Forward photon measurements in ALICE as a probe for low-x gluons

Understand

The low-x gluon density in the proton and, in particular, in nuclei is only very poorly constrained, while a better understanding of the low-x structure is crucial for measurements at the LHC and also for the planning of experiments at future hadron colliders.

• In addition, deviations from linear QCD evolution are expected to appear at low x, potentially leading to gluon saturation and a universal state of hadronic matter, the color-glass condensate.
• However, these effects have not been unambiguously proven to date.
• Fortunately, data from the LHC can be used directly to provide better constraints of the parton distribution functions (PDFs).