Cold Dark Matters in U(1)' Models

We consider models with extra U(1)' gauge symmetry that is broken spontaneously. In the models, there are cold dark matter candidates which are charged under U(1)' symmetry. Depending on the charge assignment, we can evade the strong bound from the Drell-Yang process, and consider the scenario that the dark matters strongly interact with the fermions in the Standard Model through the extra gauge boson exchanging. As an illustrative example, we discuss a supersymmetric gauged U(1)_B \times U(1)_L model and see that not only correct relic density but also the DAMA/CoGeNT excess can be achieved by the dark matters.Comment: 5 pages, 2 figures. Talk given at the 7th international workshop on the dark side of the Universe (DSU2011), Sept.26-30, KITPC, Beijing. To appear in the proceeding

Study of dark matter physics in non-universal gaugino mass scenario

We study dark matter physics in the Minimal Supersymmetric Standard Model with non-universal gaugino masses at the unification scale. In this scenario, the specific ratio of wino and gluino masses realizes the electro-weak scale naturally and achieves 125 GeV Higgs boson mass. Then, relatively light higgsino is predicted and the lightest neutral particle, that is dominantly given by the neutral component of higgsino, is a good dark matter candidate. The direct detection of the dark matter is sensitive to not only a higgsino mass but also gaugino masses significantly. The upcoming XENON1T experiment excludes the parameter region where bino or gluino is lighter than about 2.5 TeV if the higgsino and the gaugino mass parameters have same signs. We see that the direct detection of dark matter gives stronger bound than the direct search at the LHC experiment when higgsino sizably contributes to the dark matter abundanceComment: 21 pages, 5 figures, 1 tabl

B -> D^(*) tau nu and B -> tau nu in chiral U(1)' models with flavored multi Higgs doublets

We discuss semileptonic and leptonic B decays, B to D^{(*)} tau nu and B to tau nu, in the chiral U(1)' models which were proposed by the present authors in the context of the top forward-backward asymmetry (A^t_FB) observed at the Tevatron. In these models, extra Higgs doublets with nonzero U(1)' charges are required in order to make the realistic mass matrix for up-type quarks. Then the extra (pseudo)scalars contribute to A^t_FB with large flavor-changing Yukawa couplings involving top quark. The contribution of the charged Higgs to A^t_FB is negligible, but it may significantly affect B decays: especially, B to D^(*) tau nu and B to tau nu. We investigate constraints on the B decays, based on the recent results in BaBar and Belle experiments, and discuss the possibility that the allowed parameter region in the B decays can achieve large A^t_ FB.Comment: 19 pages, 8 figures, version published in JHE

An exploratory study of the sexual health knowledge and attitudes of Asian male student sojourners in New Zealand

This study looked into the sexual and general health attitudes of Asian male student sojourners in New Zealand. The following issues on sexual and general health were probed: level of awareness, views and perceptions, levels of knowledge, main sources of information, and cultural factors in seeking health information. An Internet-mediated survey was employed to gather data on this sensitive topic. Sixty-six participants from Waikato, Massey, Canterbury, and Otago Universities answered the questionnaire. In addition, key-informant interviews with health providers were conducted to provide additional data. Data from the survey indicated a high level of health awareness concerning both general and sexual health maintenance, but there was cultural reluctance to discuss health issues, especially sexual health. General and sexual health matters were regarded as highly personal and sensitive, which they discussed with close associates. Findings from the study suggest the need for culturally appropriate approaches to improve Asian male students' access to health services

Top Forward-backward asymmetry at the Tevatron vs. Charge asymmetry at the LHC in chiral U(1)′U(1)' models with flavored Higgs fields

An extra $U(1)'$ model with $Z'$ coupled only to the right-handed (RH) up-type quarks has been one of the popular models for the Tevatron top forward-backward asymmetry (FBA), and has been excluded by the same-sign top-pair productions at the LHC. However, the original $Z'$ model is not physical, since the up-type quarks are massless including the top quark. This disaster can be evaded if the Higgs sector is extended by including new Higgs doublets with nonzero $U(1)'$ charges. We find that some parameter regions could achieve not only the top FBA at the Tevatron, but also the charge asymmetry at the LHC without exceeding the upper limit of the same-sign top-quark pair production at the LHC. The lesson is that it is mandatory to extend the Higgs sector whenever one considers chiral gauge symmetries beyond the SM gauge group. Otherwise some fermions remain massless, and thus it is meaningless to work on phenomenology without the extra Higgs doublets with new chiral gauge charges.Comment: Contribution to HCP2012 Proceedin