Multi-field oscillons/I-balls in the Friedberg-Lee-Sirlin model

Abstract

We study oscillon/I-ball solutions in a real scalar version of the Friedberg-Lee-Sirlin (FLS) model. Using the two-timing analysis, we derive the conditions for oscillon solutions and explore multi-field oscillon configurations. In these configurations, the two fields form co-located oscillons that oscillate with frequencies set by their respective masses. These multi-field oscillons can be viewed as a bound state of two oscillons due to attractive interactions between the fields. We confirm these analytical predictions through numerical lattice calculations. This work extends the standard picture of single-field oscillons and may be relevant for cosmological scenarios involving multiple interacting real scalar fields.

Figures (6)

• Figure 1: Spatial profiles of single-field oscillons for $\phi$ (left) and $\psi$ (right).
• Figure 2: Parameter regions with an extrema of $U_\mathrm{eff}$ at $0 < \theta < \pi/2$. The red and blue regions denote positive and negative extremum values of $U_\mathrm{eff}$, respectively.
• Figure 3: Spatial profiles of multi-field oscillons for $\omega_\varphi= \omega_\psi = 1$ and various values of $\mu$.
• Figure 4: Snapshots of the energy density from the lattice simulation with random initial conditions for $\mu = \sqrt{0.2}$.
• Figure 5: Snapshot of field configurations from a lattice simulation with random initial conditions. The solid lines denote the results of the lattice simulation, while the dashed lines denote the solution obtained from the two-timing analysis, where $X \equiv a(t)x$ is the physical length.