An effective approach to same sign top pair production at the LHC and   the forward-backward asymmetry at the Tevatron
  We study the phenomenology of same sign top pair production at the LHC in a model-independent way. The complete set of dimension six operators involving two top (or anti-top) quarks is introduced and the connection with all possible t- or s-channel particle exchanges is established. Only in the former case, same and opposite sign top pair production can be related. We find that while current Tevatron data disfavor t-channel models, other production mechanisms are viable and can be tested at the LHC. 
Celine Degrande, Jean-Marc Gerard, Christophe Grojean, Fabio Maltoni,   Geraldine Servant
hep-ph hep-ex