Double-logarithmic asymptotics of the electromagnetic form factors of   the electron and quark
  The asymptotic behaviour of the electromagnetic form factors of the electron and quark is obtained in the double-logarithmic approximation for Sudakov kinematics, i.e. for the case that the value of the momentum transfer is much greater than the mass of the particle. 
B. I. Ermolaev and S. I. Troyan