Polarization of Instantons and Gravity
  Gravity can arise in a conventional non-Abelian gauge theory in which a specific phenomenon takes place. Suppose there is a condensation of polarized instantons and antiinstantons in the vacuum state. Then the excitations of the gauge field in the classical approximation are described through the variables of Riemann geometry satisfying the Einstein equations of general relativity. There are no dimensional coupling constants in the theory. 
M.Yu.Kuchiev (School of Physics, University of New South Wales. On   leave from A.F.Ioffe Physical-Technical Institute)