Hi Stavros,
Both α and β are ratios that can range from 0 to infinity, with extreme values being 0.01 and 100. These values 0.01 and 100 are considered equally extreme.
The α parameter balances between data consistency and rotation equivariance, while β determines the level of denoising to be applied during training. By default, α is set to 1 and β to 0.5. Supplementary Figure 1 provides examples of different values.
A larger α generally results in smoother outcomes. However, very small values, such as 0.1, might lead to overcompensation. While it is challenging to determine the optimal α, starting with the default value of 1 is probably good. (Think about balancing Tau value in RELION)
For β, the goal is to achieve effective denoising, larger means more denoising. In a slice view of the map, a good β value is indicated by suppressed background noise while preserving the structure.
I hope these help.