Broader validity of collinear factorization

Establish whether collinear factorization applies beyond the processes for which it has been rigorously proven, thereby determining the scope of its use in hadronic cross-section calculations.

Background

The paper explains that hadronic cross sections are conventionally decomposed into universal long-distance factors, namely parton distribution functions and fragmentation functions, and perturbatively calculable partonic cross sections. Although collinear factorization has been proven only for certain classes of processes, its broader applicability underlies the theoretical treatment of simultaneous W-boson and charmed-hadron production analyzed in the paper. The authors identify this broader validity as a conjectural issue supported empirically by agreement with data across many processes.