Probing Models of Dirac Neutrino Masses via the Flavor Structure of the Mass Matrix

We classify models of the Dirac neutrino mass by concentrating on flavor structures of the mass matrix. The advantage of our classification is that we do not need to specify detail of models except for Yukawa interactions because flavor structures can be given only by products of Yukawa matrices. All possible Yukawa interactions between leptons (including the right-handed neutrino) are taken into account by introducing appropriate scalar fields. We also take into account the case with Yukawa interactions of leptons with the dark matter candidate. Then, we see that flavor structures can be classified into seven groups. The result is useful for the efficient test of models of the neutrino mass. One of seven groups can be tested by measuring the absolute neutrino mass. Other two can be tested by probing the violation of the lepton universality in $\ell \to \ell^\prime \nu \overline{\nu}$. In order to test the other four groups, we can rely on searches for new scalar particles at collider experiments.Comment: 21 pages, 20 eps files, published in PL

New model for radiatively generated Dirac neutrino masses and lepton flavor violating decays of the Higgs boson

We propose a new mechanism to explain neutrino masses with lepton number conservation, in which the Dirac neutrino masses are generated at the two-loop level involving a dark matter candidate. In this model, branching ratios of lepton flavor violating decays of the Higgs boson can be much larger than those of lepton flavor violating decays of charged leptons. If lepton flavor violating decays of the Higgs boson are observed at future collider experiments without detecting lepton flavor violating decays of charged leptons, most of the models previously proposed for tiny neutrino masses are excluded while our model can still survive. We show that the model can be viable under constraints from current data for neutrino experiments, searches for lepton flavor violating decays of charged leptons and dark matter experiments.Comment: 26 pages, 9 eps file

Writhes and 2k2k-moves for virtual knots

A $2k$-move is a local deformation adding or removing $2k$ half-twists. We show that if two virtual knots are related by a finite sequence of $2k$-moves, then their $n$-writhes are congruent modulo $k$ for any nonzero integer $n$, and their odd writhes are congruent modulo $2k$. Moreover, we give a necessary and sufficient condition for two virtual knots to have the same congruence class of odd writhes modulo $2k$.Comment: 10 pages, 14 figure

Pride and Status: Unpacking Two Divergent Pathways to Cooperation

Cooperation is essential for addressing social dilemma problems, especially in modern society with rapidly growing human populations and changing ecology. The scientific community and policymakers have recognized the potential of emotions to facilitate effective communication of sustainability and large-scale cooperation. However, research has not yet explored which emotions are specifically linked to promoting cultures of cooperation and sustainability. This dissertation focuses on pride and its proposed dual nature in influencing prosocial motivations through status hierarchy. According to a prominent theory, pride consists of authentic pride and hubristic pride, both of which are tied to different types of status attainment, prestige and dominance. The main behavioral experiment in this study involved creating a status hierarchy and using the Ultimatum Game (UG) to test novel hypotheses. It was found that participants were more willing to offer a fair split of money to opponents who displayed a prestigious expression after outperforming them in three cognitive tasks. However, when participants played against a superior opponent who displayed dominance after outperforming them, they were no more likely to offer money compared to a neutral condition without any status differentiation. The results have important implications for the current literature on the relationship between pride and status and its role in promoting cooperation. Additionally, this research has practical applications, but there are several limitations that should be acknowledged. Future directions for further research challenging the two-facet theory of pride/status are discussed. Overall, this dissertation contributes to the understanding of the complex role of pride in cooperation and sheds light on the dynamics of human social interactions and status hierarchies