2,516 research outputs found
Forbidden Channels and SIMP Dark Matter
In this review, we focus on dark matter production from thermal freeze-out
with forbidden channels and SIMP processes. We show that forbidden channels can
be dominant to produce dark matter depending on the dark photon and / or dark
Higgs mass compared to SIMP.Comment: 5 pages, Prepared for the proceedings of the 13th International
Conference on Gravitation, 3-7 July 201
On thermal production of self-interacting dark matter
We consider thermal production mechanisms of self-interacting dark matter in
models with gauged symmetry. A complex scalar dark matter is stabilized
by the , that is the remnant of a local dark . Light dark matter
with large self-interaction can be produced from thermal freeze-out in the
presence of SM-annihilation, SIMP and/or forbidden channels. We show that dark
photon and/or dark Higgs should be relatively light for unitarity and then
assist the thermal freeze-out. We identify the constraints on the parameter
space of dark matter self-interaction and mass in cases that one or some of the
channels are important in determining the relic density.Comment: 26 pages, 11 figures, Version to appear in Journal of High Energy
Physic
Biolocomotion Detection in Videos
Animals locomote for various reasons: to search for food, to find suitable habitat, to pursue prey, to escape from predators, or to seek a mate. The grand scale of biodiversity contributes to the great locomotory design and mode diversity. In this dissertation, the locomotion of general biological species is referred to as biolocomotion. The goal of this dissertation is to develop a computational approach to detect biolocomotion in any unprocessed video.
The ways biological entities locomote through an environment are extremely diverse. Various creatures make use of legs, wings, fins, and other means to move through the world. Significantly, the motion exhibited by the body parts to navigate through an environment can be modelled by a combination of an overall positional advance with an overlaid asymmetric oscillatory pattern, a distinctive signature that tends to be absent in non-biological objects in locomotion. In this dissertation, this key trait of positional advance with asymmetric oscillation along with differences in an object's common motion (extrinsic motion) and localized motion of its parts (intrinsic motion) is exploited to detect biolocomotion. In particular, a computational algorithm is developed to measure the presence of these traits in tracked objects to determine if they correspond to a biological entity in locomotion. An alternative algorithm, based on generic handcrafted features combined with learning is assembled out of components from allied areas of investigation, also is presented as a basis of comparison to the main proposed algorithm.
A novel biolocomotion dataset encompassing a wide range of moving biological and non-biological objects in natural settings is provided. Additionally, biolocomotion annotations to an extant camouflage animals dataset also is provided. Quantitative results indicate that the proposed algorithm considerably outperforms the alternative approach, supporting the hypothesis that biolocomotion can be detected reliably based on its distinct signature of positional advance with asymmetric oscillation and extrinsic/intrinsic motion dissimilarity
Unitary inflaton as decaying dark matter
We consider the inflation model of a singlet scalar field (sigma field) with
both quadratic and linear non-minimal couplings where unitarity is ensured up
to the Planck scale. We assume that a symmetry for the sigma field is
respected by the scalar potential in Jordan frame but it is broken explicitly
by the linear non-minimal coupling due to quantum gravity. We discuss the
impacts of the linear non-minimal coupling on various dynamics from inflation
to low energy, such as a sizable tensor-to-scalar ratio, a novel reheating
process with quartic potential dominance, and suppressed physical parameters in
the low energy, etc. In particular, the linear non-minimal coupling leads to
the linear couplings of the sigma field to the Standard Model through the trace
of the energy-momentum tensor in Einstein frame. Thus, regarding the sigma
field as a decaying dark matter, we consider the non-thermal production
mechanisms for dark matter from the decays of Higgs and inflaton condensate and
show the parameter space that is compatible with the correct relic density and
cosmological constraints.Comment: 36 pages, 7 figures, v2: minor corrections made and references added,
v3: discussion on preheating added, accepted for Journal of High Energy
Physics, v4: Lyman-alpha bound included and inflationary predictions refined
for perturbative reheatin
A minimal flavored for -meson anomalies
We consider an anomaly-free model with favorable couplings to heavy
flavors in the Standard Model(SM), as motivated by -meson anomalies at LHCb.
Taking the charge to be , we can
explain the -meson anomalies without invoking extra charged fermions or
flavor violation beyond the SM. We show that there is a viable parameter space
with a small that is compatible with other meson decays, tau lepton and
neutrino experiments as well as the LHC dimuon searches. We briefly discuss the
prospects of discovering the gauge boson at the LHC in the proposed model.Comment: 20 pages, 4 figures, v2: references and discussion on electroweak
precision test added, v3: Version to appear in Physical Review
The influences of restricted compensatory movement on activation pattern of gluteal muscles during unilateral weight-bearing exercise
We investigated changes in lateral pelvic tilt and activity of the gluteal muscles during one-leg standing with and without pressure biofeedback. Seventeen participants performed one-leg standing tests with pressure biofeedback (the threshold was set to the minimum change in pressure) and without biofeedback (standard one-leg standing). The lateral pelvic tilt was significantly lower in one-leg standing with pressure biofeedback than in standard one-leg standing (p < .05). In addition, gluteus medius and gluteus maximus activity was significantly greater during one-leg standing with pressure biofeedback than during standard one-leg standing (p < .05). Based on our results, restriction of compensatory movement can be used to increase activity of gluteal muscles when performing unilateral weight-bearing exercise such as one-leg standing.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2018R1C1B5085529)
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