In this work, we study the contributions of non-spectator effects to the lifetimes of Λb and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive ...In this work, we study the contributions of non-spectator effects to the lifetimes of Λb and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive the formulation of the non-spectator effects at the quark level. Especially, for Λb we have considered two pictures: the three-valence-quark picture and the quark-diquark picture. In the two pictures, the interference contributions to the total width are different, in this work, we investigate the interference effects in detail. As a preliminary estimate on the lifetimes, we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of a simple phenomenological model for both pictures. Our results show that the contributions of the non-spectator effects can reduce the ratio of lifetime of Λb to that of B-mesons by 5 ～ 7%. It is noted that in the quark-diquark picture the ratio can be further reduced if excited states of the diquark system are taken into account. We conclude that the measured ratio τ(Λb)/τ(B0)(≈)0.79 [The Data Group, Phys. Rev. D66 (2002) 010001] can be partly understood by the non-spectator effects, although the problem on the discrepancy between theoretical prediction and experimental measurement is not fully solved.展开更多
The newly observed D^＊aj family containing D^＊aj（2317）, Daj（2460）, and Daj（2632） attracts great interests. Determining their structures may be an important task for both theorists and experimentalists. In this...The newly observed D^＊aj family containing D^＊aj（2317）, Daj（2460）, and Daj（2632） attracts great interests. Determining their structures may be an important task for both theorists and experimentalists. In this work we use a non-relativistic model （the harmonic oscillator model） to evaluate the production rate of D^＊aj （2317） from the decays of ψ（4415）. For a comparison, we a/so employ the widely adopted heavy quark effective theory to repeat the calculation. We lind that the rate is sizable and may be observed at BES III and CLEO, if it is a p-wave excited state of Da（1968）. Unfortunately, the other two members of the family cannot be observed through decays of charmonia, because of the constraints from the final state phase space.展开更多
We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the qua...We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.展开更多
A method for obtaining the small current quark mass dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach the small current quark mass effects on...A method for obtaining the small current quark mass dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach the small current quark mass effects on dressed-quark propagator have been studied. A comparison with previous results is given.展开更多
Based on the global color symmetry mode/ （GCM）, a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator c...Based on the global color symmetry mode/ （GCM）, a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one shouM use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.展开更多
We calculate the new physics contributions to the neutral Bd^o and Ba^o meson mass splitting △Md and △Ma induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model （T2HD...We calculate the new physics contributions to the neutral Bd^o and Ba^o meson mass splitting △Md and △Ma induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model （T2HDM）. Using the precision data, we obtain the bounds on the parameter space of the T2HDM： （a） For fixed MH = 400 GeV and 5= [0°, 60°], the upper bound on tan β is tan β≤ 30 after the inclusion of major theoretical uncertainties; （b） For the case of tan β≤ 20, a light charged Higgs boson with a mass around 300 GeV is allowed; and （c） The bounds on tan β and MH are strongly correlated： a smaller （larger） tan β means a lighter （heavier） charged Higgs boson.展开更多
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.
As a sister work of[Phys. Rev. D 79 （2009） 094004], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potent...As a sister work of[Phys. Rev. D 79 （2009） 094004], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of bottomonimn. We calculate the masses, electromagnetic decays, and E1 transitions of bottomonium states. We find that the fine splittings between χbJ （J = 0, 1, 2） states are in good agreement with experimental data, and the E1 transition rates of γ（2S） → γχbJ（1P） and γ（3S） →γχbJ（2P） （J = 0, 1, 2） all agree with data within experimental errors. In particular, the mass of γ（6S） is lowered down to match that of the γ（11020）, which is smaller than the predictions of the linear potential models by more than 100 MeV. Comparison between charmonium and bottomonium in some related problems is also discussed.展开更多
文摘In this work, we study the contributions of non-spectator effects to the lifetimes of Λb and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive the formulation of the non-spectator effects at the quark level. Especially, for Λb we have considered two pictures: the three-valence-quark picture and the quark-diquark picture. In the two pictures, the interference contributions to the total width are different, in this work, we investigate the interference effects in detail. As a preliminary estimate on the lifetimes, we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of a simple phenomenological model for both pictures. Our results show that the contributions of the non-spectator effects can reduce the ratio of lifetime of Λb to that of B-mesons by 5 ～ 7%. It is noted that in the quark-diquark picture the ratio can be further reduced if excited states of the diquark system are taken into account. We conclude that the measured ratio τ(Λb)/τ(B0)(≈)0.79 [The Data Group, Phys. Rev. D66 (2002) 010001] can be partly understood by the non-spectator effects, although the problem on the discrepancy between theoretical prediction and experimental measurement is not fully solved.
