A Guide to Light-Cone PDFs from Lattice QCD: An Overview of Approaches, Techniques, and Results

Figure 40

Flowchart of different methods of accessing partonic distributions considered in this review. Four main stages of every calculation are presented in blue boxes, connected with red/green boxes representing the theoretical and lattice challenges that need to be overcome to go to the next stage. Solid arrows indicate that given types of challenges emerge as a general rule, while dashed arrows signify that a given type of challenge does not have to appear for every method. The red text corresponds to different approaches and their current status. The symbol in parentheses indicates the hadron to which a given type of distribution pertains ( is nucleon and is pion (also other mesons in certain cases)). The considered distributions are PDFs/DAs/GPDs/TMDs, in general for quarks (with an explicit counterexample of gluonic PDFs indicated with parentheses at the end ()). The approach is indicated with small letters before the distribution name: q is quasidistributions, p is pseudodistributions, ht is hadronic tensor, ope is OPE without OPE, ahq is auxiliary heavy quark, alq is auxiliary light quark, and lcs is good lattice cross-sections. Example: qPDFs: quark PDFs of the nucleon accessed with the quasidistribution method.