# How to take Pz in quasiPDF to infinity to get Light-cone PDF

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• QuantumJames
QuantumJames
When I calculate light-cone PDF by taking pz in quasiPDF to infinity before one-loop integration, I will encounter all the integrations vanish. Such as this integral below:

https://imgur.com/8DbDzsV

This is from one of one-loop quasiPDF diagram, the sail diagram.

The definition is above, W_z is the Wilson line (gauge link) along z direction, and one of the one-loop Feynman diagram is followed:

How can I take pz to infinity before loop integration? Even though I have done the Fourier transform first before taking the limit, there would still be the same problem

https://imgur.com/fZMbh4b

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