arXiv subjects
Publications and source records attributed to Xiao-Lin Chen.
Some charmonium-like resonances such as X(3872) can be interpreted as possible $D^{(*)}D^{(*)}$ molecular states. Within the quark model, we study the structure of such molecular states and the similar $B^{(*)}B^{(*)}$ molecular states by taking into account of the light meson exchange ($π$, $η$, $ρ$, $ω$ and $σ$) between two light quarks from different mesons.
The open-flavor strong decays are studied based on the interaction of potential quark model. The decay process is related to the s-channel contribution of the same scalar confinment and one-gluon-exchange(OGE) interaction in the quark model. After we adopt the prescription of massive gluons in time-like region from the lattice calculation, the approximation of four-fermion interaction is applied. The numerical calculation is performed to the meson decays in $u$, $d$, $s$ light flavor sector. The analysis of the $D/S$ ratios of $b_1\rightarrow ωπ$ and $a_1\rightarrow ρπ$ show that the scalar interaction should be dominant in the open-flavor decays.
We study the fine splitting in charmonium spectrum in quark model with the channel coupling effect, including $DD$, $DD^*$, $D^*D^*$ and $D_sD_s$, $D_sD_s^*$, $D_s^*D_s^*$ channels. The interaction for channel coupling is constructed from the current-current Lagrangian related to the color confinement and the one-gluon exchange potentials. By adopting the massive gluon propagator from the lattice calculation in the nonperturbative region, the coupling interaction is further simplified to the four-fermion interaction. The numerical calculation still prefers the assignment $1^{++}$ of X(3872).
The P-wave charm-strange mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ lie below the $DK$ and $D^\ast K$ threshold respectively. They are extremely narrow because their strong decays violate the isospin symmetry. We study the possible heavy molecular states composed of a pair of excited charm strange mesons. As a byproduct, we also present the numerical results for the bottonium-like analogue.
We study the possible heavy molecular states composed of a pair of charm mesons in the H and S doublets. Since the P-wave charm-strange mesons $D_{s0}(2317)$ and $D_{s1}(2460)$ are extremely narrow, the future experimental observation of the possible heavy molecular states composed of $D_s/D_s^\ast$ and $D_{s0}(2317)/D_{s1}(2460)$ may be feasible if they really exist. Especially the possible $J^{PC}=1^{--}$ states may be searched for via the initial state radiation technique.
The recently observed X(3872) resonance, which is difficult to be assigned a conventional $c\bar{c}$ charmonium state in the quark model, may be interpreted as a molecular state. Such a molecular state is a hidden flavor four quark state because of its charmonium-like quantum numbers. The s-channel one gluon exchange is an interaction which only acts in the hidden flavor multi-quark system. In this paper, we will study the X(3872) and other similiar hidden flavor molecular states in a quark model by taking into account of the s-channel one gluon exchange interaction.
In this paper we investigate the strong decays of the two newly observed bottom-strange mesons $B_{s1}(5830)$ and $B_{s2}^*(5840)$ in the framework of the quark pair creation model. The two-body strong decay widths of $B_{s1}(5830)^0\to B^{*+}K^-$ and $B_{s2}^*(5840)^0\to B^+K^-, B^{*+}K^-$ are calculated by considering $B_{s1}(5830)$ to be a mixture between $|^1P_1>$ and $|^3P_1>$ states, and $B_{s2}^*(5840)$ to be a $|^3P_2>$ state. The double pion decay of $B_{s1}(5830)$ and $B_{s2}^*(5840)$ is supposed to occur via the intermediate state $σ$ and $f_0(980)$. Although the double pion decay widths of $B_{s1}(5830)$ and $B_{s2}^*(5840)$ are smaller than the two-body strong decay widths of $B_{s1}(5830)$ and $B_{s2}^*(5840)$, one suggests future experiments to search the double pion decays of $B_{s1}(5830)$ and $B_{s2}^*(5840)$ due to their sizable decay widths.
Stimulated by recent observations of the excited bottom-strange mesons $B_{s1}$ and $B_{s2}^*$, we calculate the semileptonic decays $B_{s0}, B_{s1}^{\prime}, B_{s1}, B_{s2}^*\to [D_s(1968), D_{s}^*(2112), D_{sJ}(2317), D_{sJ}(2460)]\ell\barν$, which is relevant for the exploration of the potential of searching these semileptonic decays in experiment.
