Constraints on Genesis Cosmology from the Smeared Null Energy Condition

Abstract

The violation of the null energy condition (NEC) is essential for constructing nonsingular cosmological scenarios, such as Genesis cosmology, which avoids the initial singularity by initiating cosmic evolution from an asymptotically Minkowski state. To address theoretical concerns regarding the accumulation of negative energy, the smeared null energy condition (SNEC) has been proposed as a quantum-motivated, semi-local bound on NEC violation. In this work, we examine the implications of the SNEC conjecture for Genesis models, typically constructed within generalized Galileon theories. Our results demonstrate that SNEC imposes nontrivial restrictions on the viability of Genesis models, highlighting the SNEC conjecture as a powerful tool for constraining nonsingular cosmological scenarios.

Figures (6)

• Figure 1: The SNEC constraints with $B=1/(32\pi)$ and $M=0.9$ fixed. The shaded regions represent the parameter space in which the SNEC is violated.
• Figure 2: The SNEC constraints with $\bar{t}$ and $M$ fixed (left channel), and with $\bar{t}$ and $B$ fixed (right channel). The shaded regions represent the parameter space in which the SNEC is violated.
• Figure 3: The SNEC constraints with $\bar{t} = -50000$ and $B = 1/(32\pi)$. The labels "G" and "L" in parentheses indicate the use of Gaussian and Lorentzian smearing functions, respectively. The shaded regions represent the parameter space in which the SNEC is violated.
• Figure 4: The SNEC constraints with $B = 1/(32\pi)$, $M = 0.9$ and $\bar{t} = -500$ fixed. The shaded regions indicate the parts of parameter space in which the SNEC is violated.
• Figure 5: The SNEC constraints with $B = 1/(32\pi)$, $M = 0.9$ and $\Delta t=250$ fixed. The shaded regions indicate the parts of parameter space in which the SNEC is violated.