Abstract The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU（3） quark model, where Q is the heavy quark （c or b） and q is the light quark （u, d, or s）. We obt...Abstract The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU（3） quark model, where Q is the heavy quark （c or b） and q is the light quark （u, d, or s）. We obtain a bound state for the bbnn configuration with quantum number JR=1^＋, I = 0 and for the ccnn （JR=1^＋, I=O） configuration, which is not bound but slightly above the D^＊ D^＊ threshold （n is u or d quark）. Meanwhile, we also conclude that a weakly bound state in bbnn system can also be found without considering the ehiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.展开更多
By differentiating the dressed quark propagator with respect to a variable background field, the linear response of the dressed quark propagator in the presence of the background field can be obtained. From this gener...By differentiating the dressed quark propagator with respect to a variable background field, the linear response of the dressed quark propagator in the presence of the background field can be obtained. From this general method, using the vector background tield as an illustration, we extract a general formula for the four-quark condensate （0： q（0）γμq（0）q（0）γμq（0） ： ｜0）. This formula contains the corresponding fully dressed vector vertex. We use this formula to analyze the factorization problem of the four-quark condensate and show that in the bare vertex approximation factorization holds exactly.展开更多
The relations among four-quark states, diquarks and QCD sum rules are discussed. The situation of the existing, but incomplete studies of four-quark states with QCD sum rules is analyzed. Masses of some diquark cluste...The relations among four-quark states, diquarks and QCD sum rules are discussed. The situation of the existing, but incomplete studies of four-quark states with QCD sum rules is analyzed. Masses of some diquark clusters were attempted to be determined by QCD sum rules, and masses of some light tetraquark states were obtained in terms of the diquarks.展开更多
The new members of the charm-strange family Dsj^＊（2317）, Dsj（2460）, and Ds（2632）, which have the surprising properties, are challenging the present models. Many theoretical interpretations have been devoted to ...The new members of the charm-strange family Dsj^＊（2317）, Dsj（2460）, and Ds（2632）, which have the surprising properties, are challenging the present models. Many theoretical interpretations have been devoted to this issue. Most authors suggest that they are not the conventional cs^- quark model states, but possibly are four-quark states, molecule states, or mixtures of a P-wave cs^- and a four-quark state. In this work, we follow the four-quark-state picture, and study the masses of cnn^-s^-/css^-s^- states （n is u or d quark） in the chiral SU（3） quark model. The numerical results show that the mass of the mixed four-quark state （cnn^-s^-/css^-s^-） with spin parity j^P ： 0^＋ might not be Ds （2632）. At the same time, we also conclude that Dsj^＊（2317） and Dsj（2460） cannot be explained as the pure four-quark state.展开更多
The surprising thing is that arising almost 50 years ago from the linear sigma model （LSM） with spontaneously broken chiral symmetry, the light scalar meson problem has become central in the nonperturbative quantum ...The surprising thing is that arising almost 50 years ago from the linear sigma model （LSM） with spontaneously broken chiral symmetry, the light scalar meson problem has become central in the nonperturbative quantum chromodynamics （QCD） for it has been made clear that LSM could be the low energy realization of QCD. First we review briefly signs of four-quark nature of light scalars. Then we show that the light scalars are produced in the two photon collisions via four-quark transitions in contrast to the classic P wave tensor qq mesons that are produced via two-quark transitions γγ→qq. Thus we get new evidence of the four-quark nature of these states.展开更多
We study QQqq and QqQq states as mixed states in QCD sum rules.By calculating the two-point correlation functions of pure states of their corresponding currents,we review the mass and coupling constant predictions of ...We study QQqq and QqQq states as mixed states in QCD sum rules.By calculating the two-point correlation functions of pure states of their corresponding currents,we review the mass and coupling constant predictions of J^(PC)=1^(++),1^(--),and 1^(-+)states.By calculating the two-point mixed correlation functions of QQqq and QqQq currents,we estimate the mass and coupling constants of the corresponding"physical state"that couples to both QQqq and QqQq currents.Our results suggest that for 1^(++)states,the QQqq and QqQq components are more likely to mix,while for 1^(--)and 1^(-+)states,there is less mixing between QQqq and QqQq.Our results suggest the Y series of states have more complicated components.展开更多
Open-flavor strong decays are studied based on the interaction of a potential quark model. The decay process is related to the s-channel contribution of the same scalar confinement and one-gluon-exchange （OGE） inter...Open-flavor strong decays are studied based on the interaction of a potential quark model. The decay process is related to the s-channel contribution of the same scalar confinement and one-gluon-exchange （OGE） interaction in the quark model. After we adopt the prescription of massive gluons in a 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 and s light flavor sectors. The analysis of the DIS ratios of b1 →ωπ and a1 → ρπ shows that the scalar interaction should be dominant in the open-flavor decays.展开更多
We study the fine splitting in the charmomium spectrum in the quark model with the channel coupling effect, including DD, DD＊, D＊D＊ and DsDs, DsDs＊, Ds＊Ds＊ channels. The interaction for channel coupling is const...We study the fine splitting in the charmomium spectrum in the quark model with the channel coupling effect, including DD, DD＊, D＊D＊ and DsDs, DsDs＊, Ds＊Ds＊ channels. The interaction for channel coupling is constructed from the current-current Lagrangian related to the color confinement and the onegluon exchange potentials. By adopting the massive gluon propagator from the lattice cMculation in the nonperturbative region, the coupling interaction is further simplified to four-fermion interaction. The numerical calculation still prefers the assignment 1＋＋ of X（3872）.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant Nos.10475087 and 10775146
文摘Abstract The possibility of QQqq heavy-light four-quark bound states has been analyzed by means of the chiral SU（3） quark model, where Q is the heavy quark （c or b） and q is the light quark （u, d, or s）. We obtain a bound state for the bbnn configuration with quantum number JR=1^＋, I = 0 and for the ccnn （JR=1^＋, I=O） configuration, which is not bound but slightly above the D^＊ D^＊ threshold （n is u or d quark）. Meanwhile, we also conclude that a weakly bound state in bbnn system can also be found without considering the ehiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 10175033, 10135030, and 10575050 and the Research Fund for the Doctoral Program of Higher Education under Grant No. 20030284009
文摘By differentiating the dressed quark propagator with respect to a variable background field, the linear response of the dressed quark propagator in the presence of the background field can be obtained. From this general method, using the vector background tield as an illustration, we extract a general formula for the four-quark condensate （0： q（0）γμq（0）q（0）γμq（0） ： ｜0）. This formula contains the corresponding fully dressed vector vertex. We use this formula to analyze the factorization problem of the four-quark condensate and show that in the bare vertex approximation factorization holds exactly.
