Quenching preheating by light fields

In this paper we investigate the role of additional light fields not directly coupled to the background during preheating. We extend our previous study that proved that the production of particles associated with such fields can be abundant due to quantum corrections, even for the massless states. We also obtain the expression for the occupation number operator in terms of interacting fields, which includes the nonlinear effects important for nonperturbative particle production. We show that adding too many light degrees of freedom without direct interactions with the background might attenuate or even quench preheating as the result of backreaction effects and quantum corrections.

Figure 1

Time evolution of the number density of produced states for $g=0.1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, and $\dot{\varphi }(t=0)=0$ in the two-scalar system. The scale $M\sim 0.04M_{PL}$, where $M_{PL}$ denotes the Planck mass $M_{PL}\sim 1.22\times 10^{19}\mathrm{GeV}$, is chosen to be close to the unification scale and allows us to stay in agreement with the observational data.

Figure 2

Time spent by the trajectory in the adiabatic region in comparison with the Hubble time.

Figure 3

Time evolution of the number density of produced states in the system with an additional light sector for $g=0.1$, $y=1$, $n=1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, and $\dot{\varphi }(t=0)=0$.

Figure 4

Envelope of the time evolution of the background $⟨\varphi ⟩$ for $g=0.1$, $y=1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, and $\dot{\varphi }(t=0)=0$ for different numbers of additional light fields: 1, 2, 5, and 7.

Figure 5

Time evolution of the number density of produced states $\chi$, $\varphi$, and $\xi$ for $g=0.1$, $n=1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, $\dot{\varphi }(t=0)=0$, and different values of $y$ coupling. The values $y=0.7$ and $y=1$ correspond to quenching of parametric resonance.

Figure 6

Envelope of the time evolution of the background $⟨\varphi ⟩$ for $g=0.1$, $n=1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, $\dot{\varphi }(t=0)=0$, and different values of $y$ coupling. For $y=0.7$ and $y=1$ we can observe the quenching of the preheating.

Figure 7

Comparison between time evolution of the number density of produced states (upper) and the background $⟨\varphi ⟩$ (lower) obtained with new and old methods for $g=1$, $m_{\varphi }=0.001M$, $\varphi (t=0)=M$, and $\dot{\varphi }(t=0)=0$. New denotes the interacting theory described here and old denotes the asymptotic approximation presented in [14].