基金The project supported by National Natural Science Foundation of China and the Special Research Fund for Doctor Programs of the Chinese Universities
文摘The newly observed D^＊aj family containing D^＊aj（2317）, Daj（2460）, and Daj（2632） attracts great interests. Determining their structures may be an important task for both theorists and experimentalists. In this work we use a non-relativistic model （the harmonic oscillator model） to evaluate the production rate of D^＊aj （2317） from the decays of ψ（4415）. For a comparison, we a/so employ the widely adopted heavy quark effective theory to repeat the calculation. We lind that the rate is sizable and may be observed at BES III and CLEO, if it is a p-wave excited state of Da（1968）. Unfortunately, the other two members of the family cannot be observed through decays of charmonia, because of the constraints from the final state phase space.
文摘We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the NN- in S-wave (the quarks in the nucleons N and N-, and the two nucleons relatively as well, are in S wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of pp- in J/ψ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight S-wave bound state of six quarks, then the quantum number of the bound state is very likely to be I = 1, JPC= 0-+.
文摘A method for obtaining the small current quark mass dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach the small current quark mass effects on dressed-quark propagator have been studied. A comparison with previous results is given.
基金The project supported in part by National Natural Science Foundation of China under Grant Nos. 10575050 and 10135030 and the Research Fund for the Doctoral Program of Higher Education under Grant No. 20030284009.
文摘Based on the global color symmetry mode/ （GCM）, a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one shouM use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.
基金The project partly supported by National Natural Science Foundation of China under Grant No. 10575052 and the Specialized Research Fund for the Doctoral Program of Higher Education （SRFDP） under Grant No. 20050319008.Acknowledgments 0ne of the authors Lin-Xia Lü would like to thank Prof. C.S. Huang for his valuable help.
文摘We calculate the new physics contributions to the neutral Bd^o and Ba^o meson mass splitting △Md and △Ma induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model （T2HDM）. Using the precision data, we obtain the bounds on the parameter space of the T2HDM： （a） For fixed MH = 400 GeV and 5= [0°, 60°], the upper bound on tan β is tan β≤ 30 after the inclusion of major theoretical uncertainties; （b） For the case of tan β≤ 20, a light charged Higgs boson with a mass around 300 GeV is allowed; and （c） The bounds on tan β and MH are strongly correlated： a smaller （larger） tan β means a lighter （heavier） charged Higgs boson.
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 in part by the National Natural Science Foundation of China under Grant Nos.10675003 and 10721063the Ministry of Science and Technology of China under Grant No.2009CB825200
文摘As a sister work of[Phys. Rev. D 79 （2009） 094004], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of bottomonimn. We calculate the masses, electromagnetic decays, and E1 transitions of bottomonium states. We find that the fine splittings between χbJ （J = 0, 1, 2） states are in good agreement with experimental data, and the E1 transition rates of γ（2S） → γχbJ（1P） and γ（3S） →γχbJ（2P） （J = 0, 1, 2） all agree with data within experimental errors. In particular, the mass of γ（6S） is lowered down to match that of the γ（11020）, which is smaller than the predictions of the linear potential models by more than 100 MeV. Comparison between charmonium and bottomonium in some related problems is also discussed.
