Inflation and B-L breaking scale
  Inflation arises in supersymmetric grand unified theories (susy GUTs) without fine tuning and cosmic strings usually form at the end of inflation. Hence both strings and inflation contribute to the density perturbations in the very early universe which lead to structure formation and to CMB anisotropies. This may give us a hint as to the $B-L$ breaking scale. 
R. Jeannerot (CTP, University of Sussex, UK)