20 research outputs found
Adiabatic out-of-equilibrium solutions to the Boltzmann equation in warm inflation
We show that, in warm inflation, the nearly constant Hubble rate and
temperature lead to an adiabatic evolution of the number density of particles
interacting with the thermal bath, even if thermal equilibrium cannot be
maintained. In this case, the number density is suppressed compared to the
equilibrium value but the associated phase-space distribution retains
approximately an equilibrium form, with a smaller amplitude and a slightly
smaller effective temperature. As an application, we explicitly construct a
baryogenesis mechanism during warm inflation based on the out-of-equilibrium
decay of particles in such an adiabatically evolving state. We show that this
generically leads to small baryon isocurvature perturbations, within the bounds
set by the Planck satellite. These are correlated with the main adiabatic
curvature perturbations but exhibit a distinct spectral index, which may
constitute a smoking gun for baryogenesis during warm inflation. Finally, we
discuss the prospects for other applications of adiabatically evolving
out-of-equilibrium states.publishe
Massively parallel simulations of relativistic fluid dynamics on graphics processing units with CUDA
Relativistic fluid dynamics is a major component in dynamical simulations of the quark–gluon plasma created in relativistic heavy-ion collisions. Simulations of the full three-dimensional dissipative dynamics of the quark–gluon plasma with fluctuating initial conditions are computationally expensive and typically require some degree of parallelization. In this paper, we present a GPU implementation of the Kurganov–Tadmor algorithm which solves the 3 + 1d relativistic viscous hydrodynamics equations including the effects of both bulk and shear viscosities. We demonstrate that the resulting CUDA-based GPU code is approximately two orders of magnitude faster than the corresponding serial implementation of the Kurganov–Tadmor algorithm. We validate the code using (semi-)analytic tests such as the relativistic shock-tube and Gubser flow