Recent anomalies observed in e^(+)e^(-)nuclear transitions of,^(8)Be,^(4)He,and^(12)C by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV,which is referred to as X17.If it...Recent anomalies observed in e^(+)e^(-)nuclear transitions of,^(8)Be,^(4)He,and^(12)C by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV,which is referred to as X17.If it exists,this boson would affect similar processes in particle physics,including the Dalitz decays of vector mesons.Recently,the BESIII collaboration measured the Dalitz decay D^(*0)→D^(0)e^(+)e^(-)for the first time and reported a excess over the theoretical prediction based on the vector meson dominance(VMD)model.This excess may be another signal of X17.In this study,we investigate the possible effects of X17 on the Dalitz decays,D_(s)^(*)→D_(s)e^(+)e^(-),B_(s)^(*)→B_(s)e^(+)e^(-),and J/ψ→η_(c)e^(+)e^(-).The required hadronic form factors are calculated within the framework of our covariant confined quark model without relying on heavy quark effective theory or the VMD model.We present predictions for the Dalitz decay widths and the ratios R_(ee)(V)≡Γ(V→Pe^(+)e^(-))/Γ(V→Pγ)within the standard model and in several new physics scenarios involving modifications attributed to X17.Our results are compared with other theoretical calculations.展开更多
We study the exclusive semileptonic decaysΥ(1S)→B_((c))lν_(l),where t=e,μ,t.The relevant hadronic form factors are calculated using the covariant confined quark model developed previously by our group.We predict t...We study the exclusive semileptonic decaysΥ(1S)→B_((c))lν_(l),where t=e,μ,t.The relevant hadronic form factors are calculated using the covariant confined quark model developed previously by our group.We predict the branching fractions B(Υ(1S)→B_((c))lν_(l))(vl)to be of the order of 10^(-13)and 10^(-10)for the case of B and B_(C),respectively.Our predictions agree well with other theoretical calculations.We also consider the effects of possible new physics in the case of Υ(1S)→B_((c))τν_(τ)and show that the branching fraction of this decay can be enhanced by an order of magnitude using constraints from the B-→D^((*))lν_(l)and B_(C)→J/Ψlν_(l)experimental data.展开更多
Radiative decays D((s))*→D((s))γare revisited in light of new experimental data from the BaBar and BESⅢCollaborations.The radiative couplings gD*Dγencoding nonperturbative QCD effects are calculated in the framewo...Radiative decays D((s))*→D((s))γare revisited in light of new experimental data from the BaBar and BESⅢCollaborations.The radiative couplings gD*Dγencoding nonperturbative QCD effects are calculated in the framework of the covariant confined quark model developed by us.We compare our results with other theoretical studies and experimental data.The couplings(in GeV-1)|g(D*+D+γ)|=0.45(9)and|g(D*0D0γ)|=1.72(34)calculated in our model agree with the corresponding experimental data|g(D*+D+γ)|=0.47(7)and|g(D*0D0γ)|=1.77(16).The most interesting case is the decay Ds*→Dsγ,for which a recent prediction based on light-cone sum rules at next-to-leading order|gDs*Dsγ|=0.60(19)deviates from the first(and only to date)lattice QCD result|gDs*Dsγ|=0.11(2)at nearly3σ.Our calculation yields|gDs*Dsγ|=0.29(6),which falls somehow between the two mentioned results,although it is larger than those predicted in other studies using quark models or QCD sum rules.展开更多
Recently,the BESⅢcollaboration has reported numerous measurements of various D(s)meson semileptonic decays with significantly improved precision.Together with similar studies carried out at BABAR,Belle,and CLEO,new w...Recently,the BESⅢcollaboration has reported numerous measurements of various D(s)meson semileptonic decays with significantly improved precision.Together with similar studies carried out at BABAR,Belle,and CLEO,new windows to a better understanding of weak and strong interactions in the charm sector have been opened.In light of new experimental data,we review the theoretical description and predictions for the semileptonic decays of D(s)to a pseudoscalar or a vector meson.This review is essentially an extended discussion of our recently published results obtained in the framework of the covariant confining quark model.展开更多
基金Supported by Ho Chi Minh City University of Technology and Education(T2024-65)。
文摘Recent anomalies observed in e^(+)e^(-)nuclear transitions of,^(8)Be,^(4)He,and^(12)C by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV,which is referred to as X17.If it exists,this boson would affect similar processes in particle physics,including the Dalitz decays of vector mesons.Recently,the BESIII collaboration measured the Dalitz decay D^(*0)→D^(0)e^(+)e^(-)for the first time and reported a excess over the theoretical prediction based on the vector meson dominance(VMD)model.This excess may be another signal of X17.In this study,we investigate the possible effects of X17 on the Dalitz decays,D_(s)^(*)→D_(s)e^(+)e^(-),B_(s)^(*)→B_(s)e^(+)e^(-),and J/ψ→η_(c)e^(+)e^(-).The required hadronic form factors are calculated within the framework of our covariant confined quark model without relying on heavy quark effective theory or the VMD model.We present predictions for the Dalitz decay widths and the ratios R_(ee)(V)≡Γ(V→Pe^(+)e^(-))/Γ(V→Pγ)within the standard model and in several new physics scenarios involving modifications attributed to X17.Our results are compared with other theoretical calculations.
基金Supported by Ho Chi Minh City University of Technology and Education under Grant T2023-76。
文摘We study the exclusive semileptonic decaysΥ(1S)→B_((c))lν_(l),where t=e,μ,t.The relevant hadronic form factors are calculated using the covariant confined quark model developed previously by our group.We predict the branching fractions B(Υ(1S)→B_((c))lν_(l))(vl)to be of the order of 10^(-13)and 10^(-10)for the case of B and B_(C),respectively.Our predictions agree well with other theoretical calculations.We also consider the effects of possible new physics in the case of Υ(1S)→B_((c))τν_(τ)and show that the branching fraction of this decay can be enhanced by an order of magnitude using constraints from the B-→D^((*))lν_(l)and B_(C)→J/Ψlν_(l)experimental data.
基金Supported by Ho Chi Minh City University of Technology and Education(T2022-26)。
文摘Radiative decays D((s))*→D((s))γare revisited in light of new experimental data from the BaBar and BESⅢCollaborations.The radiative couplings gD*Dγencoding nonperturbative QCD effects are calculated in the framework of the covariant confined quark model developed by us.We compare our results with other theoretical studies and experimental data.The couplings(in GeV-1)|g(D*+D+γ)|=0.45(9)and|g(D*0D0γ)|=1.72(34)calculated in our model agree with the corresponding experimental data|g(D*+D+γ)|=0.47(7)and|g(D*0D0γ)|=1.77(16).The most interesting case is the decay Ds*→Dsγ,for which a recent prediction based on light-cone sum rules at next-to-leading order|gDs*Dsγ|=0.60(19)deviates from the first(and only to date)lattice QCD result|gDs*Dsγ|=0.11(2)at nearly3σ.Our calculation yields|gDs*Dsγ|=0.29(6),which falls somehow between the two mentioned results,although it is larger than those predicted in other studies using quark models or QCD sum rules.
文摘Recently,the BESⅢcollaboration has reported numerous measurements of various D(s)meson semileptonic decays with significantly improved precision.Together with similar studies carried out at BABAR,Belle,and CLEO,new windows to a better understanding of weak and strong interactions in the charm sector have been opened.In light of new experimental data,we review the theoretical description and predictions for the semileptonic decays of D(s)to a pseudoscalar or a vector meson.This review is essentially an extended discussion of our recently published results obtained in the framework of the covariant confining quark model.
