In this article, we study the structures of the pseudoscalar mesons π, K and the scalar diquarks U^a, D^a, Sa in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with t...In this article, we study the structures of the pseudoscalar mesons π, K and the scalar diquarks U^a, D^a, Sa in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with the confining effective potential. The u, d, s quarks have small current masses, and the renormalization is very large, the mass poles in the timelike region are absent which implements confinement naturally. The Bethe-Salpeter wavefunctions of the pseudoscalar mesons π, K, and the scalar diquarks U^a, D^a, S^a have the same type （Gaussian type） momentum dependence, center around zero momentum and extend to the energy scale about q^2 = 1 GeV^2, which happens to be the energy scale for the chiral symmetry breaking, the strong interactions in the infrargd region result in bound （or quasl-bound） states. The numerical results for the masses and decay constants of the π and K mesons can reproduce the experimental values, and the ground state masses of the scalar diquarks U^a, D^a, S^a are consistent with the existing theoretical calculations. We suggest a new Lagrangian which may explain the uncertainty of the masses of the scalar diauarks.展开更多
In this article, we study the light-flavor scalar and a^ial-vector diquark states in the vacuum and in the nuclear matter using the QCD sum rules in a systematic way, and make reasonable predictions for their masses i...In this article, we study the light-flavor scalar and a^ial-vector diquark states in the vacuum and in the nuclear matter using the QCD sum rules in a systematic way, and make reasonable predictions for their masses in the vacuum and in the nuclear matter.展开更多
In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansi...In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value M_X =(5.57 ± 0.12) Ge V, which is consistent with the experimental data. The present prediction favors assigning the X(5568) to be the scalar tetraquark state.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No. 10405009 The authors are indebted to Dr： J. He （IHEP）, Dr. X.B. nuang （PKU） and Dr. L. Li （GSCAS） for numerous help. Without them, the work would not be finished. The authors would also like to thank Prof. C.D. Roberts for providing us some important literatures.
文摘In this article, we study the structures of the pseudoscalar mesons π, K and the scalar diquarks U^a, D^a, Sa in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with the confining effective potential. The u, d, s quarks have small current masses, and the renormalization is very large, the mass poles in the timelike region are absent which implements confinement naturally. The Bethe-Salpeter wavefunctions of the pseudoscalar mesons π, K, and the scalar diquarks U^a, D^a, S^a have the same type （Gaussian type） momentum dependence, center around zero momentum and extend to the energy scale about q^2 = 1 GeV^2, which happens to be the energy scale for the chiral symmetry breaking, the strong interactions in the infrargd region result in bound （or quasl-bound） states. The numerical results for the masses and decay constants of the π and K mesons can reproduce the experimental values, and the ground state masses of the scalar diquarks U^a, D^a, S^a are consistent with the existing theoretical calculations. We suggest a new Lagrangian which may explain the uncertainty of the masses of the scalar diauarks.
基金Supported by National Natural Science Foundation of China under Grant No.11075053the Fundamental Research Funds for the Central Universities
文摘In this article, we study the light-flavor scalar and a^ial-vector diquark states in the vacuum and in the nuclear matter using the QCD sum rules in a systematic way, and make reasonable predictions for their masses in the vacuum and in the nuclear matter.
基金Supported by National Natural Science Foundation under Grant No.11375063Natural Science Foundation of Hebei Province under Grant No.A2014502017
文摘In this article, we take the X(5568) as the diquark-antidiquark type tetraquark state with the spin-parity J^P= 0^+, construct the scalar-diquark-scalar-antidiquark type current, carry out the operator product expansion up to the vacuum condensates of dimension-10, and study the mass and pole residue in details with the QCD sum rules. We obtain the value M_X =(5.57 ± 0.12) Ge V, which is consistent with the experimental data. The present prediction favors assigning the X(5568) to be the scalar tetraquark state.
