In Situ Models for Planet Assembly around Cool stars
  We present a model for the in situ assembly of planetary systems around a 0.5~$M_{\odot}$ star, and compare the resulting statistics to the observed sample of cool Kepler planet candidates from Dressing & Charbonneau (2013). We are able to reproduce the distribution of planetary periods and period ratios, although we once again find an underabundance of single transit systems relative to the observations. We also demonstrate that almost every planetary system assembled in this fashion contains at least one planet in the habitable zone, and that water delivery to these planets can potentially produce a water content comparable to that of Earth. Our results broadly support the notion that habitable planets are plentiful around M~dwarfs in the solar neighbourhood. 
Brad M. S. Hansen
astro-ph.EP