Considering the experimental constraints on the free parameters of the 331 model with a leptonic sector consistent of five triplets, we investigate the lepton flavor violation(LFV) tau decays τ→μM with M = P and V,...Considering the experimental constraints on the free parameters of the 331 model with a leptonic sector consistent of five triplets, we investigate the lepton flavor violation(LFV) tau decays τ→μM with M = P and V,where P and V denote a pseudoscalar meson(π, η or η′) and a vector meson(ρ0, ω or φ), respectively. We find that the contributions of the 331 model to the LFV decays τ→μM mainly come from the new neutral gauge boson Z′. The 331 model considered in this paper can not make the values of the branching ratio Br(τ→μM) approach the corresponding experimental upper limits.展开更多
The one-loop contributions to the chromomagnetic dipole momentˆμt(q2)and electric dipole momentˆd t(q2)of the top quark are calculated within the reduced 331 model(RM331)for non-zero q2.It is argued that the results ...The one-loop contributions to the chromomagnetic dipole momentˆμt(q2)and electric dipole momentˆd t(q2)of the top quark are calculated within the reduced 331 model(RM331)for non-zero q2.It is argued that the results are gauge independent and thus represent valid observable quantities.In the RM331,ˆμt(q2)receives new contributions from two heavy gauge bosons,namely Z′and V±,and one neutral scalar boson h2,along with a new contribution from the standard model's Higgs boson via flavor changing neutral currents.The latter,which is also mediated by the Z′gauge boson and the scalar boson h2,can provide a non-vanishingˆd t(q2)if there is a CP-violating phase.The analytical results are presented in terms of both Feynman parameter integrals and Passarino-Veltman scalar functions,which are useful to cross-check the numerical results.Bothˆμt(q2)andˆd t(q2)are numerically evaluated for parameter values still allowed by the constraints from experimental data.It is found that the new one-loop contributions of the RM331 to the real(imaginary)part ofˆμt(q2)are of the order of 10−5(10−6),which means at least three orders of magnitude smaller than the standard model prediction but larger than the predictions of other models of new physics.In the RM331,the dominant contribution arises from the V±gauge boson for‖q‖in the 30-1000 GeV interval and a mass mV of the order of a few hundreds of GeV.As forˆd t(q2),it receives its largest contribution from h2 exchange and can reach values of the order of 10−19,i.e.,smaller than the contributions predicted by other standard model extensions.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.11275088the Natural Science Foundation of the Liaoning Scientific Committee under Grant No.201102114Foundation of Liaoning Educational Committee under Grant No.LT2011015
文摘Considering the experimental constraints on the free parameters of the 331 model with a leptonic sector consistent of five triplets, we investigate the lepton flavor violation(LFV) tau decays τ→μM with M = P and V,where P and V denote a pseudoscalar meson(π, η or η′) and a vector meson(ρ0, ω or φ), respectively. We find that the contributions of the 331 model to the LFV decays τ→μM mainly come from the new neutral gauge boson Z′. The 331 model considered in this paper can not make the values of the branching ratio Br(τ→μM) approach the corresponding experimental upper limits.
文摘The one-loop contributions to the chromomagnetic dipole momentˆμt(q2)and electric dipole momentˆd t(q2)of the top quark are calculated within the reduced 331 model(RM331)for non-zero q2.It is argued that the results are gauge independent and thus represent valid observable quantities.In the RM331,ˆμt(q2)receives new contributions from two heavy gauge bosons,namely Z′and V±,and one neutral scalar boson h2,along with a new contribution from the standard model's Higgs boson via flavor changing neutral currents.The latter,which is also mediated by the Z′gauge boson and the scalar boson h2,can provide a non-vanishingˆd t(q2)if there is a CP-violating phase.The analytical results are presented in terms of both Feynman parameter integrals and Passarino-Veltman scalar functions,which are useful to cross-check the numerical results.Bothˆμt(q2)andˆd t(q2)are numerically evaluated for parameter values still allowed by the constraints from experimental data.It is found that the new one-loop contributions of the RM331 to the real(imaginary)part ofˆμt(q2)are of the order of 10−5(10−6),which means at least three orders of magnitude smaller than the standard model prediction but larger than the predictions of other models of new physics.In the RM331,the dominant contribution arises from the V±gauge boson for‖q‖in the 30-1000 GeV interval and a mass mV of the order of a few hundreds of GeV.As forˆd t(q2),it receives its largest contribution from h2 exchange and can reach values of the order of 10−19,i.e.,smaller than the contributions predicted by other standard model extensions.
