4,813 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.
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
Analysis of Performance for NAND Flash Based SSDs via Using Host Semantic Information
The use of flash memory based storage devices is rapidly increasing, and user demands for high performance are also constantly increasing. The performance of the flash storage device is greatly influenced by cleaning operations of Flash Translation Layer (FTL). Various studies have been conducted to lower the cost of cleaning operations. However, there are limits to achieve sufficient performance improvement of flash storages without help of a host system, with only limited information in storage devices. Recently, SCSI, eMMC, and UFS standards provide an interface for sending semantic information from a host system to a storage device. In this paper, we analyze effects of semantic information on performance and lifetime of flash storage devices. We evaluate performance and lifetime improvement through SA-FTL (Semantic Aware Flash Translation Layer), which can take advantage of semantic information in storage devices. Experiments show that SA-FTL improves performance and lifetime of flash based storages by up to 30 and 35%, respectively, compared to a simple page-level FTL
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