The SO(3) gauge extension of SM, which is proposed to present a successful explanation for the observedsmall masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO(3) triplet Maj...The SO(3) gauge extension of SM, which is proposed to present a successful explanation for the observedsmall masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO(3) triplet Majorananeutrinos and SU_L(2) double Higgs bosons.In this work we calculate branching ratios of the charged lepton flavorviolating decays l_I■_JV (V = γ, Z) induced by these Majorana neutrinos and Higgs bosons.We find that under themodel parameters constrained by experimental bounds on the decays Z→l_I■_J, the branching ratio of decays l_I→l_Jγcan be up to 10^(-10), which may be accessible at the future experiments.展开更多
We evaluate the spin-independent elastic dark matter-nucleon scattering cross section in the framework of the simple singlet fermionic dark matter extension of the standard model and constrain the model parameter spac...We evaluate the spin-independent elastic dark matter-nucleon scattering cross section in the framework of the simple singlet fermionic dark matter extension of the standard model and constrain the model parameter space with the following considerations:(i)new dark matter measurement,in which,apart from WMAP and CDMS,the results from the XENON experiment are also used in constraining the model;(ii)new fitted value of the quark fractions in nucleons,in which the updated value of fta from the recent lattice simulation is much smaller than the previous one and may reduce the scattering rate significantly;(iii)new dark matter annihilation channels,in which the scenario where top quark and Higgs pairs produced by dark matter annihilation was not included in the previous works.We find that unlike in the minimal supersymmetric standard model,the cross section is just reduced by a factor of about 1/4 and dark matter lighter than 100 GeV is not favored by the WMAP,CDMS and XENON experiments.展开更多
In models with vector-like quark doublets, the mass matrices of up and down type quarks are related.Precise diagonalization of the mass matrices has become an obstacle in numerical studies. In this work we first propo...In models with vector-like quark doublets, the mass matrices of up and down type quarks are related.Precise diagonalization of the mass matrices has become an obstacle in numerical studies. In this work we first propose a diagonalization method. As its application, in the Standard Model with one vector-like quark doublet we present the quark mass spectrum and Feynman rules for the calculation of B → X_sγ. We find that i) under the constraints of the CKM matrix measurements, the mass parameters in the bilinear term are constrained to a small value by the small deviation from unitarity; ii) compared with the fourth generation extension of the Standard Model, there is an enhancement to the B → X_sγ process in the contribution of vector-like quarks, resulting in a non-decoupling effect in such models.展开更多
Using the Bs meson wave function extracted from non-leptonic Bs decays, we reevaluate the rare decays Bs→l+l- γ,(l=e,μ) in the Standard Model, including two kinds of contributions from the magnetic-penguin operator...Using the Bs meson wave function extracted from non-leptonic Bs decays, we reevaluate the rare decays Bs→l+l- γ,(l=e,μ) in the Standard Model, including two kinds of contributions from the magnetic-penguin operator with virtual and real photons. We find that contributions to the exclusive decays from the magnetic-penguin operator b→sγ with real photons, which were regarded as negligible in the previous literature, are large and the branching ratios Bs→l+l-γ are enhanced by a factor of almost 2. With the predicted branching ratios of the order of 10-8, it is expected that these radiative dileptonic decays will be detected in LHC-b and B factories in the near future.展开更多
文摘The SO(3) gauge extension of SM, which is proposed to present a successful explanation for the observedsmall masses of neutrino and the nearly tri-bimaximal neutrino mixing, predicted the vector-like SO(3) triplet Majorananeutrinos and SU_L(2) double Higgs bosons.In this work we calculate branching ratios of the charged lepton flavorviolating decays l_I■_JV (V = γ, Z) induced by these Majorana neutrinos and Higgs bosons.We find that under themodel parameters constrained by experimental bounds on the decays Z→l_I■_J, the branching ratio of decays l_I→l_Jγcan be up to 10^(-10), which may be accessible at the future experiments.
基金Supported by the National Natural Science Foundation of China under Grant No 10875009 and Natural Science Foundation of Beijing under Grant No 1072001.
基金by the Natural Science Foundation of Beijing under Grant No 1072001.
文摘We evaluate the spin-independent elastic dark matter-nucleon scattering cross section in the framework of the simple singlet fermionic dark matter extension of the standard model and constrain the model parameter space with the following considerations:(i)new dark matter measurement,in which,apart from WMAP and CDMS,the results from the XENON experiment are also used in constraining the model;(ii)new fitted value of the quark fractions in nucleons,in which the updated value of fta from the recent lattice simulation is much smaller than the previous one and may reduce the scattering rate significantly;(iii)new dark matter annihilation channels,in which the scenario where top quark and Higgs pairs produced by dark matter annihilation was not included in the previous works.We find that unlike in the minimal supersymmetric standard model,the cross section is just reduced by a factor of about 1/4 and dark matter lighter than 100 GeV is not favored by the WMAP,CDMS and XENON experiments.
基金Supported by Natural Science Foundation of China(11375001)Talents Foundation of Education Department of Beijing
文摘In models with vector-like quark doublets, the mass matrices of up and down type quarks are related.Precise diagonalization of the mass matrices has become an obstacle in numerical studies. In this work we first propose a diagonalization method. As its application, in the Standard Model with one vector-like quark doublet we present the quark mass spectrum and Feynman rules for the calculation of B → X_sγ. We find that i) under the constraints of the CKM matrix measurements, the mass parameters in the bilinear term are constrained to a small value by the small deviation from unitarity; ii) compared with the fourth generation extension of the Standard Model, there is an enhancement to the B → X_sγ process in the contribution of vector-like quarks, resulting in a non-decoupling effect in such models.
基金Supported by National Natural Science Foundation of China(11005006,11172008)Ri Xin Foundation of BJUT
文摘Using the Bs meson wave function extracted from non-leptonic Bs decays, we reevaluate the rare decays Bs→l+l- γ,(l=e,μ) in the Standard Model, including two kinds of contributions from the magnetic-penguin operator with virtual and real photons. We find that contributions to the exclusive decays from the magnetic-penguin operator b→sγ with real photons, which were regarded as negligible in the previous literature, are large and the branching ratios Bs→l+l-γ are enhanced by a factor of almost 2. With the predicted branching ratios of the order of 10-8, it is expected that these radiative dileptonic decays will be detected in LHC-b and B factories in the near future.
