The mammalian retina is the most unique tissue among those that display robust circadian/diurnal oscillations. The retina is not only a light sensing tissue that relays light information to the ...brain, it has its own circadian “system” independent from any influence from other circadian oscillators. While all retinal cells and retinal pigment epithelium (RPE) possess circadian oscillators, these oscillators integrate by means of neural synapses, electrical coupling (gap junctions), and released neurochemicals (such as dopamine, melatonin, adenosine, and ATP), so the whole retina functions as an integrated circadian system. Dysregulation of retinal clocks not only causes retinal or ocular diseases, it also impacts the circadian rhythm of the whole body, as the light information transmitted from the retina entrains the brain clock that governs the body circadian rhythms. In this review, how circadian oscillations in various retinal cells are integrated, and how retinal diseases affect daily rhythms.
The vertebrate retina is the most unique tissue among those that display robust circadian rhythms, because it is a light sensing tissue that can “know” time through detecting the ambient illumination, but its own “circadian system” prepares the retina ready to anticipate the upcoming down or dusk. This review provides an overview on how circadian oscillations in various retinal cells are integrated, and how retinal diseases might affect daily rhythms.
We study the dark matter (DM) discovery prospect and its spin discrimination in the theoretical framework of gauge invariant and renormalizable Higgs portal DM models at the ILC with
s
=
500
GeV. In ...such models, the DM pair is produced in association with a
Z
boson. In the case of the singlet scalar DM, the mediator is just the SM Higgs boson, whereas for the fermion or vector DM there is an additional singlet scalar mediator that mixes with the SM Higgs boson, which produces significant observable differences. After careful investigation of the signal and backgrounds both at parton level and at detector level, we find the signal with hadronically decaying
Z
boson provides a better search sensitivity than the signal with leptonically decaying
Z
boson. Taking the fermion DM model as a benchmark scenario, when the DM-mediator coupling
g
χ
is relatively small, the DM signals are discoverable only for benchmark points with relatively light scalar mediator
H
2
. The spin discriminating from scalar DM is always promising, while it is difficult to discriminate from vector DM. As for
g
χ
approaching the perturbative limit, benchmark points with the mediator
H
2
in the full mass region of interest are discoverable. The spin discriminating aspects from both the scalar and the fermion DM are quite promising.
We study an extended Standard Model with a gauged U(1)′ flavor symmetry, motivated not only by the fermion mass hierarchy but also by the excesses in B→K(*)ll reported by the LHCb collaborations. The ...U(1)′ charges are assigned to quarks and leptons in a flavor-dependent manner, and flavored Higgs doublets are also introduced in order to detail the Yukawa couplings at the renormalizable level. Then, the fermion mass hierarchy is realized by the vacuum alignment of the Higgs doublets. In this model, flavor-changing currents involving the gauge boson of U(1)′ and the scalars generated by the Higgs doublets are predicted and the observables in the B→K(*)ll process possibly deviate from the Standard Model predictions. We study the possibility that these new flavor-changing interactions can explain the excesses in the B→K(*)ll process, and we derive some predictions for the other flavor-violating processes based on the analysis. We specifically investigate the ΔF=2 processes and the other B decays: e.g., B→Xsγ and B→D(*)τν, where the deviations are reported by the Belle and BABAR collaborations.
Motivated by the tensions in the Hubble constant H0 and the structure growth σ8 between Planck results and other low redshift measurements, we discuss some cosmological effects of a dark sector model ...in which dark matter (DM) interacts with fermionic dark radiation (DR) through a light gauge boson (dark photon). Such kind of models are very generic in particle physics with a dark sector with dark gauge symmetries. The effective number of neutrinos is increased by δNeff∼0.5 due to light dark photon and fermionic DR, thereby resolving the conflicts in H0. The elastic scattering between DM and DR induces suppression for DM's density perturbation, but without acoustic oscillations. For weakly-interacting DM around 100 GeV, the new gauge coupling should be ∼10−4 to have sizable effect on matter power spectrum in order to relax the tension in σ8.
We present a scale invariant extension of the standard model with a new QCD-like strong interaction in the hidden sector. A scale Λ(H) is dynamically generated in the hidden sector by dimensional ...transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale is transmitted to the SM sector by a real singlet scalar messenger S and can trigger electroweak symmetry breaking. Thus all the mass scales in this model arise from the hidden sector scale Λ(H), which has quantum mechanical origin. Furthermore, the lightest hadrons in the hidden sector are stable by the flavor conservation of the hidden sector strong interaction, and could be the cold dark matter (CDM). We study collider phenomenology, relic density, and direct detection rates of the CDM of this model.
