A Weak Gravity Conjecture for Scalar Field Theories
  We show that the recently proposed weak gravity conjecture\cite{AMNV0601} can be extended to a class of scalar field theories. Taking gravity into account, we find an upper bound on the gravity interaction strength, expressed in terms of scalar coupling parameters. This conjecture is supported by some two-dimensional models and noncommutative field theories. 
Miao Li, Wei Song, Yushu Song and Tower Wang