6,403 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
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
Vacuum Stability, Perturbativity, EWPD and Higgs-to-diphoton rate in Type II Seesaw Models
We study constraints from perturbativity and vacuum stability as well as the
EWPD in the type II seesaw model. As a result, we can put stringent limits on
the Higgs triplet couplings depending on the cut-off scale. The EWPD tightly
constrain the Higgs triplet mass splitting to be smaller than 40 GeV. Analyzing
the Higgs-to-diphoton rate in the allowed parameter region, we show a possible
enhancement by up to 100 % and 50 % for the cut-off scale of 100 TeV and
GeV, respectively, if the doubly charged Higgs boson mass is as low
as 100 GeV.Comment: Figs modified, reference added, matches with published versio
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
Environmental factors differentially affect epistaxis among preschool and school-aged children
IntroductionEnvironmental factors are closely associated with pediatric epistaxis. Whether this association differs according to age has not been previously reported. Therefore, we tried to evaluate the differences in associations between environmental factors and epistaxis in children of different ages.MethodsA total of 20,234 patients with epistaxis who visited the hospital between January 1, 2002, and December 31, 2015, were enrolled in this study. The patients were divided into two groups according to their ages: preschool-aged (<6 years) and school-aged children (6–18 years). Daily, monthly, and yearly data on environmental factors were collected. We performed a stepwise logistic regression to identify the potential environmental risk factors for epistaxis in each age group.ResultsThe mean number of epistaxis cases per month in both groups was highest in September. The cases were lowest in February in preschool-aged children and in November in school-aged children. Temperature, humidity, maximum wind speed, and sunshine duration were associated with epistaxis in preschool-aged children. Average wind speed, particulate matter (>10 μm diameter), temperature, humidity, sunshine duration, and sulfur dioxide concentration were associated with epistaxis in school-aged children.ConclusionThis study indicates that the differences in environmental risk factors for epistaxis are associated with the patient’s age
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