基金Supported by National Natural Science Foundation of China (10775093)
文摘The relations among four-quark states, diquarks and QCD sum rules are discussed. The situation of the existing, but incomplete studies of four-quark states with QCD sum rules is analyzed. Masses of some diquark clusters were attempted to be determined by QCD sum rules, and masses of some light tetraquark states were obtained in terms of the diquarks.
基金National Natural Science Foundation of China under Grant No 10475087
文摘The new members of the charm-strange family Dsj^＊（2317）, Dsj（2460）, and Ds（2632）, which have the surprising properties, are challenging the present models. Many theoretical interpretations have been devoted to this issue. Most authors suggest that they are not the conventional cs^- quark model states, but possibly are four-quark states, molecule states, or mixtures of a P-wave cs^- and a four-quark state. In this work, we follow the four-quark-state picture, and study the masses of cnn^-s^-/css^-s^- states （n is u or d quark） in the chiral SU（3） quark model. The numerical results show that the mass of the mixed four-quark state （cnn^-s^-/css^-s^-） with spin parity j^P ： 0^＋ might not be Ds （2632）. At the same time, we also conclude that Dsj^＊（2317） and Dsj（2460） cannot be explained as the pure four-quark state.
基金Supported by RFFI Grant No.07-02-00093 from the Russian Foundation for Basic ResearchPresidential Grant No.NSh-1027.2008.2 for Leading Scientific Schools
文摘The surprising thing is that arising almost 50 years ago from the linear sigma model （LSM） with spontaneously broken chiral symmetry, the light scalar meson problem has become central in the nonperturbative quantum chromodynamics （QCD） for it has been made clear that LSM could be the low energy realization of QCD. First we review briefly signs of four-quark nature of light scalars. Then we show that the light scalars are produced in the two photon collisions via four-quark transitions in contrast to the classic P wave tensor qq mesons that are produced via two-quark transitions γγ→qq. Thus we get new evidence of the four-quark nature of these states.
基金Supported by NSFC(11175153,11205093)the Natural Sciences and Engineering Research Council of Canada(NSERC)。
文摘We study QQqq and QqQq states as mixed states in QCD sum rules.By calculating the two-point correlation functions of pure states of their corresponding currents,we review the mass and coupling constant predictions of J^(PC)=1^(++),1^(--),and 1^(-+)states.By calculating the two-point mixed correlation functions of QQqq and QqQq currents,we estimate the mass and coupling constants of the corresponding"physical state"that couples to both QQqq and QqQq currents.Our results suggest that for 1^(++)states,the QQqq and QqQq components are more likely to mix,while for 1^(--)and 1^(-+)states,there is less mixing between QQqq and QqQq.Our results suggest the Y series of states have more complicated components.
文摘Open-flavor strong decays are studied based on the interaction of a potential quark model. The decay process is related to the s-channel contribution of the same scalar confinement and one-gluon-exchange （OGE） interaction in the quark model. After we adopt the prescription of massive gluons in a 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 and s light flavor sectors. The analysis of the DIS ratios of b1 →ωπ and a1 → ρπ shows that the scalar interaction should be dominant in the open-flavor decays.
基金Supported by National Natural Science Foundation of China (10675008)
文摘We study the fine splitting in the charmomium spectrum in the quark model with the channel coupling effect, including DD, DD＊, D＊D＊ and DsDs, DsDs＊, Ds＊Ds＊ channels. The interaction for channel coupling is constructed from the current-current Lagrangian related to the color confinement and the onegluon exchange potentials. By adopting the massive gluon propagator from the lattice cMculation in the nonperturbative region, the coupling interaction is further simplified to four-fermion interaction. The numerical calculation still prefers the assignment 1＋＋ of X（3872）.
