In a novel parametrization of neutrino mixing and in the approximation of τ-lepton dominance, we show that the one-loop renormalization-group equations （RGEs） of Dirac neutrinos are different from those of Majorana...In a novel parametrization of neutrino mixing and in the approximation of τ-lepton dominance, we show that the one-loop renormalization-group equations （RGEs） of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tan β, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.展开更多
The Dirac neutrino masses could be simply generated by a neutrinophilic scalar doublet with a vacuum being dramatically different from the electroweak one.While the case with an eV-scale vacuum has been widely explore...The Dirac neutrino masses could be simply generated by a neutrinophilic scalar doublet with a vacuum being dramatically different from the electroweak one.While the case with an eV-scale vacuum has been widely explored previously,we exploit in this work the desert where the scalar vacuum is of O(keV)scale.In this regime,there would be rare hope to probe the keV-vacuum neutrinophilic scalar model via the lepton-flavor-violating processes,which makes it distinguishable from the widely considered eV-scale vacuum.Although such a keV-vacuum scenario is inert in the low-energy flavor physics,we show that the baryogenesis realized via the lightest Dirac neutrino can be a natural candidate in explaining the baryon asymmetry of the Universe.Furthermore,the Dirac neutrinos with a keV-vacuum scalar can generate a shift of the effective neutrino number within the range 0.097≤ΔN_(eff)≤0.112,which can be probed by the future Simons Observatory experiments.In particular,the model with a minimal valueΔN_(eff)=0.097 can already be falsified by the future CMB Stage-Ⅳand Large Scale Structure surveys,providing consequently striking exploratory avenues in the cosmological regime for such a keV-vacuum scenario.展开更多
Generation of neutrino mass in SO（4） model is proposed here. The algebraic structure of SO （4） is same as to that ofSU（2）L x SU（2）R. It is shown that the spontaneous symmetry breaking results three massive as ...Generation of neutrino mass in SO（4） model is proposed here. The algebraic structure of SO （4） is same as to that ofSU（2）L x SU（2）R. It is shown that the spontaneous symmetry breaking results three massive as well as three massless gauge bosons. The standard model theory according to which there exist three massive gauge bosons and a massless one is emerged from this model. In the framework ofSU（2）L x SU（2）R a small Dirac neutrino mass is derived. It is also shown that such mass term may vanish with a special choice. The Majorana mass term is not considered here and thus in this model the neutrino mass does not follow seesaw structure.展开更多
基金The project supported in part by National Natural Science Foundation of China
文摘In a novel parametrization of neutrino mixing and in the approximation of τ-lepton dominance, we show that the one-loop renormalization-group equations （RGEs） of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tan β, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.
基金Supported by the National Natural Science Foundation of China(12135006,12075097,12047527,11775092)by the Fundamental Research Funds for the Central Universities(CCNU20TS007,CCNU19TD012,CCNU22LJ004)。
文摘The Dirac neutrino masses could be simply generated by a neutrinophilic scalar doublet with a vacuum being dramatically different from the electroweak one.While the case with an eV-scale vacuum has been widely explored previously,we exploit in this work the desert where the scalar vacuum is of O(keV)scale.In this regime,there would be rare hope to probe the keV-vacuum neutrinophilic scalar model via the lepton-flavor-violating processes,which makes it distinguishable from the widely considered eV-scale vacuum.Although such a keV-vacuum scenario is inert in the low-energy flavor physics,we show that the baryogenesis realized via the lightest Dirac neutrino can be a natural candidate in explaining the baryon asymmetry of the Universe.Furthermore,the Dirac neutrinos with a keV-vacuum scalar can generate a shift of the effective neutrino number within the range 0.097≤ΔN_(eff)≤0.112,which can be probed by the future Simons Observatory experiments.In particular,the model with a minimal valueΔN_(eff)=0.097 can already be falsified by the future CMB Stage-Ⅳand Large Scale Structure surveys,providing consequently striking exploratory avenues in the cosmological regime for such a keV-vacuum scenario.
文摘Generation of neutrino mass in SO（4） model is proposed here. The algebraic structure of SO （4） is same as to that ofSU（2）L x SU（2）R. It is shown that the spontaneous symmetry breaking results three massive as well as three massless gauge bosons. The standard model theory according to which there exist three massive gauge bosons and a massless one is emerged from this model. In the framework ofSU（2）L x SU（2）R a small Dirac neutrino mass is derived. It is also shown that such mass term may vanish with a special choice. The Majorana mass term is not considered here and thus in this model the neutrino mass does not follow seesaw structure.
