5,676 research outputs found
Decaying axinolike dark matter: Discriminative solution to small-scale issues
The latest Lyman- forest data severely constrain the conventional
warm dark matter solution to small-scale issues in the cold dark matter
paradigm. It has been also reported that unconstrained astrophysical processes
may address the issues. In response to this situation, we revisit the decaying
dark matter solution to the issues, discussing possible signatures to
discriminate decaying dark matter from astrophysical processes as a solution to
small-scale issues. We consider an axinolike particle (ALPino) decaying into an
axionlike particle (ALP) and gravitino with the lifetime around the age of the
Universe. The ALPino mass is sub-PeV and slightly ()
larger than the gravitino mass, and thus the dark matter abundance does not
alter virtually after the ALPino decays. On the other hand, the gravitino
produced from the ALPino decay obtains a kick velocity of , which is sufficiently larger than a circular velocity of dwarf galaxies to
impact their dark matter distributions. The Lyman- forest constraints
are relieved since only a small fraction (%) of dark matter experiences
the decay at that time. Decaying dark matter is thus promoted to a viable
solution to small-scale issues. The ALPino relic abundance is determined
predominantly by the decay of the lightest ordinary supersymmetric particle.
The monochromatic ALP emission from the ALPino decay is converted to photon under the Galactic magnetic field. The morphology of the
gamma-ray flux shows a distinctive feature of the model when compared to
decaying dark matter that directly decays into photons. Once detected, such
distinctive signals discriminate the decaying dark matter solution to
small-scale issues from unconstrained astrophysical processes.Comment: 6 pages, 3 figures; discussions improved, version accepted in PR
CP violating supersymmetric contributions to the electroweak parameter
Effects of CP violation on the supersymmetric electroweak correction to the
parameter are investigated. To avoid the EDM constraints, we require
that arg and the non-universal trilinear couplings
and also assume that gluinos are heavier than 400 GeV. The CP
phase arg() leads to large enhancement of the relative mass
splittings between and , which in turn
reduces the one-loop contribution of the stop and sbottom to . For
small , such a CP violating effect is prominent. We also study how
much the two-loop gluon and gluino contributions are affected by the CP phase.
Possible contributions to the parameter arising from the Higgs sector
with CP violation are discussed.Comment: 14 pages, Revtex, 4 eps figures, to appear in Phys. Rev. D (Rapid
Comm.
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Multicomponent seismic image matching and comparison - Fasken Ranch, Andrews County, Texas
textP-wave and S-wave multicomponent seismic data respond to lithology and fluid variations differently, providing interpreters with tools that supply additional information about subsurface geology. To interpret multicomponent data correctly, it is essential to identify and interpret corresponding seismic events in each seismic data set until they are correctly correlated and considered depth-registered. This study will focus on methods for analyzing P-P, SV-P, and P-SV seismic data integrated with well data to develop a better understanding of the subsurface geology within the study area. My work considers if and how multicomponent data can be matched with reflection patterns and when they cannot, how synthetic seismograms can be used to constrain depth-registration, and illustrates applications of 3C3D P-P, SV-P, P-SV seismic data located on the western shelf of the Midland Basin in Andrews County, Texas. An important point about this study is that it utilizes SV-P data generated by a vertical vibrator source and recorded with vertical geophones. This new concept allows shear wave information to be extracted from seismic surveys that have been recorded without the use of 3-component geophones or horizontal vibrators. Accordingly, this study will serve as one of the first case studies for determining the validity of these unique converted-mode seismic data.Geological Science
125 GeV Higgs as a pseudo-Goldstone boson in supersymmetry with vector-like matters
We propose a possibility of the 125 GeV Higgs being a pseudo-Goldstone boson
in supersymmetry with extra vector-like fermions. Higgs mass is obtained from
loops of top quark and vector-like fermions from the global symmetry breaking
scale f at around TeV. The mu, Bmu/mu \sim f are generated from the dynamics of
global symmetry breaking and the Higgs quartic coupling vanishes at f as tan
beta \simeq 1. The relation of msoft \sim with f \sim mu \sim m_soft
\sim TeV is obtained and large mu does not cause a fine tuning for the
electroweak symmetry breaking. The Higgs to di-photon rate can be enhanced from
the loop of uncolored vector-like matters. The stability problem of Higgs
potential with vector-like fermions can be nicely cured by the UV completion
with the Goldstone picture.Comment: 28 pages, 8 figure
A numerical study of scale effects on performance of a tractor type podded propeller
ABSTRACTIn this study, the scale effect on the performance of the podded propeller of tractor type is investigated. Turbulent flow computations are carried out for Reynolds numbers increasing progressively from model scale to full scale using the CFD analysis. The result of the flow calculation for model scale Reynolds numbers agrees well with that of the experiment of a large cavitation tunnel. The existing numerical analysis indicates that the performance of the podded propeller blades is mainly influenced by the advance coefficient and relatively little by the Reynolds number. However, the drag of pod housing with propeller in operation is different from that of pod housing without propeller due to the acceleration and swirl of propeller slipstream which is altered by propeller loading as well as the pressure recovery and friction according to Reynolds number, which suggests that the pod housing drag under the condition of propeller in operation is the key factor of the scale effect on the performance between model and full scale podded propellers. The so called ‘drag ratio’, which is the ratio of pod housing drag to total thrust of podded propeller, increases as the advance coefficient increases due to accelerated flow in the slipstream of the podded propeller. However, the increasing rate of the drag ratio reduces continuously as the Reynolds number increases from model to full scale progressively. The contribution of hydrodynamic forces, which acts on the parts composed of the pod housing with propeller operating in various loading conditions, to the thrust and the torque of the total propeller unit are presented for a range of Reynolds numbers from model to full scales
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