Scientists in Beijing have observed the mixing of two light scalar mesons,a00(980)and f0(980),using data samples accumulated with the Beijing Spectrometer(BESIII).This observation may help clear up what the 980 MeV sc...Scientists in Beijing have observed the mixing of two light scalar mesons,a00(980)and f0(980),using data samples accumulated with the Beijing Spectrometer(BESIII).This observation may help clear up what the 980 MeV scalar mesons are made of(e.g.,a tetraquark,a meson molecule,or a quark-gluon hybrid).Although light scalar mesons a00(980)and f0(980)are well-established in experiment,explanations about their nature have been controversial for several decades.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
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
Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after...Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronlc gas model for nuclear matter. The relative yield ratio of tetraquark cs^-s^-s to Ω is less than 0.0164.展开更多
We investigated the neutral Higgs boson pair production at the CERN Large Hadron Collider (LHC) in the SM with four families. We found that the gluon-gluon fusion mode is the most dominant one in producing neutral Hig...We investigated the neutral Higgs boson pair production at the CERN Large Hadron Collider (LHC) in the SM with four families. We found that the gluon-gluon fusion mode is the most dominant one in producing neutral Higgs boson pair at the LHC, and it can be used to probe the trilinear Higgs coupling. If the heavy quarks of the fourth generation really exist within the SM, they can manifest their effect on the cross section of the Higgs pair production process at the LHC. Our numerical results show that there will be neutral Higgs boson pair production events per year if the next generation heavy quarks really exist, while there will be only events produced per year if there are only three families in the SM.展开更多
文摘Scientists in Beijing have observed the mixing of two light scalar mesons,a00(980)and f0(980),using data samples accumulated with the Beijing Spectrometer(BESIII).This observation may help clear up what the 980 MeV scalar mesons are made of(e.g.,a tetraquark,a meson molecule,or a quark-gluon hybrid).Although light scalar mesons a00(980)and f0(980)are well-established in experiment,explanations about their nature have been controversial for several decades.
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The project partly supported by National Natural Science Foundation of China under Grant Nos. 10225525 and 10055003 and the CAS Knowledge Innovation Project under Grant No. KJCX2-SW-N02.The authors would like to thank B.S. Zou for helpful discussions and valuable remarks.
文摘Tetraquarks can be produced in relativistic heavy-ion collision. The yield of this kind of tetraquarks can increase significantly soon as the formation of QGP after the collision. If there is no phase transition after collision, the upper bound of the production of this four-quark states can be estimated from the free hadronlc gas model for nuclear matter. The relative yield ratio of tetraquark cs^-s^-s to Ω is less than 0.0164.
基金The project supported in part by National Natural Science Foundation of China
文摘We investigated the neutral Higgs boson pair production at the CERN Large Hadron Collider (LHC) in the SM with four families. We found that the gluon-gluon fusion mode is the most dominant one in producing neutral Higgs boson pair at the LHC, and it can be used to probe the trilinear Higgs coupling. If the heavy quarks of the fourth generation really exist within the SM, they can manifest their effect on the cross section of the Higgs pair production process at the LHC. Our numerical results show that there will be neutral Higgs boson pair production events per year if the next generation heavy quarks really exist, while there will be only events produced per year if there are only three families in the SM.
