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We discuss how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction. A larger ratio of the sound horizon to the photon diffusion length follows, implying a smaller inferred Neff. This neutrino-mass/recombination effect depends strongly on the neutrino rest masses. Though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving an observational handle of neutrino mass physics.
We investigate whether right-handed neutrinos can play the role of the dark matter of the Universe and be generated by the freeze-out production mechanism. In the standard picture, the requirement of a long lifetime of the right-handed neutrinos impl
We investigate the kinetic freeze out scenario of a nucleon gas through a finite layer. The in-medium mass modification of nucleons and its impact on the freeze out process is studied. A considerable modification of the thermodynamical parameters tem
Atoms and molecules, and in particular CO, are important coolants during the evolution of interstellar star-forming gas clouds. The presence of dust grains, which allow many chemical reactions to occur on their surfaces, strongly impacts the chemical
We consider Tsallis cosmology as an approach to thermodynamic gravity and derive the bound on the Tsallis parameter to be $beta<2$ by using the constraints derived from the formation of the primordial light elements, Helium, Deuterium and Litium, fro
We present STAR results from identified particle spectra measured in $sqrt{s_{NN}}$ = 62.4 GeV Au-Au collisions. Particle production and system dynamics are compared to results at $sqrt{s_{NN}}$ = 200 GeV. We extract kinetic and chemical freeze-out p