Takeshi Araki

Publications (8)0 Total impact

• Source

  Available from: ArXiv

  Article: Signatures of Dark Matter in Inert Triplet Models

  Takeshi Araki, C. Q. Geng, Keiko I. Nagao
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  ABSTRACT: In this talk, we will review the signatures of dark matter in two inert triplet models. For the first model with the hypercharge Y=0, the dark matter mass around 5.5 TeV is favored by both the WMAP data and the direct detection. In contrast, for the second model of Y=2, it is excluded by the direct detection experiments although dark matter with its mass around 2.8 TeV is allowed by WMAP.
  08/2011;
• Source

  Available from: ArXiv

  Article: Dark Matter in Inert Triplet Models

  Takeshi Araki, C. Q. Geng, Keiko I. Nagao
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  ABSTRACT: We study the inert triplet models, in which the standard model (SM) is extended to have a new SU(2)L triplet scalar (Y=0 or 2) with an Z2 symmetry. We show that the neutral component of the triplet can be a good dark matter candidate. In particular, for the hypercharge Y=0 triplet model, the WMAP data favors the region where the dark matter mass is around 5.5 TeV, which is also consistent with the direct detection experiments. In contrast, for the Y=2 model, although dark matter with its mass around 2.8 TeV is allowed by WMAP, it is excluded by the direct detection experiments because the spin-independent cross section is enhanced by the Z mediated tree-level scattering process.
  02/2011;
• Source

  Available from: ArXiv

  Article: mu-tau symmetry in Zee-Babu model

  Takeshi Araki, C. Q. Geng
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  ABSTRACT: We study the Zee-Babu two-loop neutrino mass generation model and look for a possible flavor symmetry behind the tri-bimaximal neutrino mixing. We find that there probably exists the mu-tau symmetry in the case of the normal neutrino mass hierarchy, whereas there may not be in the inverted hierarchy case. We also propose a specific model based on a Froggatt-Nielsen-like $Z_5$ symmetry to naturally accomplish the mu-tau symmetry on the neutrino mass matrix for the normal hierarchy case. Comment: 12 pages, 1 figure; final version
  06/2010;
• Source

  Available from: ArXiv

  Article: Leptogenesis with Friedberg-Lee Symmetry

  Takeshi Araki, C. Q. Geng
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  ABSTRACT: We consider the $\mu-\tau$ symmetric Friedberg-Lee (FL) symmetry for the neutrino sector and show that a specific FL translation leads to the tribimaximal mixing pattern of the Maki-Nakagawa-Sakata (MNS) matrix. We also apply the symmetry to the type-I seesaw framework and address the baryon asymmetry of the universe through the leptogenesis mechanism. We try to establish a relation between the net baryon asymmetry and CP phases included in the MNS matrix. Comment: Talk given at International Workshop on Dark Matter, Dark Energy and Matter-Antimatter Asymmetry, Hsinchu, Taiwan, 20-21 Nov. 2009, to be published in Modern Physics Letters A, reference added
  04/2010;
• Source

  Available from: ArXiv

  Article: Leptogenesis in a model with Friedberg-Lee symmetry

  Takeshi Araki, C. Q. Geng
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  ABSTRACT: We study the matter-antimatter asymmetry through the leptogenesis mechanism in a specific model with the Friedberg-Lee (FL) symmetry.We relate the leptogenesis with the CP violating Dirac and Majorana phases in the Maki-Nakagawa-Sakata leptonic mixing matrix and illustrate the net baryon asymmetry of the universe in terms of these phases. Comment: 14 pages, 8 figures. v2: typos corrected, minor changes, accepted version in PLB
  06/2009;
• Source

  Available from: ArXiv

  Article: Constraints on the Timeon Model

  Takeshi Araki, C. Q. Geng
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  ABSTRACT: The timeon model recently proposed by Friedberg and Lee has a potential problem of flavor changing neutral currents (FCNCs) if the mass of the timeon is small. In order to avoid, we introduce a small dimensionless parameter to suppress FCNCs. Even in this case, we find that the timeon mass must be larger than 151 GeV to satisfy all the constraints from processes involving FCNCs in the quark sectors. We also extend the timeon model to the lepton sector and examine the leptonic processes. Comment: 10 pages, 1 figure, published version in PRD
  01/2009;
• Source

  Available from: ArXiv

  Article: Tri-Bimaximal Mixing from Twisted Friedberg-Lee Symmetry

  Takeshi Araki, Ryo Takahashi
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  ABSTRACT: We investigate the Friedberg-Lee (FL) symmetry and its promotion to include the $\mu - \tau$ symmetry, and call that the twisted FL symmetry.Based on the twisted FL symmetry, two possible schemes are presented toward the realistic neutrino mass spectrum and the tri-bimaximal mixing.In the first scheme, we suggest the semi-uniform translation of the FL symmetry.The second one is based on the $S_3$ permutation family symmetry.The breaking terms, which are twisted FL symmetric, are introduced.Some viable models in each scheme are also presented. Comment: 14 pages, no figure. v2: 16 pages, modified some sentences, appendix added, references added. v3: 14 pages, composition simplified, accepted version in EPJC
  11/2008;
• Article: Leptogenesis in a model with Friedberg–Lee symmetry

  Takeshi Araki, C.Q. Geng
  [show abstract] [hide abstract]
  ABSTRACT: We study the matter–antimatter asymmetry through the leptogenesis mechanism in a specific model with the Friedberg–Lee (FL) symmetry. We relate the leptogenesis with the CP violating Dirac and Majorana phases in the Maki–Nakagawa–Sakata leptonic mixing matrix and illustrate the net baryon asymmetry of the universe in terms of these phases.
  Physics Letters B.