Related papers: Entropy Production in a Lepton-Photon Universe
The cosmological entropy production is studied in the (1+3+6)-dimensional space-times consisting of the outer space (the 3-dimensional expanding section) and the inner space (the 6-dimensional section). The inner space expands initially and…
We propose a novel leptogenesis mechanism with a temperature-dependent coupling between the right-handed neutrino and Standard Model particles. This coupling experiences suppression at high temperatures and becomes sizable when the lepton…
We reconsider the evolution of strongly degenerate neutrinos in the early universe. Our chief concern is the validity of the entropy conservation after the neutrino annihilation process has frozen out (so that the establishment of chemical…
In this work, we extend our previous study of the bulk viscosity of hot and dense $npe$ matter induced by the Urca processes in the neutrino trapped regime to $npe\mu$ matter by adding the muonic Urca processes as well as the purely…
Gravitino production and decay in the inflationary universe are reexanimed. Assuming that gravitino mainly decays into photon and photino, we have calculated the upperbound of the reheating temperature. Compared to previous works, we have…
Microseconds after the Big Bang quarks and gluons formed a strongly-coupled non-conformal liquid driven out-of-equilibrium by the expansion of the Universe. We use holography to determine the non-equilibrium behavior of this liquid in a…
We study bulk viscosity arising from weak current Urca processes in dense baryonic matter at and beyond nuclear saturation density. We consider the temperature regime where neutrinos are trapped and therefore have nonzero chemical…
Gravitino production and decay in the inflationary universe are reexamined. Assuming that the gravitino mainly decays into a photon and a photino, we calculate the upperbound on the reheating temperature. Compared to previous works, we have…
In many realizations of leptogenesis, heavy right-handed neutrinos play the main role in the generation of an imbalance between matter and antimatter in the early Universe. Hence, it is relevant to address quantitatively their dynamics in a…
In this work, we use the Gouy-Stodola theorem to calculate the entropy production rate in the inflationary epoch of the universe. This theorem allows us the simple calculation of entropy and entropy production rate occasioned by the…
Recently, it has been shown that the presence of a non-instantaneous era of reheating can significantly alter the charged lepton(s) equilibration temperature(s) which plays important role in flavor leptogenesis. In this work, we extend the…
Production of lepton pairs in gamma p -> e-e+ p reaction is studied at photon energies up to 1 GeV. We show that even if lepton charge is not measured there are extensive kinematical regimes where the nuclear process dominates over the…
It is shown that the vacuum-like energy of the Higgs potential at non-zero temperatures leads, in the course of the cosmological expansion, to a small but non-negligible rise of the entropy density in the comoving volume. This increase is…
The observed baryon asymmetry of the Universe is suitably created in thermal leptogenesis through the out-of-equilibrium decay of $N_1$, the lightest of the three heavy singlet neutral fermions which anchor the seesaw mechanism to obtain…
There exists the "entropy problem" of the early universe, that is, why did the universe begin with an extremely low entropy and how did it evolve into such high entropy at late times? It has been long believed that inflation cannot be the…
A large lepton asymmetry could be generated in the Early Universe by oscillations of active to sterile neutrinos with a small mixing angle sin 2 \theta < 10^-2. The final order of magnitude of the lepton asymmetry \eta is mainly determined…
During inflation, scalar fields, including the Higgs boson, may acquire a nonzero vacuum expectation value, which must later relax to the equilibrium value during reheating. In the presence of the time-dependent condensate, the vacuum state…
If neutrinos are Dirac particles and their right-handed component can be copiously produced in the early universe, then they could influence a direct observation of the cosmic neutrino background, which, most likely, will come about with…
The present work deals with a cosmological model having particle creation mechanism in the framework of irreversible thermodynamics. In the second order non-equilibrium thermodynamical prescription, the particle creation rate is treated as…
We consider an extended version of superconformal subcritical hybrid inflation model by introducing three right-handed neutrinos that have the Majorana mass terms. In the model one of the right-handed sneutrinos plays a role of the inflaton…