Rutger H. Boels and Tobias Hansen of DESY, Hamburg released a very interesting 66-page-long hep-th preprint today,
Slightly off-topic. Congratulations to Joe Polchinski who will be 60 in the spring but who already has the Joefest now; see Clifford Johnson and Matt Strassler. If you need a higer-res version of the picture, let me know.
One may say – and they probably say – that they're returning to the mode of reasoning that existed shortly after the birth of string theory (the publication of the Veneziano amplitude) before it was shown that Veneziano's amplitude followed from a theory of strings.