Deliberations on 11D superspace for the M-theory effective action

In relation to the superspace modifications of 11D supergeometry required to describe the M-theory low-energy effective action, we present an analysis of infinitesimal supergravity fluctuations about the flat superspace limit. Our investigation confirms Howeʹs interpretation of our previous Bianchi identity analysis. However, the analysis also shows that should 11D supergravity obey the rules of other off-shell supergravity theories, the complete M-theory corrections will necessarily excite our previously anticipated spin-1/2 engineering dimension-1/2 spinor auxiliary multiplet superfield. The analysis of fluctuations yields more evidence that Howeʹs 1997 theorem is specious when applied to Poincaré supergravity or 11D supergravity/M-theory. We end by commenting upon recent advances in this area.