Improved upper bounds are presented on the coupling |Ue4|2 of an electron to a sterile neutrino ν4 from analyses of data on nuclear and particle decays, including superallowed nuclear beta decays, ...the ratios Re/μ(π)=BR(π+→e+νe)/BR(π+→μ+νμ), Re/μ(K), Re/τ(Ds), and Be2+ decay, covering the mass range from MeV to GeV.
A detailed discussion is given of the analysis of recent data to obtain improved upper bounds on the couplings |Ue4|2 and |Uμ4|2 for a mainly sterile neutrino mass eigenstate ν4. Using the excellent ...agreement among the Ft values (products of kinematic rate factors times half-lives with radiative corrections included) for superallowed nuclear beta decays, an improved upper limit is derived for emission of a ν4. The agreement of the ratios of branching ratios Re/μ(π) = BR(π+ → e+νe)/BR(π+ → μ+νμ), Re/μ(K), Re/τ(Ds), Rμ/τ(Ds), and Re/τ(D), and the branching ratios BR(B+ → e+νe) and BR(B+ → μ+νμ) decays with predictions of the Standard Model is utilized to derive new constraints on ν4 emission covering the ν4 mass range from MeV to GeV. We also discuss constraints from peak search experiments probing for emission of a ν4 via lepton mixing, as well as constraints from pion beta decay, CKM unitarity, μ decay, leptonic τ decay, and other experimental inputs.
A search for massive neutrinos has been made in the decay π+→e+ν. No evidence was found for extra peaks in the positron energy spectrum indicative of pion decays involving massive neutrinos (π→e+νh). ...Upper limits (90% C.L.) on the neutrino mixing matrix element |Uei|2 in the neutrino mass region 60–135 MeV/c2 were set and are an order of magnitude improvement over previous results.
A new measurement of the branching ratio R_{e/μ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→μ^{+}ν+π^{+}→μ^{+}νγ) resulted in R_{e/μ}^{exp}=1.2344±0.0023(stat)±0.0019(syst)×10^{-4}. This is in agreement ...with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.
The three body pion decays ... where X is a weakly interacting neutral boson, were searched for using the full data set from the PIENU experiment. An improved limit on ... in the mass range ... and a ...first result for ... in the region ... were obtained. The Majoron-neutrino coupling model was also constrained using the current experimental result of the ... branching ratio.(ProQuest: ... denotes formulae omitted.)
In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays π+→μ+ν at rest by examining the observed muon energy spectrum for extra peaks in addition to the expected peak ...for a light neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix |Uμi|2 in the neutrino mass region of 15.7–33.8 MeV/c2, improving on previous results by an order of magnitude.
Charged lepton flavor violating muon decay μ+ → e+XH, where XH is a massive neutral boson, was sought by searching for extra peaks in the muon decay μ+ → e+ν¯ν energy spectrum in the mXH mass region ...47.8–95.1 MeV/c2. No signal was found and 90% confidence level upper limits were set on the branching ratio Γ(μ+ → e+XH)/Γ(μ+ → e+ν¯ν) at the level of 10−5 for this region.
High-acuity vision in primates, including humans, is mediated by a small central retinal region called the fovea. As more accessible organisms lack a fovea, its specialized function and its ...dysfunction in ocular diseases remain poorly understood. We used 165,000 single-cell RNA-seq profiles to generate comprehensive cellular taxonomies of macaque fovea and peripheral retina. More than 80% of >60 cell types match between the two regions but exhibit substantial differences in proportions and gene expression, some of which we relate to functional differences. Comparison of macaque retinal types with those of mice reveals that interneuron types are tightly conserved. In contrast, projection neuron types and programs diverge, despite exhibiting conserved transcription factor codes. Key macaque types are conserved in humans, allowing mapping of cell-type and region-specific expression of >190 genes associated with 7 human retinal diseases. Our work provides a framework for comparative single-cell analysis across tissue regions and species.
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•Macaque fovea and peripheral retina each contain >65 cell types•Most types correspond between regions but differ in proportions and gene expression•Greater conservation of interneuron than ganglion cell types between macaque and mouse•Cell-type- and region-specific expression of genes implicated in human blindness
Single-cell-based analysis provides a comprehensive molecular and cellular taxonomy of the primate retina.
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