A twist-4 effect in the parton evolution processes

Recently, a research group reported that they can fit the F₂ data well by using the Altarelli-Parisi evolution equation with a valence-like initial gluon distribution, which means that we need not consider the high twist effects in the proton. In this letter, we point out that their initial gluon distribution is unreasonable for the proton structure function. With the reasonable initial distributions, we find that the high twist corrections to the Altarelli-Parisi evolution equation is necessary.