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- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
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| 3. |
- Ahdida, C., et al.
(författare)
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Sensitivity of the SHiP experiment to dark photons decaying to a pair of charged particles
- 2021
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:5
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Tidskriftsartikel (refereegranskat)abstract
- Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon m(gamma)D and its mixing parameter with the photon, epsilon. The sensitivity of the SHiP detector is reviewed for dark photons in the mass range between 0.002 and 10 GeV. Different productionmechanisms are simulated, with the dark photons decaying to pairs of visible fermions, including both leptons and quarks. Exclusion contours are presented and compared with those of past experiments. The SHiP detector is expected to have a unique sensitivity for m. D ranging between 0.8 and 3.3(-0.5)(+0.2) GeV, and epsilon(2) ranging between 10(-11) and 10(-17).
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| 4. |
- Ahdida, C., et al.
(författare)
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Sensitivity of the SHiP experiment to light dark matter
- 2021
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :4
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Tidskriftsartikel (refereegranskat)abstract
- Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopting the benchmark scenario for light dark matter particles produced in the decay of a dark photon, with αD = 0.1 and mA′ = 3mχ, we study the potential of the SHiP experiment to detect such elusive particles through its Scattering and Neutrino detector (SND). In its 5-years run, corresponding to 2 · 1020 protons on target from the CERN SPS, we find that SHiP will improve the current limits in the mass range for the dark matter from about 1 MeV to 300 MeV. In particular, we show that SHiP will probe the thermal target for Majorana candidates in most of this mass window and even reach the Pseudo-Dirac thermal relic.
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| 5. |
- Sakatani, N., et al.
(författare)
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Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body
- 2021
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Ingår i: Nature Astronomy. - : Springer Nature. - 2397-3366. ; 5:8, s. 766-774
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Tidskriftsartikel (refereegranskat)abstract
- Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4,5,6), higher than meteorites but lower than cometary nuclei7, which are considered to be remnants of the original planetesimals8. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters (<20 m in diameter), boulders with reflectance (~0.015) lower than the Ryugu average6 and porosity >70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment9 is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction3. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations10,11.
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| 9. |
- Rizwan, M., et al.
(författare)
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Photochemically Activated Notch Signaling Hydrogel Preferentially Differentiates Human Derived Hepatoblasts to Cholangiocytes
- 2021
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31:5, s. 2006116-
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Tidskriftsartikel (refereegranskat)abstract
- Cholangiocytes form an intricate network of bile ducts to enable proper liver function; yet, recapitulating human stem cell differentiation to cholangiocytes in vitro requires Notch signaling and soluble ligands do not activate the Notch pathway. To overcome these limitations, jagged1 is immobilized on a chemically defined hyaluronan to specifically differentiate human embryonic stem cell-derived hepatoblasts to cholangiocytes. Hepatoblasts cultured on the jagged1-hydrogels upregulate Notch target genes and express key cholangiocyte markers including cystic fibrosis transmembrane conductance regulator. Moreover, cholangiocytes adopt morphological changes that resemble liver biliary structures. To emulate natural biliary system development, a new strategy is developed to achieve spatiotemporal control over the Jagged1–Notch2 interaction: jagged1 is first caged with a photocleavable streptavidin and then it is uncaged photochemically to restore the biological function of Jagged1, which is confirmed with Notch2 activation in a fluorescent reporter cell line. Moreover, the differentiation of human embryonic stem cell-derived hepatoblasts to cholangiocytes is temporally controlled with photochemical uncaging of this streptavidin-Jagged1-immobilized hyaluronan hydrogel. This strategy defines a framework to control protein signaling in time and space and specifically for Notch signaling for ultimate use in regenerative medicine strategies of the liver.
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