mass energy $W\lesssim 1.7$ GeV) is investigated. This approach is successful in describing the differential cross sections and total cross section with the roles of the low-lying $\Lambda$ resonances in $n=1$ shells clarified. The $\Lambda(1405)S_{01}$ dominates the reactions over the energy region considered here. Around $P_K\simeq 400$ MeV/c, the $\Lambda(1520)D_{03}$ is responsible for a strong resonant peak in the cross section. The $\Lambda(1670)S_{01}$ has obvious contributions around $P_K=750$ MeV/c, while the contribution of $\Lambda(1690)D_{03}$ is less important in this energy region. The non-resonant background contributions, i.e. $u$-channel and $t$-channel, also play important roles in the explanation of the angular distributions due to amplitude interferences.Comment: 18 pages and 7 figure

Charmed baryon strong decays in a chiral quark model

Charmed baryon strong decays are studied in a chiral quark model. The data for the decays of $\Lambda^+_c(2593)$, $\Lambda^+_c(2625)$, $\Sigma^{++,+,0}_c$ and $\Sigma^{+,0}_c(2520)$, are accounted for successfully, which allows to fix the pseudoscalar-meson-quark couplings in an effective chiral Lagrangian. Extending this framework to analyze the strong decays of the newly observed charmed baryons, we classify that both $\Lambda_c(2880)$ and $\Lambda_c(2940)$ are $D$-wave states in the N=2 shell; $\Lambda_c(2880)$ could be $|\Lambda_c ^2 D_{\lambda\lambda}{3/2}^+>$ and $\Lambda_c(2940)$ could be $|\Lambda_c ^2 D_{\lambda\lambda}{5/2}^+>$. Our calculation also suggests that $\Lambda_c(2765)$ is very likely a $\rho$-mode $P$-wave excited state in the N=1 shell, and favors a $|\Lambda_c ^4P_\rho 1/2^->$ configuration. The $\Sigma_c(2800)$ favors being a $|\Sigma_c ^2P_\lambda{1/2}^->$ state. But its being |\Sigma^{++}_c ^4 P_\lambda{5/2}^-> cannot be ruled out.Comment: 22 pages, 16 tables; typos corrected;version to appear in PR

η′\eta' photoproduction on the nucleons in the quark model

A chiral quark-model approach is adopted to study the $\gamma p\rightarrow \eta'p$ and $\gamma n\rightarrow \eta' n$. Good descriptions of the recent observations from CLAS and CBELSA/TAPS are obtained. Both of the processes are governed by $S_{11}(1535)$ and $u$ channel background. Strong evidence of an $n=3$ shell resonance $D_{15}(2080)$ is found in the reactions, which accounts for the bump-like structure around $W=2.1$ GeV observed in the total cross section and excitation functions at very forward angles. The $S_{11}(1920)$ seems to be needed in the reactions, with which the total cross section near threshold for the $\gamma p\rightarrow \eta' p$ is improved slightly. The polarized beam asymmetries show some sensitivities to $D_{13}(1520)$, although its effects on the differential cross sections and total cross sections are negligible. There is no obvious evidence of the $P$-, $D_{13}$-, $F$- and $G$-wave resonances with a mass around 2.0 GeV in the reactions.Comment: 10 pages, 9 figure