Nuclear effects in parton densities
A precise knowledge of the parton distribution functions (PDFs) is crucial for any study involving at least one proton in the initial state. When protons are replaced by nuclei, the non trivial modifications of the cross-sections can be attributed to changes in the PDFs and/or the fragmentation functions (FFs) due to the medium. These nuclear PDFs (nPDFs) and FFs (nFFs) are relevant for l+A, p+A and A+A collisions, where they can help disentangle cold nuclear matter effects from genuinely new phenomena. Moreover, they can be used to improve the flavour separation of the quarks in e+p and p+p experiments. Despite decades of dedicated studies, a full description of the nPDFs and nFFs is still missing. In this talk I will review the current status of in medium modification of PDFs and FFs and discuss the latest results and possibilities for improvements in future colliders.