RISS 학술연구정보서비스

검색
다국어 입력

http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.

변환된 중국어를 복사하여 사용하시면 됩니다.

예시)
  • 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
  • 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
닫기
    인기검색어 순위 펼치기

    RISS 인기검색어

      검색결과 좁혀 보기

      • 좁혀본 항목

      • 좁혀본 항목 보기순서

        • 원문유무
        • 음성지원유무
          • 원문제공처
          • 등재정보
          • 학술지명
          • 주제분류
          • 발행연도
          • 작성언어
          • 저자

        오늘 본 자료

        • 오늘 본 자료가 없습니다.
        더보기
        • 무료
        • 기관 내 무료
        • 유료
        • SCISCIESCOPUS

          Classically conformal radiative neutrino model with gauged B-L symmetry

          Okada, H.,Orikasa, Y. North-Holland Pub. Co 2016 Physics letters. Section B Vol.760 No.-

          We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B-L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B-L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ→eγ), the current bound on the Z<SUP>'</SUP> mass at the CERN Large Hadron Collider, and neutrino oscillations.

        • Nonthermal dark matter models and signals

          Okada, Hiroshi,Orikasa, Yuta,Toma, Takashi American Physical Society 2016 Physical Review D Vol.93 No.5

          <P>Many experiments exploring weakly interacting massive particles (WIMPs) such as direct, indirect and collider searches have been carried out until now. However, a clear signal of a WIMP has not been found yet and it makes us to suspect that WIMPs are questionable as a dark matter candidate. Taking into account this situation, we propose two models in which dark matter relic density is produced by decay of a metastable particle. In the first model, the metastable particle is a feebly interacting massive particle, which is the so-called FIMP, produced by freeze-in mechanism in the early universe. In the second model, the decaying particle is thermally produced the same as the usual WIMP. However decay of the particle into dark matter is led by a higher dimensional operator. As a phenomenologically interesting feature of nonthermal dark matter discussed in this paper, a strong sharp gamma-ray emission as an indirect detection signal occurs due to internal bremsstrahlung, although some parameter space has already been ruled out by this process. Moreover combining other experimental and theoretical constraints such as dark matter relic density, big bang nucleosynthesis, collider, gamma-rays and perturbativity of couplings, we discuss the two nonthermal DM models.</P>

        • Radiative seesaw model with degenerate Majorana dark matter

          Nomura, Takaaki,Okada, Hiroshi,Orikasa, Yuta American Physical Society 2016 Physical Review D Vol.93 No.11

          <P>We study a three-loop-induced neutrino mass model with exotic vectorlike isospin doublet leptons which contain a dark matter candidate. Then we explore lepton flavor violations and dark matter physics in a coannihilation system. In this paper, the nearly degenerate Majorana fermion dark matter can naturally be achieved at the two-loop level, while the mass splitting can be larger than O (200) keV which is required from the constraint of the direct detection search with spin-independent inelastic scattering through the Z-boson portal. As a result, a monochromatic photon excess, with threshold energy greater than O(200) keV, is predicted in our model and could be measured through indirect detection experiments such as INTEGRAL.</P>

        • SCISCIESCOPUS

          Discriminative phenomenological features of scale invariant models for electroweak symmetry breaking

          Hashino, K.,Kanemura, S.,Orikasa, Y. North-Holland Pub. Co 2016 Physics letters. Section B Vol.752 No.-

          <P>Classical scale invariance (CSI) may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically at the quantum level by the Coleman-Weinberg mechanism. We discuss discriminative features of these models. First, using the experimental value of the mass of the discovered Higgs boson h(125), we obtain an upper bound on the mass of the lightest additional scalar boson (similar or equal to 543 GeV), which does not depend on its isospin and hypercharge. Second, a discriminative prediction on the Higgs-photon-photon coupling is given as a function of the number of charged scalar bosons, by which we can narrow down possible models using current and future data for the di-photon decay of h(125). Finally, for the triple Higgs boson coupling a large deviation (similar to+70%) from the SM prediction is universally predicted, which is independent of masses, quantum numbers and even the number of additional scalars. These models based on CSI can be well tested at LHC Run II and at future lepton colliders. (C) 2015 The Authors. Published by Elsevier B.V.</P>

