Off-Shell Photon Light-Cone Transverse Wavefunction atLeading Twist

Abstract

The explicit expression of the transverse photon wavefunctionϕγ⊥(u,P2) at the leading twist with theon-shell and the off-shell momenta are calculated in theeffective low-energy theory derived from the instanton vacuum ofQCD, where both the space-like region as well as the time-like one ofthe momenta for the virtual photons are investigated. Inaddition, the problem about the consistency between the twodifferent definitions of the transverse photon wavefunction withchiral-odd Dirac structure, σμν, has beenconsidered, and proven to be true at the leading order by means ofthe sum rule method. A brief discussion of the dependence of thetransverse light-cone photon wavefunction ϕγ⊥(u,P2)and its coupling, Fγ⊥(u,P2) to the correspondingquark–antiquark current with respect to P2, and that about theend-point behaviour of the transverse photon wavefunction is given.