319 research outputs found
Split-SUSY versus SUSY GUTS
The gauge coupling unification is one of main motivations in the split-SUSY
scenario, and the existence of the grand unified theories (GUTs) is assumed. We
examine how to realize split-SUSY mass spectrum in the context of GUTs and find
that the construction of split-SUSY GUTs is by no means straightforward. With
R-symmetry breaking sources in the GUT sector,
GUT particles play a role of the messengers in the gauge mediation scenario
and their contributions to gaugino masses can be sizable. We find the upper
bound on soft scalar masses of
O(10^{10}) GeV from consistency for constructing the split-SUSY GUT. Also, we
discuss the attempt to construct R-symmetric GUT models.Comment: 13 page
Structure of split supersymmetry and simple models
We derive in detail a condition on the Higgs mass parameters that is
necessary for the recently proposed ``split supersymmetry''
(split SUSY) scenario to provide a realistic magnitude of . The
nature of this condition can be understood by showing how the Higgs sector of
the minimal supersymmetric Standard Model reduces to that of the Standard Model
in the heavy limit of the soft supersymmetry breaking
Higgs mass parameters. Based on this condition, we present some simple
supersymmetry breaking models that each provides a realistic split-SUSY mass
spectrum, in accordance with the scale of the gravitino mass () in
relation to those of the soft scalar mass () and the gaugino mass
() employed in each, namely , and , respectively, with the
relation of the split-SUSY mass spectrum.Comment: 11 page
Multiple-point principle with a scalar singlet extension of the Standard Model
We suggest a scalar singlet extension of the standard model, in which the
multiple-point principle (MPP) condition of a vanishing Higgs potential at the
Planck scale is realized. Although there have been lots of attempts to realize
the MPP at the Planck scale, the realization with keeping naturalness is quite
difficult. Our model can easily achieve the MPP at the Planck scale without
large Higgs mass corrections. It is worth noting that the electroweak symmetry
can be radiatively broken in our model. In the naturalness point of view, the
singlet scalar mass should be of or less. We also
consider right-handed neutrino extension of the model for neutrino mass
generation. The model does not affect the MPP scenario, and might keep the
naturalness with the new particle mass scale beyond TeV, thanks to accidental
cancellation of Higgs mass corrections.Comment: 17 pages, 6 figures, version accepted for publication in PTE
Bosonic seesaw mechanism in a classically conformal extension of the Standard Model
We suggest the so-called bosonic seesaw mechanism in the context of a
classically conformal extension of the Standard Model with two
Higgs doublet fields. The symmetry is radiatively broken via the
Coleman-Weinberg mechanism, which also generates the mass terms for the two
Higgs doublets through quartic Higgs couplings. Their masses are all positive
but, nevertheless, the electroweak symmetry breaking is realized by the bosonic
seesaw mechanism. Analyzing the renormalization group evolutions for all model
couplings, we find that a large hierarchy among the quartic Higgs couplings,
which is crucial for the bosonic seesaw mechanism to work, is dramatically
reduced toward high energies. Therefore, the bosonic seesaw is naturally
realized with only a mild hierarchy, if some fundamental theory, which provides
the origin of the classically conformal invariance, completes our model at some
high energy, for example, the Planck scale. We identify the regions of model
parameters which satisfy the perturbativity of the running couplings and the
electroweak vacuum stability as well as the naturalness of the electroweak
scale.Comment: 5 pages, 2 figures, published version in PL
Universally Leptophilic Dark Matter From Non-Abelian Discrete Symmetry
The positron anomaly recently reported by the cosmic-ray measurements can be
explained by the decaying dark matter scenario, where it decays mainly into
leptons with the lifetime of O(10^26) second. When the dark matter is a
fermionic particle, the lifetime of this order is known to be obtained by a
dimension 6 operator suppressed by the unification scale 10^16 GeV, while such
decay operators do not necessarily involve only leptons. In addition, the
scenario would be spoiled if there exist lower-dimensional operators inducing
the dark matter decay. We show in this letter that a single non-Abelian
discrete symmetry such as A_4 is possible to prohibit all such harmful
(non-leptonically coupled and lower-dimensional) operators. Moreover, the dark
matter decays into charged leptons in a flavor-blind fashion due to the
non-Abelian flavor symmetry, which results in perfect agreements not only with
the PAMELA data but also with the latest Fermi-LAT data reported very recently.
We also discuss some relevance between the discrete symmetry and neutrino
physics.Comment: 13 pages, 2 tables, 1 figur
Frequency analysis of electroencephalogram recorded from a bottlenose dolphin (Tursiops truncatus) with a novel method during transportation by truck
In order to obtain information regarding the correlation between an electroencephalogram (EEG) and the state of a dolphin, we developed a noninvasive recording method of EEG of a bottlenose dolphin (Tursiops truncatus) and an extraction method of true-EEG (EEG) from recorded-EEG (R-EEG) based on a human EEG recording method, and then carried out frequency analysis during transportation by truck. The frequency detected in the EEG of dolphin during apparent awakening was divided conveniently into three bands (5–15, 15–25, and 25–40 Hz) based on spectrum profiles. Analyses of the relationship between power ratio and movement of the dolphin revealed that the power ratio of dolphin in a situation when it was being quiet was evenly distributed among the three bands. These results suggested that the EEG of a dolphin could be detected accurately by this method, and that the frequency analysis of the detected EEG seemed to provide useful information for understanding the central nerve activity of these animals
Spatial control of the microtubule-associated protein complex Alp7-Alp14 (TACC-TOG) in fission yeast
学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 渡邊 嘉典, 東京大学教授 飯野 雄一, 東京大学教授 太田 邦史, 東京大学教授 塩見 美喜子, 東京大学准教授 大杉 美穂University of Tokyo(東京大学
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