The impact of intrinsic charm on the parton distribution functions
  In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function $F_2^c$. Since IC distribution is dominant at large Bjorken variable $x$, normally, it is expected that it can be explored only at large $x$. But, by studying the correlation of the charm density in the proton with $F_2^c$, we are going to show that the IC component can also be effective at low $x$. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC $F_2^c$ data that are recognized as clear evidence for existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower $x$ values, i.e. $x< $0.05, but these analyses can give us new information about the impact of EMC data and IC contribution on the behaviour of PDFs. 
Alireza Aleedaneshvar, Muhammad Goharipour, Saeedeh Rostami
hep-ph