arXiv subjects
Publications and source records attributed to F. Huang.
The amplitudes for the pion-nucleon charge exchange reaction of the Karlsruhe-Helsinki and the George-Washington-University partial wave analyses are compared with those of a Regge-cut model with the aim to explore the possibility to provide high energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV.
The Euler equation (EE) is one of the basic equations in many physical fields such as fluids, plasmas, condensed matter, astrophysics, oceanic and atmospheric dynamics. A symmetry group theorem of the (2+1)-dimensional EE is obtained via a simple direct method which is thus utilized to find \em exact analytical \rm vortex and circumfluence solutions. A weak Darboux transformation theorem of the (2+1)-dimensional EE can be obtained for \em arbitrary spectral parameter \rm from the general symmetry group theorem. \rm Possible applications of the vortex and circumfluence solutions to tropical cyclones, especially Hurricane Katrina 2005, are demonstrated.
A preliminary investigation of the anti-K N interaction is performed within a chiral constituent quark model by solving the resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the S-, P-, D-, F-wave KN scattering phase shifts. The channel-coupling between anti-K N, pi Lambda and pi Sigma is considered, and the scattering phase shifts as well as the bound-state problem of anti-K N are dynamically studied. The results show that the S-wave anti-K N interaction in the isospin I=0 channel is attractive, and in the extended chiral SU(3) quark model such an attraction can make for an anti-K N bound state, which appears as a pi Sigma resonance in the coupled-channel calculation, while the chiral SU(3) quark model cannot accommodate the existence of an anti-K N bound state. It seems that the vector meson exchanges are necessary to be introduced in the quark-quark interactions if one tries to explain the Lambda(1405) as an anti-K N bound state or a pi Sigma - anti-K N resonance state.
The energies of the low-lying isoscalar and isovector ud anti-s anti-s configurations with spin-parity J^P=0^+, 1^+, and 2^+ are calculated in a non-relativistic constituent quark model by use of the variational method. The contributions of various parts of the quark-quark interacting potentials including the s-channel interaction are investigated, and the effect of different forms of confinement potential is examined. The model parameters are determined by the same method as in our previous work, and they still can satisfactorily describe the nucleon-nucleon scattering phase shifts and the hyperon-nucleon cross sections. The parameters of the s-channel interaction are fixed by the masses of K and K^* mesons, for which the size parameter is taken to be two possible values. When it is chosen as the same as baryons', the numerical results show that the masses of all the ud anti-s anti-s configurations are higher than the corresponding meson-meson thresholds. But when the size parameter for the K and K^* mesons is adjusted to be smaller than that for the baryons, the ud anti-s anti-s configuration with I=0 and J^P=1^+ is found to lie lower than the K^*K^* threshold, furthermore, this state has a very small KK^* component and the interaction matrix elements between this state and KK^* is comparatively small, thus its coupling to the KK^* channel will consequently be weak and it might be regarded as a possible tetraquark candidate.
The structure of Omega-pi state with isospin I=1 and spin-parity J^p=3/2^- are dynamically studied in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the energies of the baryon ground states, the binding energy of the deuteron, the nucleon-nucleon (NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The calculated results show that the Omega-pi state has an attractive interaction, and in the extended chiral SU(3) quark model such an attraction can make for an Omega-pi quasi-bound state with the binding energy of about several MeV.
The N Omega-bar systems with spin S=1 and S=2 are dynamically investigated within the framework of the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a good description of the energies of the baryon ground states, the binding energy of deuteron, and the experimental data of the nucleon-nucleon (NN) and nucleon-hyperon (NY) scattering processes. The results show that N Omega-bar states with spin S=1 and S=2 can be bound both in the chiral SU(3) and extended chiral SU(3) quark models, and the binding energies are about 28-59 MeV. When the annihilation effect is considered, the binding energies increase to about 37-130 MeV, which indicates the annihilation effect plays a relatively important role in forming an N Omega-bar bound state. At the same time, the N Omega-bar elastic scattering processes are also studied. The S, P, D partial wave phase shifts and the total cross sections of S=1 and S=2 channels have been calculated by solving the RGM equation for scattering problems.
Using the resonating group method (RGM), we dynamically study the baryon-meson interactions in chiral quark model. Some interesting results are obtained: (1) The Sigma K state has an attractive interaction, which consequently results in a Sigma K quasibound state. When the channel coupling of Sigma K and Lambda K is considered, a sharp resonance appears between the thresholds of these two channels. (2) The interaction of Delta K state with isospin I=1 is attractive, which can make for a Delta K quasibound state. (3) When the coupling to the Lambda K* channel is considered, the N phi is found to be a quasibound state in the extended chiral SU(3) quark model with several MeV binding energy. (4) The calculated S-, P-, D-, and F-wave KN phase shifts achieve a considerable improvement in not only the signs but also the magnitudes in comparison with other's previous quark model study.
