588 research outputs found
-term as the origin of baryon and lepton number asymmetry
We study a possibility of combining an origin of the -term and the
baryon and lepton number asymmetry. If we assume that the -term is
generated through a flat direction of a singlet scalar field, the coherent
oscillation of this condensate around its potential minimum can store the
global U(1) charge asymmetry. The decay of this condensate can distribute this
asymmetry into the lepton and baryon number asymmetry as far as its decay
occurs at an appropriate temperature. We examine the compatibility between this
scenario and the small neutrino mass generation based on both the ordinary
seesaw mechanism and the bilinear R-parity violating terms.Comment: 22 pages, published versio
Attempt of numerical design recognition of space structure to use possession energy theory of space frame - shell and spatial structures -
p. 742-753In this 21st century, we are faced with the issue how we use materials of the earth
ecologically. We, researchers, designers and engineers in architectural circles, always run after the possibilities of architectures that composed of limited materials of the earth.
However, some architects are often put an emphasis on their artistic designs. That causes un-ecological structures.
In this report, I try to judge an artistic realization numerically by the method of potential
structural energy which uses a function and a diagram.
This method can lead you to realize that structure is easy on the environment showed on a diagram given by analysing and reviewing a proper performance of a structure numerically based on "potential structural energy".Imagawa, N.; Suematsu, S.; Inoda, D.; Yamamoto, N. (2009). Attempt of numerical design recognition of space structure to use possession energy theory of space frame - shell and spatial structures -. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/673
Mass bound of the lightest neutral Higgs scalar in the extra U(1) models
The upper mass bound of the lightest neutral Higgs scalar is studied in the
problem solvable extra U(1) models by using the analysis of the
renormalization group equations. In order to restrict the parameter space we
take account of a condition of the radiative symmetry breaking and some
phenomenological constraints. We compare the bound obtained based on this
restricted parameter space with the one of the next to the minimal
supersymmetric standard model (NMSSM). Features of the scalar potential and
renormalization group equations of the Yukawa couplings among Higgs chiral
supermultiplets are rather different between them. They can reflect in this
bound.Comment: 22 pages, latex, 11 eps-figure
The Higgs Sector in a Extension of the MSSM
We consider the Higgs sector in an extension of the MSSM with extra SM
singlets, involving an extra gauge symmetry, in which the
domain-wall problem is avoided and the effective parameter is decoupled
from the new gauge boson mass. The model involves a rich Higgs
structure very different from that of the MSSM. In particular, there are large
mixings between Higgs doublets and the SM singlets, significantly affecting the
Higgs spectrum, production cross sections, decay modes, existing exclusion
limits, and allowed parameter range. Scalars considerably lighter than the LEP2
bound (114 GeV) are allowed, and the range is both allowed
and theoretically favored. Phenomenologically, we concentrate our study on the
lighter (least model-dependent, yet characteristic) Higgs particles with
significant SU(2)-doublet components to their wave functions, for the case of
no explicit CP violation in the Higgs sector. We consider their spectra,
including the dominant radiative corrections to their masses from the top/stop
loop. We computed their production cross sections and reexamine the existing
exclusion limits at LEP2. We outline the searching strategy for some
representative scenarios at a future linear collider. We emphasize that
gaugino, Higgsino, and singlino decay modes are indicative of extended models
and have been given little attention. We present a comprehensive list of model
scenarios in the Appendices.Comment: 49 pages, 17 figure
Sol-gel synthesis of molecular sieving silica membranes
Polymeric silica sol was synthesized by the acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate. Calcined unsupported membranes made from this sol showed microporous nature. Supported membranes on alumina were prepared by dipping and calcining. Helium showed activated diffusion with an apparent activation energy of 17 kJ mol−1. H2 permeation was comparable to that of helium under identical conditions. N2, Ar, O2, C3H6, C3H8, n-C4H10 and i-C4H10 permeation values were extremely small and therefore difficult to fit appropriate diffusion models. At 303 K hydrocarbon permeation was about 2 times higher than that of N2, Ar or O2. permselectivity around 1000 and helium permeation in the order of 10−7–10−8 mol m−2 s−1 Pa−1 were measured in the temperature range of 303–460 K. Comparison of Eact, selectivity and He and N2 permeation of different samples evidenced the dependence of nitrogen flux on processing defects. Obviously permeation rate of nitrogen molecule was insignificant through majority pores of the membrane
Synthesis of gas and vapor molecular sieving silica membranes and analysis of pore size and connectivity
Pervaporation and gas permeation properties of microporous silica membranes made by a sol−gel method are discussed. Defect free molecular sieving membranes are prepared by a dip coating process. The molecular sieving performance was measured and controlled based on gas permeation behavior of the membranes. The apparent activation energy for helium permeation and He/N2 perm-selectivity values were used as the parameters for optimization of the membrane performance. The membranes with very high activation energy for He diffusion were used for pervaporation studies with a methanol/MTBE mixture at 323 K. Separation factor values as high as 260 were measured at a total liquid flux of 0.3 kg/m2 hr. Sorption studies performed on corresponding silica gels revealed a separation mechanism based on diffusion of vapor molecules. Permeation of the vapor molecules through the micropores followed an activated diffusion mechanism. The gas permeation data could provide an understanding of the pore size distribution of the membrane, and the vapor sorption and diffusion data on the size and connectivity of the membrane pores
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