An index of summability for pairs of Banach spaces
  We introduce the notion of index of summability for pairs of Banach spaces; for Banach spaces E; F, this index plays the role of a kind of measure of how the m-homogeneous polynomials from E to F are far from being absolutely summing. In some cases the optimal index of summability is computed. 
M. Maia, D. Pellegrino, J. Santos
math.FA