Bound states, such as qq and q^-q, may exist the volume of the bound states may evoke a reduction in investigate qualitatively the volume effect on the properties states start to be completely melted.
The QCD sum rule approach is used to analyze the nature of the recently observed new resonance X （4350）, which is assumed to be a diquark-antidiquark state [cs][cs] with jPC = 1-＋. The interpolating current represe...The QCD sum rule approach is used to analyze the nature of the recently observed new resonance X （4350）, which is assumed to be a diquark-antidiquark state [cs][cs] with jPC = 1-＋. The interpolating current representing this state is proposed. In the calculation, contributions of operators up to dimension six are included in the operator product expansion （OPE）, as well as terms which are linear in the strange quark mass ms. We find ml-＋ = （4.82 ~ 0.19） GeV, which is not compatible with the X（4350） structure as a 1-＋ tetraquark state. Finally, we also discuss the difference of a four-quark state＇s mass whether the state＇s interpolating current has a definite charge conjugation.展开更多
In this work, we employ the Bethe-Salpeter （B-S） equation to investigate the spectra of free diquarks and their B-S wave functions. We find that the B-S approach can be consistently applied to study the diqaurks wit...In this work, we employ the Bethe-Salpeter （B-S） equation to investigate the spectra of free diquarks and their B-S wave functions. We find that the B-S approach can be consistently applied to study the diqaurks with two heavy quarks or one heavy and one light quarks, but for two light-quark systems, the results are not reliable. There are a few free parameters in the whole scenario which can only be fixed phenomenologically. Thus, to determine them, one has to study baryons which are composed of quarks and diquarks.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
In this article, we test the nature of X（3872）, which is assumed to be a P-wave [cq]-scalar-diquark [cq]- axial-vector-antidiquark tetraquark state with JP = 2^-. The interpolating current representing the JP = 2^- ...In this article, we test the nature of X（3872）, which is assumed to be a P-wave [cq]-scalar-diquark [cq]- axial-vector-antidiquark tetraquark state with JP = 2^-. The interpolating current representing the JP = 2^- state is proposed. Technically, contributions of the operators up to dimension six are included in the operator product expansion. The mass obtained for such state is m2- = （4.38±0.15） GeV. We conclude that it is impossible to describe the X（3872） structure as JV = 2^- tetraauark state.展开更多
In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in deta...In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula μ = √M^2X/ Y /Z-（2Mc）^2 to determine the energy scales of the QCD spectral densities. The predictions MJ =2=（4.02-0.09^＋0.09） GeV, MJ =1=（4.02-0.08^＋0.07） GeV favor assigning the Zc（4020） and Zc（4025） as the J^PC= 1^＋-or 2^＋＋diquark-antidiquark type tetraquark states, while the prediction MJ =0=（3.85-0.09^＋0.15） GeV disfavors assigning the Z（4050） and Z（4250） as the J^P C= 0^＋＋ diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0^＋＋, 1^＋-, 2^＋＋diquark-antidiquark type tetraquark states in details.展开更多
The effective potential analysis indicates that, in a 3D two-flavor Gross-Neveu model in vacuum, depending on whether Gs/Hp is less or bigger than the critical value 2/3, where G s and H p are respectively the couplin...The effective potential analysis indicates that, in a 3D two-flavor Gross-Neveu model in vacuum, depending on whether Gs/Hp is less or bigger than the critical value 2/3, where G s and H p are respectively the coupling constants of scalar quark-antiquark channel and pseudoscalar diquark channel, the system will have the ground state with pure diquark condensates or with pure quark-antiquark condensates, but never with coexistence of the two forms of condensates. The similarities and differences in the interplay between the quark-antiquark and the diquark condensates in vacuum in the 2D, 3D and 4D two-flavor four-fermion interaction models are summarized.展开更多
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 90103019 and 10428510.We thank professor Yu-Xin Liu for useful discussions,
文摘Bound states, such as qq and q^-q, may exist the volume of the bound states may evoke a reduction in investigate qualitatively the volume effect on the properties states start to be completely melted.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11347174,11275268,11105222,and 11025242
文摘The QCD sum rule approach is used to analyze the nature of the recently observed new resonance X （4350）, which is assumed to be a diquark-antidiquark state [cs][cs] with jPC = 1-＋. The interpolating current representing this state is proposed. In the calculation, contributions of operators up to dimension six are included in the operator product expansion （OPE）, as well as terms which are linear in the strange quark mass ms. We find ml-＋ = （4.82 ~ 0.19） GeV, which is not compatible with the X（4350） structure as a 1-＋ tetraquark state. Finally, we also discuss the difference of a four-quark state＇s mass whether the state＇s interpolating current has a definite charge conjugation.
基金The project partly supported by National Natural Science Foundation of China and the Special Fund for the Doctorate Programs of Universities. We highly benefit from discussions with Prof. C.H. Chang, who kindly introduces their new methods for numerically solving the B-S equation to us and indicates some important physics problems which we did not notice.
文摘In this work, we employ the Bethe-Salpeter （B-S） equation to investigate the spectra of free diquarks and their B-S wave functions. We find that the B-S approach can be consistently applied to study the diqaurks with two heavy quarks or one heavy and one light quarks, but for two light-quark systems, the results are not reliable. There are a few free parameters in the whole scenario which can only be fixed phenomenologically. Thus, to determine them, one has to study baryons which are composed of quarks and diquarks.
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.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10975184,11047117,11105222,and 11105223
文摘In this article, we test the nature of X（3872）, which is assumed to be a P-wave [cq]-scalar-diquark [cq]- axial-vector-antidiquark tetraquark state with JP = 2^-. The interpolating current representing the JP = 2^- state is proposed. Technically, contributions of the operators up to dimension six are included in the operator product expansion. The mass obtained for such state is m2- = （4.38±0.15） GeV. We conclude that it is impossible to describe the X（3872） structure as JV = 2^- tetraauark state.
基金Supported by National Natural Science Foundation of China under Grant No.11375063Natural Science Foundation of Hebei Province under Grant No.A2014502017
文摘In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the C γμ- Cγνtype scalar, axial-vector and tensor tetraquark states in details with the QCD sum rules. In calculations, we use the formula μ = √M^2X/ Y /Z-（2Mc）^2 to determine the energy scales of the QCD spectral densities. The predictions MJ =2=（4.02-0.09^＋0.09） GeV, MJ =1=（4.02-0.08^＋0.07） GeV favor assigning the Zc（4020） and Zc（4025） as the J^PC= 1^＋-or 2^＋＋diquark-antidiquark type tetraquark states, while the prediction MJ =0=（3.85-0.09^＋0.15） GeV disfavors assigning the Z（4050） and Z（4250） as the J^P C= 0^＋＋ diquark-antidiquark type tetraquark states. Furthermore, we discuss the strong decays of the 0^＋＋, 1^＋-, 2^＋＋diquark-antidiquark type tetraquark states in details.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475113
文摘The effective potential analysis indicates that, in a 3D two-flavor Gross-Neveu model in vacuum, depending on whether Gs/Hp is less or bigger than the critical value 2/3, where G s and H p are respectively the coupling constants of scalar quark-antiquark channel and pseudoscalar diquark channel, the system will have the ground state with pure diquark condensates or with pure quark-antiquark condensates, but never with coexistence of the two forms of condensates. The similarities and differences in the interplay between the quark-antiquark and the diquark condensates in vacuum in the 2D, 3D and 4D two-flavor four-fermion interaction models are summarized.
