About this Research Topic
Cold dark matter(CDM) and dark energy(DE) constitute roughly 27% and 68%, respectively, of the energy density of the Universe. The baryons constitute only 4.5%--5.0%, but it is the most well established one among these through the nucleosynthesis theory in calculating the primordial abundances of light elements, Helium-4, Deuterium, Helium-3, Lithium-7, Berilium-7, etc., with the input net baryon number fraction of (0.47-0.65)x10**{-9} times the critical energy density, which agrees with the observation. On the other hand, the natures on CDM and DE have not been confirmed yet. Therefore, probing what is the CDM particle(s) and how the present DE has emerged in the recent history of the Universe will be of the prime activity in the early cosmology research, both in model building and in detection method. With the discovery of the Higgs-Brout-Englert-Guralnik-Hagen-Kibble(HBEGHK) boson, which is the first experimental discovery on the fundamental scalar particles, the fundamental scalars will be extensively used in the CDM research.
In the research topic on the ``bosonic coherent motion(BCM) in the Universe evolution", CDM from the harmonic oscillation of coherent bosons, collectively moving together with the same phase, and the related issues will be scrutinized both theoretically and experimentally. The most well-known BCM for CDM in the Universe evolution is the coherent axion-oscillation. For the coherent axion CDM, its mass and interaction strengths are more or less related and hence a definite mass can be given, leading to the axion lifetime greater than the age of the Universe for m_a<24 eV. Other fundamental scalars with appropriate potentials may work also as CDM candidates. Under the name of 'quintessence', fundamental scalars have been already suggested for the DE domination in the recent history of the Universe. However, there has not emerged a single most attractive quintessence model yet, and the research on DE with fundamental scalars will get momentum with the HBEGHK boson discovery.
The on-going experiments looking for BCM as a CDM candidate are mostly the Sikivie-type cavity detectors. Because of its limited range of operation, for example only the mico-eV range in case of axions, other feasible experimental ideas are welcome in detecting the BCM. For detecting DE, fresh new ideas beyond the by-gone history of the cosmological evolution may be needed.
In the research topic on the ``bosonic coherent motion(BCM) in the Universe evolution", CDM from the harmonic oscillation of coherent bosons, collectively moving together with the same phase, and the related issues will be scrutinized both theoretically and experimentally. The most well-known BCM for CDM in the Universe evolution is the coherent axion-oscillation. For the coherent axion CDM, its mass and interaction strengths are more or less related and hence a definite mass can be given, leading to the axion lifetime greater than the age of the Universe for m_a<24 eV. Other fundamental scalars with appropriate potentials may work also as CDM candidates. Under the name of 'quintessence', fundamental scalars have been already suggested for the DE domination in the recent history of the Universe. However, there has not emerged a single most attractive quintessence model yet, and the research on DE with fundamental scalars will get momentum with the HBEGHK boson discovery.
The on-going experiments looking for BCM as a CDM candidate are mostly the Sikivie-type cavity detectors. Because of its limited range of operation, for example only the mico-eV range in case of axions, other feasible experimental ideas are welcome in detecting the BCM. For detecting DE, fresh new ideas beyond the by-gone history of the cosmological evolution may be needed.
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