Related papers: Entropy Production in a Lepton-Photon Universe
We look at viscosity production in a universe consisting purely of leptons and photons. This is quite close to what the Universe actually look like when the temperature was between $10^{10}$ K and $10^{12}$ K ($1$ -- $100$ MeV). By taking…
Small Recent theories have proposed a variety of massive particles, like the moduli, whose abundance or decay endangers standard cosmological results. To dilute them, thermal inflation has been proposed, with its own massive scalar flaton…
Late-time entropy production from scalar decay arises in scenarios like thermal inflation, proposed to dilute long-lived, massive fields like the gravitino and the moduli. The scalar decay may continue into Mev-scale temperatures and affect…
The late-time entropy production by the massive particle decay induces the various cosmological effects in the early epoch and modify the standard scenario. We investigate the thermalization process of the neutrinos after the entropy…
We show that a phase transition may take place in the early Universe at a temperature $T_*$ via a Standard Model singlet scalar field which happens to couple to right handed neutrinos (RHN) resulting a temperature dependent mass for them…
We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy. We show that neutrinos can begin to decouple at higher temperatures than previous estimates due to several corrections…
We investigate cosmological effects concerning the late-time entropy production due to the decay of non-relativistic massive particles. The thermalization process of neutrinos after the entropy production is properly solved by using the…
Entropy production from scalar decay in the era of low temperatures after neutrino decoupling will change the ratio of the relic neutrino temperature to the CMB temperature, and, hence, the value of N_eff, the effective number of neutrino…
We perform calculations of dark photon production and decay in the early universe for ranges of dark photon masses and vacuum coupling with standard model photons. Simultaneously and self-consistently with dark photon production and decay,…
We evaluate entropy production in a photovoltaic cell that is modeled by four electronic levels resonantly coupled to thermally populated field modes at different temperatures. We use a formalism recently proposed, the so-called multiple…
A calculation of neutrino decoupling in the early Universe, including full Fermi-Dirac statistics and electron mass dependence in the weak reaction rates, is presented. We find that after decoupling, the electron neutrinos contribute 0.83\%…
Many models possess unwanted relics, which should be diluted by entropy production just before the big-bang nucleosynthesis. A field responsible for the entropy production may produce stable weakly interacting massive particles, if…
The thermodynamic behavior of a decaying vacuum cosmology describing the entire cosmological history evolving between two extreme (early and late time) de Sitter eras is investigated. The thermal evolution from the early de Sitter to the…
Leptogenesis is studied within the seesaw neutrino mass model in a regime where all sterile neutrinos have prompt rather than delayed decays. It is shown that during neutrino thermal production lepton asymmetries are generated in both…
We point out that in the early universe, for temperatures in the approximate interval 175-80 MeV (after the quark-gluon plasma), pions carried a large share of the entropy and supported the largest inhomogeneities. Thus, we examine the…
We investigate the leptogenesis via decays of heavy Majorana neutrinos which are produced non-thermally in inflaton decays. We make a comprehensive study on the leptogenesis assuming various supersymmetric (SUSY) models for hybrid, new and…
We show that the reheating temperature of a matter-domination era in the early universe can be pushed down to the neutrino decoupling temperature at around $2 \ {\rm MeV}$ if the reheating takes place through non-hadronic decays of the…
The production rate of heavy Majorana neutrinos is relevant for models of thermal leptogenesis in the early Universe. In the high temperature limit the production can proceed via the 1 <-> 2 (inverse) decays which are allowed by the thermal…
We investigate in detail the leptogenesis by the decay of coherent right-handed sneutrino $\widetilde{N}$ having dominated the energy density of the early universe, which was originally proposed by HM and TY. Once the $\widetilde{N}$…
Entropy production during the process of thermal phase-separation of multiphase flows is investigated by means of a discrete Boltzmann kinetic model. The entropy production rate is found to increase during the spinodal decomposition stage…