The nature of electroweak (EW) phase transition (PT) is of great importance. It may give a clue to the origin of baryon asymmetry if EWPT is strong first order. Although it is a cross over within the ...standard model (SM), a great many extensions of the SM are capable of altering the nature. Thus, gravitational wave (GW), which is supposed to be relics of strong first order PT, is a good complementary probe to new physics beyond SM (BSM). We in this paper elaborate the patterns of strong first order EWPT in the next to simplest extension to the SM Higgs sector, by introducing a Z3-symmetric singlet scalar. We find that, in the Z3-symmetric limit, the tree level barrier could lead to strong first order EWPT either via three or two-step PT. Moreover, they could produce two sources of GW, despite of the undetectability from the first-step strong first order PT for the near future GW experiments. But the other source with significant supercooling which then gives rise to α∼O0.1 almost can be wholly covered by future space-based GW interferometers such as eLISA, DECIGO and BBO.
Search for Higgs portal DM at the ILC Ko, P.; Yokoya, Hiroshi
The journal of high energy physics,
08/2016, Letnik:
2016, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
Higgs portal dark matter (DM) models are simple interesting and viable DM models. There are three types of the models depending on the DM spin: scalar, fermion and vector DM models. In this ...paper, we consider renormalizable, unitary and gauge invariant Higgs portal DM models, and study how large parameter regions can be surveyed at the International Linear Collider (ILC) experiment at
s
=
500
GeV. For the Higgs portal singlet fermion and vector DM cases, the force mediator involves two scalar propagators, the SM-like Higgs boson and the dark Higgs boson. We show that their interference generates interesting and important patterns in the mono-
Z
plus missing
E
T
signatures at the ILC, and the results are completely different from those obtained from the Higgs portal DM models within the effective field theories. In addition, we show that it would be possible to distinguish the spin of DM in the Higgs portal scenarios, if the shape of the recoil-mass distribution is observed. We emphasize that the interplay between these collider observations and those in the direct detection experiments has to be performed in the model with renomalizability and unitarity to combine the model analyses in different scales.
We propose a novel particle physics model in which vector dark matter (VDM) and dark radiation (DR) originate from the same non-Abelian dark sector. We show an illustrating example where dark SU(3) ...is spontaneously broken into SU(2) subgroup by the nonzero vacuum expectation value (VEV) of a complex scalar in fundamental representation of SU(3). The massless gauge bosons associated with the residual unbroken SU(2) constitute DR and help to relieve the tension in Hubble constant measurements between Planck and Hubble Space Telescope. In the meantime, massive dark gauge bosons associated with the broken generators are VDM candidates. Intrinsically, this non-Abelian VDM can interact with non-Abelian DR in the cosmic background, which results in a suppressed matter power spectrum and leads to a smaller σ8 for structure formation.
We propose a predictive radiative seesaw model at one-loop level with a flavor dependent gauge symmetry U(1)xB3−xe−μ+τ and Majorana fermion dark matter. For the neutrino mass matrix, we obtain an A1 ...type texture (with two zeros) that provides us several predictions such as the normal ordering for the neutrino masses. We analyze the constraints from lepton flavor violations, relic density of dark matter, and collider physics for the new U(1)xB3−xe−μ+τ gauge boson. Within the allowed region, the LHCb anomalies in B→K⁎μ+μ− and B→Kℓ+ℓ− with ℓ=e or μ can be resolved, and such Z′ could be also observed at the LHC.
We consider a minimal renormalizable and gauge invariant dark matter (DM) model, in which the singlet fermion DM has only axial couplings to a new pseudoscalar mediator. The mixing between the ...pseudoscalar mediator and the standard model (SM) Higgs boson induces the interactions between the DM and SM particles. The DM candidate in this model can provide the correct thermal relic density and evades all direct detections, while it can produce observable signals in indirect detection experiments due to its large annihilation cross section. A comparative study for DM phenomenology at the LHC is conducted for models with scalar mediators that have either scalar or pseudoscalar couplings to SM particles and the DM. We find that the three scenarios have distinguishable features in scalar decay branching ratio, DM pair production cross section as well as the signal reaches at the LHC. The LHC searches for some visible signals related to the scalar sector are also discussed.
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