By use of the resonating group method, the Delta K, Lambda K, and Sigma K states are further dynamically studied in the extended chiral SU(3) quark model based on our previous work. Similar to the results given by the original chiral SU(3) quark model, the calculated results here still show that the interactions of Delta K with isospin I=1 and Sigma K with isospin I=1/2 are attractive, which can consequently lead to Delta K and Sigma K quasibound states. When the channel coupling of Lambda K and Sigma K is considered, the calculated phase shifts show a sharp resonance between the thresholds of these two channels with spin-parity J^P=1/2^-.
The structure of the molecule-like state of $NKπ$ with spin-parity $J^π={3/2}^-$ and isospin I=1 is studied within the chiral SU(3) quark model. First we calculate the $NK$, $Nπ$, and $Kπ$ phase shifts in the framework of the resonating group method (RGM), and a qualitative agreement with the experimental data is obtained. Then we perform a rough estimation for the energy of $(NKπ)_{J^π={3/2}^-,I=1}$, and the effect of the mixing to the configuration $(ΔK)_{J^π={3/2}^-,I=1}$ is also considered. The calculated energy is very close to the threshold of the $NKπ$ system. A detailed investigation is worth doing in the further study.
The structures of N phi states with spin-parity J^{p}=3/2^- and J^p=1/2^- are dynamically studied in both the chiral SU(3) quark model and the extended chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a satisfactory description of the energies of the baryon ground states, the binding energy of the deuteron, the nucleon-nucleon (NN) scattering phase shifts, and the hyperon-nucleon (YN) cross sections. The channel coupling of N phi and Lambda K* is considered, and the effect of the tensor force which results in the mixing of S and D waves is also investigated. The results show that the N phi state has an attractive interaction, and in the extended chiral SU(3) quark model such an attraction plus the channel coupling effect can consequently make for an N phi quasi-bound state with several MeV binding energy.
The Euler equation (EE) is one of the basic equations in many physical fields such as the fluids, plasmas, condense matters, astrophysics, oceanic and atmospheric dynamics. A new symmetry group theorem of the two dimensional EE is obtained via a simple direct method and the theorem is used to find \em exact analytical \rm vortex and circumfluence solutions. Some types of Darboux transformations (DTs) for the both two and three dimensional EEs are obtained for \em arbitrary spectral parameters \rm which indicates that the EEs are integrable and the Navier-Stockes (NS) equations with large Renoyed number are nearly integrable, i.e, they are singular perturbations of the integrable EEs. The possibility of the vortex and circumfluence solutions to approximately explain the tropical cyclones (TCs), especially, the Hurricane Andrew 1992, is discussed.
The chiral SU(3) quark model is extended to include the coupling between the quark and vector chiral fields. The one-gluon exchange (OGE) which dominantly governs the short-range quark-quark interaction in the original chiral SU(3) quark model is now nearly replaced by the vector-meson exchange. Using this model, the isospin I=0 and I=1 kaon-nucleon S, P, D, F wave phase shifts are dynamically studied by solving the resonating group method (RGM) equation. Similar to those given by the original chiral SU(3) quark model, the calculated results for many partial waves are consistent with the experiment, while there is no improvement in this new approach for the P_{13} and D_{15} channels, of which the theoretical phase shifts are too much repulsive and attractive respectively when the laboratory momentum of the kaon meson is greater than 300 MeV.
The $S$-wave $ΛK$ and $ΣK$ states with isospin $I=1/2$ are dynamically investigated within the framework of the chiral SU(3) quark model by solving a resonating group method (RGM) equation. The model parameters are taken from our previous work, which gave a good description of the energies of the baryon ground states, the binding energy of the deuteron, and the experimental data of the nucleon-nucleon ($NN$) and nucleon-hyperon ($NY$) scattering. Assumed not to give important contributions in the scattering processes, the s-channel quark-antiquark ($q\bar q$) annihilation interactions are not included as a first step. The results show a strong attraction between $Σ$ and $K$, which consequently results in a $ΣK$ quasi-bound state with about 17 MeV binding energy, unlike the case of $ΛK$ which is unbound. When the channel coupling of $ΛK$ and $ΣK$ is considered, a sharp resonance state near 1670 MeV with spin-parity $J^P=1/2^-$ is found. The narrow gap of the $ΛK$ and $ΣK$ thresholds, the strong attraction between $Σ$ and $K$, and the sizeable off-diagonal matrix elements of $ΛK$ and $ΣK$ are responsible for the appearance of this resonance.
