276 research outputs found
Tauonic B decays in the Minimal Supersymmetric Standard Model
We study new physics effects on B decay processes including a final
particle, namely and . An important feature
of these processes is that a charged Higgs boson can contribute to the decay
amplitude at the tree level in models such as Two Higgs Doublet Model and the
Minimal Supersymmetric Standard Model (MSSM). We derive a resummed effective
Lagrangian for charged-Higgs mediated interactions in the MSSM with the Minimal
Flavor Violation. Including supersymmetric (SUSY) loop corrections for
down-type-quark and charged-lepton Yukawa couplings, we calculate the branching
ratios of the and processes. We find that
SUSY correction due to gluino-sbottom diagrams can change the Higgs exchange
contribution by %, whereas stau-neutralino diagrams can make corrections
up to 20%. We also discuss relationship between SUSY corrections in the tauonic
decays and flavor changing neutral current processes such as and .Comment: 29 pages, 22 figure
Low scale gravity mediation with warped extra dimension and collider phenomenology on the hidden sector
We propose a scenario of gravity mediated supersymmetry breaking (gravity
mediation) in a supersymmetric Randall-Sundrum model. In our setup, both of the
visible sector and the hidden sector co-exist on the infrared (IR) brane. We
introduce the Polonyi model as a simple hidden sector. Due to the warped
metric, the effective cutoff scale on the IR brane is ``warped down'', so that
the gravity mediation occurs at a low scale. As a result, the gravitino is
naturally the lightest superpartner (LSP) and contact interactions between the
hidden and the visible sector fields become stronger. We address
phenomenologies for various IR cutoff scales. In particular, we investigate
collider phenomenology involving a scalar field (Polonyi field) in the hidden
sector for the case with the IR cutoff around 10 TeV. We find a possibility
that the hidden sector scalar can be produced at the LHC and the International
Linear Collider (ILC). Interestingly, the scalar behaves like the Higgs boson
of the standard model in the production process, while its decay process is
quite different and, once produced, it will provide us with a very clean
signature. The hidden sector may be no longer hidden.Comment: 18 pages, 4 figures. typographical errors have been corrected and a
few new comments have been adde
Hidden particle production at the ILC
In a class of new physics models, new physics sector is completely or partly
hidden, namely, singlet under the Standard Model (SM) gauge group. Hidden
fields included in such new physics models communicate with the Standard Model
sector through higher dimensional operators. If a cutoff lies in the TeV range,
such hidden fields can be produced at future colliders. We consider a scalar
filed as an example of the hidden fields. Collider phenomenology on this hidden
scalar is similar to that of the SM Higgs boson, but there are several features
quite different from those of the Higgs boson. We investigate productions of
the hidden scalar at the International Linear Collider (ILC) and study the
feasibility of its measurements, in particular, how well the ILC distinguishes
the scalar from the Higgs boson, through realistic Monte Carlo simulations.Comment: the version to be published in PR
Cholecystokinin receptor antagonist, loxiglumide, inhibits invasiveness of human pancreatic cancer cell lines
AbstractRecently, cholecystokinin has been reported to be important in regulating the growth of pancreatic cancer. We investigated the effect of loxiglumide (LXG), a cholecytskinin receptor antagonist, on the invasiveness of two human pancreatic cancer cell lines. Cells were treated with LXG for 24 h, and examined in the invasion assay. The expression and activity of MMP-9 in supernatants from cancer cells were analyzed by Western blotting and zymogram. Interestingly, the invasiveness of cancer cells and expression of MMP-9 were decreased by LXG in a dose-dependent manner. LXG may be a useful therapeutic agent against pancreatic cancer
Theory on the Temperature Dependence of Giant Magnetoresistance
The temperature dependence of the giant magnetoresistance (GMR) for currents
parallel and perpendicular to the multilayer plane, is discussed by taking
account of the random exchange potentials, phonon scatterings and spin
fluctuations. The effect of spin fluctuations, which plays an important role at
finite temperatures, is included by means of the static functional-integral
method developed previously by the present author. Our model calculations well
explain the observed features of the parallel and perpendicular GMR of Fe/Cr
and Co/Cu multilayers recently reported by Gijs {\it et al}.Comment: 20 pages (LATEX), 5 figures available on request to
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Microstructure, Mechanical Properties and Fracture Behavior of α Particle Irradiated Type 316 Stainless Steel
The present work is a research of the effect of helium on the microstructure, mechanical properties and fracture behaviors of a type 316 austenitic steel. Helium implantation was performed by 30-MeV α-particle injection on very small size specimens, using a cyclotron. Average helium content in a He-deposited region was up to 2000 appm He. In the case of 2000appm He implantation, intergranular fracture was sometimes observed on the helium deposited region after tensile test at room temperature. At elevated temperature test, however, this material showed the transition of fracture mode from transgranular-ductile fracture at 773K to intergranular fracture at 873. In the case of 500 appm He implantation, the transition of fracture mode was recognized at a temperature range of 873K to 973K
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