        • SU(2)Lseptet scalar linking to a radiative neutrino model

          Nomura, Takaaki,Okada, Hiroshi,Orikasa, Yuta American Physical Society 2016 Physical Review D Vol.94 No.5

          <P>We study a radiative neutrino model with a SU(2) septet scalar with hypercharge Y = 2 where active neutrino mass is induced at a one-loop level. Calculating a one-loop diagram, mass matrices for an active neutrino are derived. We also analyze lepton flavor violations, the anomalous magnetic moment of a muon, and the flavor-violating Higgs decay h -> mu tau. Then, sizable muon g - 2 and similar to 1% of BR(h -> mu tau) could be obtained in our setup. Furthermore, the collider signature of the septet is discussed, and we focus on the quadratically charged scalar at the LHC 14 TeV. We find that it could be discovered up to 1.5 TeV mass by searching multicharged lepton signal events.</P>

        • Radiative seesaw mechanism in a minimal 3-3-1 model

          Okada, Hiroshi,Okada, Nobuchika,Orikasa, Yuta American Physical Society 2016 Physical Review D Vol.93 No.7

          <P>We study the neutrino sector in a minimal SU(3)(L) x U(1)(X) model, in which its mass is generated at a one-loop level with the charged lepton mass, and hence, there exists a strong correlation between the charged-lepton mass and the neutrino mass. We identify the parameter region of this model to satisfy the current neutrino oscillation data as well as the constraints on lepton flavor violating processes. We also discuss a possibility to explain the muon anomalous magnetic moment.</P>

        • SCISCIESCOPUS

          Radiative neutrino mass in alternative left–right model

          Nomura, Takaaki,Okada, Hiroshi,Orikasa, Yuta Springer-Verlag 2017 European Physical Journal C Vol.77 No.2

          <P>We propose a radiative seesaw model in an alternative left-right model without any bidoublet scalar fields, in which all the fermion masses in the standard model are generated through a canonical seesaw mechanism at the tree level. On the other hand the observed neutrino masses are generated at two-loop level. In this paper we focus on the neutrino sector and show how to induce the active neutrino masses. Then we discuss the observed neutrino oscillation, constraints from lepton flavor violations, new sources of the muon anomalous magnetic moment, a long-lived dark matter candidate with keV scale mass, and collider physics.</P>

        • Higgs phenomenology in the minimalSU(3)L×U(1)Xmodel

          Okada, Hiroshi,Okada, Nobuchika,Orikasa, Yuta,Yagyu, Kei American Physical Society 2016 Physical Review D Vol.94 No.1

          <P>We investigate the phenomenology of a model based on the SU(3)(c) x SU(3)(L) x U(1)(X) gauge theory, the so-called 331 model. In particular, we focus on the Higgs sector of the model which is composed of three SU(3)L triplet Higgs fields and is the minimal form for realizing a phenomenologically acceptable scenario. After the spontaneous symmetry breaking SU(3)(L) x U(1)(X) -> SU(2)(L) x U(1)(Y), our Higgs sector effectively becomes that with two SU(2)(L) doublet scalar fields, in which the first-and the second-generation quarks couple to a different Higgs doublet from that which couples to the third-generation quarks. This structure causes the flavor-changing neutral current mediated by Higgs bosons at the tree level. By taking an alignment limit of the mass matrix for the CP-even Higgs bosons, which is naturally realized in the case with the breaking scale of SU(3)(L) x U(1)(X) much larger than that of SU(2)(L) x U(1)(Y), we can avoid current constraints from flavor experiments such as the B-0-(B) over bar (0) mixing even for the Higgs bosons masses that are O(100) GeV. In this allowed parameter space, we clarify that a characteristic deviation in quark Yukawa couplings of the Standard Model-like Higgs boson is predicted, which has a different pattern from that seen in two Higgs doublet models with a softly broken Z(2) symmetry. We also find that the flavor-violating decay modes of the extra Higgs boson, e.g., H/A -> tc and H-+/- -> ts, can be dominant, and they yield the important signature to distinguish our model from the two Higgs doublet models.</P>

        맨 위로 스크롤 이동