Speaker
Description
We explore a new kind of NLED field as a source of gravity, which can accelerate the universe during the inflationary era. We propose a new type of NLED lagrangian which is characterized by two parameters: α (dimensionless parameter) and β (dimensionful parameter). We investigate the classical stability and the causality aspects of this model of inflationary expansion by demanding that the speed of the sound wave c_s^2 > 0 and 0 ≤ c_s^2 ≤ 1. Corresponding to 0 ≤ c_s^2 ≤ 1, we find 0.382(1.828) ≤ βB 2 ≤ 0.288(1.469) for α = 0.1(1.0). The equation of state parameter ω = −1/3 requires β_B^2 = 0.126(0.757) corresponding to α = 0.1(1.0). We find that the universe is accelerating i.e. ä > 0 (which results in the deceleration parameter q < 0 (i.e. ω > −1/3)), provided β_B^2 ≥ 0.126(0.757). During inflation, the energy density ρ_B is found to be maximum and = 0.65/β. The magnetic field necessary to trigger the inflation is found to be B ' is given by B_max = 4 × 10^51 Gauss. Our model also predicts the e-fold number N = 71(64) that the magnetic field at the end of inflation is about B = 10^{−10} (10^{−4} ) Gauss corresponding to z = 0(1000) and this agrees quite well with the experimental prediction of the e-fold number. With α = 0.3(1.0) and β_B^2 = 0.3974(0.8239), we find the scalar spectral index n_s = 0.9649, consistent with the PLANCK 2018 CMB data. Further, with α = 0.3(1.0), β_B^2 = 0.3974(0.8239), we predicts the tensor-to-scalar ratio r = 0.1417(0.1449) and the tensorial spectral index n_T = −0.0177(−0.0181). Journal Reference: Physica Scripta. 96, 065305 (2021).
