Pseudo and quasi gluon PDF in the BFKL approximation

Abstract

I study the behavior of the gauge-invariant gluon bi-local operator with space-like separation at large longitudinal distances. Performing the Fourier transform, I also calculate the behavior of the pseudo and quasi gluon PDF at low Bjorken $x$ and compare it with the leading and next-to-leading twist approximation. I show that the pseudo-PDF and quasi-PDF are very different in this regime and that the higher twist corrections of the quasi-PDF come in not as inverse powers of $P$ but as inverse powers of $x_B P$.