The structure of the $5q$ configuration states with strangeness ${\cal{S}}=+1$ is further studied in the chiral SU(3) quark model based on our previous work. We calculate the energies of fifteen low configurations of the $5q$ system, four lowest configurations of $J^π={1/2}^-$ with $4q$ partition $[4]_{orb}(0s^4)[31]^{σf}$, four of $J^π={1/2}^+$ with $4q$ partition $[31]_{orb}(0s^30p)[4]^{σf}$ and seven of $J^π={1/2}^+$ with $4q$ partition $[4]_{orb}(0s^30p)[31]^{σf}$. Some modifications are made in this further study, i.e., the orbital wave function is extended as an expansion of 4 different size harmonic oscillator forms; three various forms (quadratic, linear and error function form) of the color confinement potential are considered; the states with $4q$ partition $[4]_{orb}(0s^30p)[31]^{σf}$ are added, which are unnegligible in the $J^π={1/2}^+$ case and were not considered in our previous paper, further the mixing between configurations $[31]_{orb}(0s^30p)[4]^{σf}$ and $[4]_{orb}(0s^30p)[31]^{σf}$ is also investigated. The results show that the T=0 state is still always the lowest one for both $J^π={1/2}^-$ and $J^π={1/2}^+$ states, and $J^π={1/2}^-, T=0$ state is always lower than that of $J^π={1/2}^+$. All of these modifications can only offer several tens to hundred MeV effect, and the theoretical value of the lowest state is still about 245 MeV higher than the experimental mass of $Θ^+$. It seems to be difficult to get the calculated mass close to the observed one with the reasonable parameters in the framework of the chiral SU(3) quark model when the model space is chosen as a $5q$ cluster.
The $S$, $P$, $D$, $F$ wave $KN$ phase shifts have been studied in the chiral SU(3) quark model by solving a resonating group method equation. The numerical results of different partial waves are in agreement with the experimental data except for the cases of $P_{13}$ and $D_{15}$, which are less well described when the laboratory momentum of the kaon meson is greater than 400 MeV.
The isospin I=0 and I=1 kaon-nucleon $S$, $P$, $D$, $F$ wave phase shifts are studied in the chiral SU(3) quark model by solving the resonating group method (RGM) equation. The calculated phase shifts for different partial waves are in agreement with the experimental data. Furthermore, the structures of the $ΔK$ states with L=0, I=1 and I=2 are investigated. We find that the interaction between $Δ$ and $K$ in the case of L=0, I=1 is attractive, which is not like the situation of the $NK$ system, where the $S$-wave interactions between $N$ and $K$ for both I=0 and I=1 are repulsive. Our numerical results also show that when the model parameters are taken to be the same as in our previous $NN$ and $YN$ scattering calculations, the $ΔK$ state with L=0 and I=1 is a weakly bound state with about 2 MeV binding energy, while the one with I=2 is unbound in the present one-channel calculation.
The chiral SU(3) quark model is extended to include an antiquark in order to study the kaon-nucleon system. The model input parameters $b_u$, $m_u$, $m_s$ are taken to be the same as in our previous work which focused on the nucleon-nucleon and nucleon-hyperon interactions. The mass of the scalar meson $σ$ is chosen to be 675 MeV and the mixing of $σ_0$ and $σ_8$ is considered. Using this model the kaon-nucleon $S$ and $P$ partial waves phase shifts of isospin I=0 and I=1 have been studied by solving a resonating group method (RGM) equation. The numerical results of $S_{01}$, $S_{11}$, $P_{01}$, $P_{03}$, and $P_{11}$ partial waves are in good agreement with the experimental data while the phase shifts of $P_{13}$ partial wave are a little bit too repulsive when the laboratory momentum of the kaon meson is greater than 500 MeV in this present calculation.
The structure of the pentaquark state uudd-sbar is studied in the chiral SU(3) quark model as well as in the extended chiral SU(3) quark model, in which the vector meson exchanges are included. Four configurations of JP=1/2- and four of JP=1/2+ are considered. The results show that the isospin T=0 state is always the lowest one for both JP=1/2- and JP=1/2+ cases in various models. But the theoretical value of the lowest one is still about 200-300 MeV higher than the experimental mass of $Θ$. It seems that a dynamical calculation should be done for the further study.