We study the possible tetraquark interpretation of light scalar meson states $a_0(980)$, $f_0(980)$, $κ$, $σ$ within the framework of the non-relativistic potential model. The wave functions of tetraquark states are obtained in a space spanned by multiple Gaussian functions. We find that the mass spectra of the light scalar mesons can be well accommodated in the tetraquark picture if we introduce a three-body quark interaction in the quark model. Using the obtained multiple Gaussian wave functions, the decay constants of tetraquarks are also calculated within the ``fall apart'' mechanism.
Babar Collaboration announced two new excited charmed baryons $Ξ_c(3055)^+$ and $Ξ_c(3123)^+$. We study their strong decays assuming they are D-wave states. Some assignments are excluded by comparing our numerical results with the experimental values of the total widths of $Ξ_c(3055)^+$ and $Ξ_c(3123)^+$. We also suggest some possible decay modes, which will be helpful to determine the properties of $Ξ_c(3055)^+$ and $Ξ_c(3123)^+$.
In $\XQM$, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to intepret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in $\XQM$ caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from $\XQM$, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities of the emission of Goldstone boson from a quark can give a reasonable interpretation to the flavor symmetry breaking in nucleon flavor-spin structure.
There has been important experimental progress in the sector of heavy baryons in the past several years. We study the strong decays of the S-wave, P-wave, D-wave and radially excited charmed baryons using the $^3P_0$ model. After comparing the calculated decay pattern and total width with the available data, we discuss the possible internal structure and quantum numbers of those charmed baryons observed recently.
We study the decay widths of the narrow resonances $D_{sj}^*(2317)$ and $D_{sj}(2460)$ in the chiral quark model, together with the well-known $D^\ast$ and $D_s^*$ mesons. All the parameters in our calculation are taken from Godfrey and Isgur's quark model except the $π^0-η$ mixing angle which is fixed by the $D_s^*$ decay widths. The calculated electromagnetic decay widths agree with those from other groups and the experimental data available quite well. However, the pionic decay widths of $D_{sj}(2317)$ and $D_{sj}(2460)$ are too small to fit the experimental data. We suspect that the simple chiral quark pion axial-vector interaction Hamiltonian is not suitable for hadron strong decays of $D_{sj}(2317)$ and $D_{sj}(2460)$.
Assuming X(3872) is a $qc \bar q \bar c$ tetraquark and using its mass as input, we perform a schematic study of the masses of possible heavy tetraquarks using the color-magnetic interaction with the flavor symmetry breaking corrections.
The chiral quark model gives a reasonably good description of many low-energy observables by incorporating the effective degrees carried by the constituent quarks and Goldstone bosons. We calculate the decuplet to octet transition magnetic moments and the decay widths of several excited hyperons using this model. The various radiative decay widths from the chiral quark roughly agree with experimental data including the recent JLAB measurement.
We estimate pionic decay widths of the narrow charm-strange resonances $D_{sj}(2317)$ and $D_{sj}(2460)$ using the $^3P_0$ model. Their one-pion decays occur through $η$-$π^0$ mixing while the two-pion decays of $D_{sj}(2460)$ occur through the virtual $f_0(980)$ meson. The mixing between $^3P_1$ and $^1P_1$ states enhances the single pion decay width of $D_{sj}(2460)$ and suppresses its double pion decay width significantly. The two-pion decay width of $D_{sj}(2460)$ is much smaller than its one-pion decay width. As a byproduct, we also calculate pionic decay widths of $B_{sj}(5765)$, $B_{sj}(5765)$ mesons in the $(0^+, 1^+)$ heavy doublet.
Using the color-magnetic interaction Hamiltonian with SU(3) flavor symmetry breaking, we perform a schematic study of the masses of the $J^P=1^+$ tetraquarks in the anti-decuplet representation. After diagonalizing the mass matrix, we find the $ud\bar s\bar s$ tetraquark lies around 1347 MeV. It decays into $K^+K^0π^0, K^+K^+π^-, K^0K^0π^+$ via P-wave. The dual suppression from the not-so-big three-body phase space and P-wave decay barrier may render this exotic state rather narrow. Future experimental exclusion of this state will cast doubt on the validity of applying the simple color-magnetic Hamiltonian to the multiquark system.
We have calculated the magnetic moment of the recently observed $Θ^+$ pentaquark in the framework of the light cone QCD sum rules using the photon distribution amplitudes. We find that $μ_{Θ^+}=(0.12\pm 0.06) μ_N$, which is quite small. We also compare our result with predictions of other groups.