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Register a new userBaryon spectra and non-strange baryon strong decays in the chiral SU(3) quark model
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In the framework chiral SU(3) quark model, the baryon spectra within the band of $Nleq 2$ are studied, and the effect of the confining potential in different configurations, namely the $Delta$-mode and Y-mode are compared. In the same way, the baryon spectra in the extended chiral SU(3) quark model, in which additional vector meson exchanges are introduced, are also calculated. It is shown that a reasonable baryon spectrum in the chiral SU(3) quark model can be achieved no matter whether the $Delta$-mode or the Y-mode confining potential is employed. In the extended chiral SU(3) quark model, several energy levels are further improved. The resultant binding energies of excited baryon states in different confining modes deviate just by a few to several tens MeV, and it is hard to justify which confining mode is the dominant one. The non-strange baryon strong decay widths are further discussed in the point-like meson emission model by using the wave-function obtained in the spectrum calculation. The resultant widths can generally explain the experimental data but still cannot distinguish which confining mode is more important in this simple decay mode.
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The strong decays of charm-strange baryons up to N=2 shell are studied in a chiral quark model. The theoretical predictions for the well determined charm-strange baryons, $Xi_c^*(2645)$, $Xi_c(2790)$ and $Xi_c(2815)$, are in good agreement with the experimental data. This model is also extended to analyze the strong decays of the other newly observed charm-strange baryons $Xi_c(2930)$, $Xi_c(2980)$, $Xi_c(3055)$, $Xi_c(3080)$ and $Xi_c(3123)$. Our predictions are given as follows. (i) $Xi_c(2930)$ might be the first $P$-wave excitation of $Xi_c$ with $J^P=1/2^-$, favors the $|Xi_c ^2P_lambda 1/2^->$ or $|Xi_c ^4P_lambda 1/2^->$ state. (ii) $Xi_c(2980)$ might correspond to two overlapping $P$-wave states $|Xi_c ^2P_rho 1/2^->$ and $|Xi_c ^2P_rho 3/2^->$, respectively. The $Xi_c(2980)$ observed in the $Lambda_c^+bar{K}pi$ final state is most likely to be the $|Xi_c ^2P_rho 1/2^->$ state, while the narrower resonance with a mass $msimeq 2.97$ GeV observed in the $Xi_c^*(2645)pi$ channel favors to be assigned to the $|Xi_c ^2P_rho 3/2^->$ state. (iii) $Xi_c(3080)$ favors to be classified as the $|Xi_c S_{rhorho} 1/2^+>$ state, i.e., the first radial excitation (2S) of $Xi_c$. (iv) $Xi_c(3055)$ is most likely to be the first $D$-wave excitation of $Xi_c$ with $J^P=3/2^+$, favors the $|Xi_c ^2D_{lambdalambda} 3/2^+>$ state. (v) $Xi_c(3123)$ might be assigned to the $|Xi_c ^4D_{lambdalambda} 3/2^+>$, $|Xi_c ^4D_{lambdalambda} 5/2^+>$, or $|Xi_c ^2D_{rhorho} 5/2^+>$ state. As a by-product, we calculate the strong decays of the bottom baryons $Sigma_b^{pm}$, $Sigma_b^{*pm}$ and $Xi_b^*$, which are in good agreement with the recent observations as well.
The reactions $Sigma_b^* to Lambda_b pi$, $Sigma_b to Lambda_b pi$, and $Xi_b^* to Xi_b pi$ are studied in the $^3P_0$ non-relativistic quark model with all the model parameters fixed in the sector of light quarks. The theoretical predictions for the decay widths $Gamma_{Sigma_b^* to Lambda_b pi}$ and $Gamma_{Sigma_b to Lambda_b pi}$ are consistent with the experimental data of the CDF Collaboration. Using as an input the recent mass of $Xi_b$ and the theoretical predictions mass of $Xi_b^{*}$, a narrow decay width about 1 MeV is predicted for the bottom baryon $Xi_b^*$. The work suggests that the $^3P_0$ quark dynamics is of independence of environments where heavy quarks may or may not be a component of baryons.
