Related papers: Viscosity in a Lepton-Photon Universe
We present a discussion of the effects induced by the bulk viscosity on the very early Universe stability. The matter filling the cosmological (isotropic and homogeneous) background is described by a viscous fluid having an…
We discuss the bulk viscosity of hot and dense $npe\mu$ matter arising from weak-interaction direct Urca processes. We consider two regimes of interest: (a) the neutrino-transparent regime with $T\leq T_{\rm tr}$ ($T_{\rm tr}\simeq 5\div…
We explore the viability of a bulk viscous matter-dominated Universe to explain the present accelerated expansion of the Universe. The model is composed by a pressureless fluid with bulk viscosity of the form \zeta = \zeta_0 + \zeta_1 * H…
The full causal M\"uller-Israel-Stewart (MIS) theory of dissipative processes in relativistic fluids is applied to a flat, homogeneous and isotropic universe with bulk viscosity. It is clarified in which sense the so called truncated…
Cosmic-rays with energies up to $3\times10^{20}$ eV have been observed, as have as have astrophysical neutrinos with energies above 1 PeV. In this talk, I will discuss some of the unique phenomena that occur when particles with TeV energies…
In this paper, we discuss the damping of density oscillations in dense nuclear matter in the temperature range relevant to neutron star mergers. This damping is due to bulk viscosity arising from the weak interaction ``Urca'' processes of…
The gravitino may well play an important role in cosmology, not only because its interactions are Planck-suppressed and therefore long-lived, but also because it is copiously produced via various processes such as particle scatterings in…
We study viscosity of the neutron star matter and $r$-mode instability in rotating neutron stars. Contributions to the shear and bulk viscosities from various processes are calculated with account of in-medium modifications of the…
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 point out a new effect on the freeze-out process of heavy particles induced by density perturbations in the early universe, which we call ``acoustically driven freeze-out.'' This beyond-linear effect is caused by the exponential…
We study the bulk viscosity of a pion gas in unitarized Chiral Perturbation Theory at low and moderate temperatures, below any phase transition to a quark-gluon plasma phase. We argue that inelastic processes are irrelevant and…
Recent work [B. Fore and S. Reddy, Phys. Rev. C 101 035809 (2020)] has shown that the population of thermal pions could modify the equation of state and transport properties of hot and dense neutron-rich matter and introduce new reaction…
We study the impact for leptogenesis of new U(1) gauge bosons coupled to the heavy Majorana neutrinos. They can significantly enhance the efficiency of thermal scenarios in the weak washout regime as long as the Z' masses are not much…
The gravitino problem is revisited in the framework of cosmological models in which the primordial cosmic matter is described by a relativistic imperfect fluid. Dissipative effects (or bulk viscosity effects) arise owing to the different…
We discuss the dynamical effects of bulk viscosity and particle creation on the early evolution of the Friedmann -Robertson -Walker model in the framework of open thermodynamical systems. We consider bulk viscosity and Particle creation as…
We consider a rotating neutron star with the presence of hyperons in its core, using an equation of state in an effective chiral model within the relativistic mean field approximation. We calculate the hyperonic bulk viscosity coefficient…
In this talk, we discuss one of the dissipative processes which likely take place in the Early Universe. We assume that the matter filling the isotropic and homogeneous background is to be described by a relativistic viscous fluid…
Thermal leptogenesis induced by the CP-violating decay of a right-handed neutrino (RHN) is discussed in the background of quintessential kination, i.e., in a cosmological model where the energy density of the early Universe is assumed to be…
Gravitational production of massive particles due to cosmic expansion can be significant during the inflationary and reheating period of the Universe. If the particle also has non-gravitational interactions that do not significantly affect…
We study the bulk viscosity in neutron star cores due to modified Urca processes involving nucleons, electrons and muons and analize its reduction by singlet-state or triplet-state superfluidity of nucleons. In combination with the results…