Formation of gas giant systems

arXiv:0808.1439 [astro-ph]: Gas disks to gas giants: Simulating the birth of planetary systems
Massive discs form gas giants early, which migrate inwards and produce hot Jupiters. Low mass discs form lots of smaller ice giant type planets. In both cases, planets often end up packed closely together which sets things up for planet-planet scattering after the disc dissipates.

Solar system analogues are predicted to be rare.