The weak and electromagnetic radiative baryon decays of octet $T_{8}$, decuplet $T_{10}$, single charmed anti-triplet $T_{c3}$ and sextet $T_{c6}$, single heavy bottomed anti-triplet $T_{b3}$ and sextet $T_{b6}$ are investigated by using SU(3) flavor symmetry irreducible representation approach. We analyze the contributions from a single quark transition $q_1to q_2gamma$ and $W$ exchange transitions, and find that the amplitudes could be easily related by SU(3) flavor symmetry in the $T_{b3,b6}$ weak radiative decays, $T_{c3,c6}$ weak radiative decays, $T_{10}to T_{8}gamma $ weak decays, $T_{10}to T_{10}gamma $ weak decays and $T_{10}to T_{8}gamma $ electromagnetic decays. Nevertheless, the amplitude relations are a little complex in the $T_{8}to T_{8}gamma$ and $T_{8}to T_{10}gamma$ weak decays due to quark antisymmetry in $T_{8}$ and $W$ exchange contributions. Predictions for branching ratios of $Lambda^{0}_bto ngamma$, $Xi^{-}_bto Xi^-gamma$, $Xi^{-}_bto Sigma^-gamma$, $Xi^{0}_bto Sigma^0gamma$, $Xi^{0}_bto Lambda^0gamma$, $Xi^{0}_bto Xi^0gamma$, $Xi^{*}to Xigamma$, $Sigma^{*0}to Sigma^{0}gamma$, $Delta^0to ngamma$ and $Delta^+to pgamma$ are given. The results in this work can be used to test SU(3) flavor symmetry approach in the radiative baryon decays by the future experiments at BESIII, LHCb and Belle-II.
We consider hadronic weak decays of beauty-baryons into charmless baryons and pseudoscalar mesons in a general framework based on $SU(3)$ decomposition of the decay amplitudes. The advantage of the approach lies in the ability to perform an $SU(3)$ analysis of these decays without any particular set of dynamical assumptions while accounting for the effects of an arbitrarily broken $SU(3)$ flavor symmetry. Dictated by the symmetries of the effective Hamiltonian that allow us to relate or neglect reduced $SU(3)$ amplitudes, we derive several sum rule relations between amplitudes and relations between $CP$ asymmetries in these decays and identify those that hold even if $SU(3)$ is broken.
We study the three-body anti-triplet ${bf B_c}to {bf B_n}MM$ decays with the $SU(3)$ flavor ($SU(3)_f$) symmetry, where ${bf B_c}$ denotes the charmed baryon anti-triplet of $(Xi_c^0,-Xi_c^+,Lambda_c^+)$, and ${bf B_n}$ and $M(M)$ represent baryon and meson octets, respectively. By considering only the S-wave $MM$-pair contributions without resonance effects, the decays of ${bf B_c}to {bf B_n}MM$ can be decomposed into irreducible forms with 11 parameters under $SU(3)_f$, which are fitted by the 14 existing data, resulting in a reasonable value of $chi^2/d.o.f=2.8$ for the fit. Consequently, we find that the triangle sum rule of ${cal A}(Lambda_c^+to nbar K^0 pi^+)-{cal A}(Lambda_c^+to pK^- pi^+)-sqrt 2 {cal A}(Lambda_c^+to pbar K^0 pi^0)=0$ given by the isospin symmetry holds under $SU(3)_f$, where ${cal A}$ stands for the decay amplitude. In addition, we predict that ${cal B}(Lambda_c^+to n pi^{+} bar{K}^{0})=(0.9pm 0.8)times 10^{-2}$, which is $3-4$ times smaller than the BESIII observation, indicating the existence of the resonant states. For the to-be-observed ${bf B_c}to {bf B_n}MM$ decays, we compute the branching fractions with the $SU(3)_f$ amplitudes to be compared to the BESIII and LHCb measurements in the future.
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