The low-lying sQq¯q¯ (q=u, d, Q=c, b) tetraquark states with JP=0+, 1+, and 2+, and in the isoscalar and isovector sectors, are systematically investigated in the framework of the real- and complex-scaling r...
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The low-lying sQq¯q¯ (q=u, d, Q=c, b) tetraquark states with JP=0+, 1+, and 2+, and in the isoscalar and isovector sectors, are systematically investigated in the framework of the real- and complex-scaling range of a chiral quark model, whose parameters are fixed in advance describing hadron, hadron-hadron, and multiquark phenomenology, and thus, all results presented here are pure predictions. Each tetraquark configuration compatible with the quantum numbers studied is taken into account; this includes meson-meson, diquark-antidiquark, and K-type arrangements of quarks with all possible color wave functions in the four-body sector. Among the different numerical techniques to solve the Schrödinger-like four-body bound-state equation, we use a variational method in which the trial wave function is expanded in complex-range Gaussian basis functions because of its simplicity and flexibility. Several compact bound states and narrow resonances are found in both charm-strange csq¯q¯ and bottom-strange bsq¯q¯ tetraquark sectors, most of them as a product of the strong coupling between the different channels. In regard to the so-called X0,1(2900) structures recently discovered with good statistical significance by the LHCb Collaboration, whose properties point out to be csu¯d¯ tetraquarks, we find that they are unstable in our formalism with several candidates in the single-channel computations. We distinguish four cases with I(JP)=0(0+) quantum numbers: three K-type configurations with masses at 2.89, 2.96, and 2.97 GeV, and one hidden-color coupled-channel calculation delivering a mass 2.86 GeV. With quantum numbers I(JP)=0(1+), only one candidate can be found in the hidden-color coupled-channel calculation with mass 2.94 GeV.
In this paper, a class of arbitrarily high-order linear momentum-preserving and energy-preserving schemes are proposed, respectively, for solving the regularized long-wave equation. For the momentum-preserving scheme,...
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Inspired by the recent observation of exotic resonances X(4140), X(4274), X(4350), X(4500), and X(4700) reported by several experiment collaborations, we investigated the four-quark system csc¯s¯ with quantu...
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Inspired by the recent observation of exotic resonances X(4140), X(4274), X(4350), X(4500), and X(4700) reported by several experiment collaborations, we investigated the four-quark system csc¯s¯ with quantum numbers JPC=1++ and 0++ in the framework of the chiral quark model. Two configurations, diquark-antidiquark and meson-meson, with all possible color structures are considered. The results show that no molecular state can be formed, but the resonance may exist if the color structure of the meson-meson configuration is 8⊗8. In the present calculation, the X(4274) can be assigned as the csc¯s¯ tetraquark states with JPC=1++, but the energy of X(4140) is too low to be regarded as the tetraquark state. X(4350) can be a good candidate of the compact tetraquark state with JPC=0++. When the radial excitation is taken into account, the X(4700) can be explained as the 2S radial excited tetraquark state with JPC=0++. As for X(4500), there is no matching state in our calculation.
In this paper we calculate the mass and probability fractions of the meson-meson components of X(3872) in an unquenched quark model. Different from most other unquenched quark models, the quark-pair creation operator ...
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In this paper we calculate the mass and probability fractions of the meson-meson components of X(3872) in an unquenched quark model. Different from most other unquenched quark models, the quark-pair creation operator from P03 is modified by considering the effects of the created quark pair’s energy and the separation between the created quark pair and the valence quark pair. In the calculation all of the wave functions of the mesons and the relative motion between two mesons are obtained by solving the corresponding Schrödinger equation with the help of the Gaussian expansion method. The multichannel couplings of the quark-antiquark state with possible meson-meson states are calculated. The results show that X(3872) can be described as a mixing state of the dominant charmonium state (70%) and meson-meson components (30%).
A dynamical calculation of pentaquark systems with quark contents uudds¯ is performed in the framework of quark delocalization color screening model with the help of resonating group method. The effective potenti...
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A dynamical calculation of pentaquark systems with quark contents uudds¯ is performed in the framework of a quark delocalization color screening model with the help of the resonating group method. The effective p...
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A dynamical calculation of pentaquark systems with quark contents uudds¯ is performed in the framework of a quark delocalization color screening model with the help of the resonating group method. The effective potentials between baryon and meson clusters are given, and the possible bound states or resonances are investigated. The single calculations show that the NK* with I=0,JP=12−,ΔK* with I=1,JP=12−, and ΔK* with I=2,JP=32− are all bound, but they all turn into scattering states by coupling with the corresponding open channels. A possible resonance state ΔK* with I=1,JP=52− is proposed. The mass is around 2110.5 MeV, and the decay modes are NK in D wave and NKππ in P waves.
作者：
Tan, YuePing, JialunDepartment of Physics
Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China
In this paper, we calculate mass and probability fractions of meson-meson components of X(3872) in an unquenched quark model. Different from most of other unquenched quark models, the quark pairs creation operator fro...
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作者：
Tan, YuePing, JialunDepartment of Physics
Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China
Recently, Belle Collaboration reported a new exotic state Y (4620) with mass at 4625.9 MeV in the positronium annihilation process. Inspired by experiment, we study the tetraquark system css ¯ c¯ with quantu...
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We present a new temporal discretization paradigm for developing energy-production-rate preserving numerical approximations to thermodynamically consistent partial differential equation systems, called the supplementa...
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In this paper, we studied systematically the semileptonic decays B s ⟶ ϕ l + l − with l − = ( e − , μ − , τ − ) by using the perturbative QCD (PQCD) and the “PQCD+Lattice” factorization approach, respectively. We ...
In this paper, we studied systematically the semileptonic decays B s ⟶ ϕ l + l − with l − = ( e − , μ − , τ − ) by using the perturbative QCD (PQCD) and the “PQCD+Lattice” factorization approach, respectively. We first evaluated all relevant form factors F i ( q 2 ) in the low- q 2 region using the PQCD approach, and we also took the available lattice QCD results at the high- q 2 region as additional input to improve the extrapolation of F i ( q 2 ) from the low- q 2 region to the endpoint . We then calculated the branching ratios and many other physical observables , , S 3,4,7 , and A 5,6,8,9 and the clean angular observables P 1,2,3 and . From our studies, we find the following points: (a) the PQCD and “PQCD+Lattice” predictions of are about 7 × 10 −7 , which agree well with the LHCb measured values and the QCD sum rule prediction within still large errors; (b) we defined and calculated the ratios of the branching ratios and ; (c) the PQCD and “PQCD+Lattice” predictions of the longitudinal polarization F L , the CP-averaged angular coefficients S 3,4,7 , and the CP asymmetry angular coefficients A 5,6,8,9 agree with the LHCb measurements in all considered bins within the still large experimental errors; and (d) for those currently still unknown observables , and , we suggest LHCb and Belle-II Collaboration to measure them in their experiments.
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