On relation between Parton Branching Approach and CCFM evolution

Physical review / D D 101(3), 034022 (2020). doi:10.1103/PhysRevD.101.034022
We consider the associated production of electroweak gauge bosons and charm or beauty quark jets at the LHC using the kT-factorization framework. We apply the transverse momentum dependent (TMD) parton distributions in a proton obtained from the parton branching (PB) method as well as from the Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation. For the PB approach, our prescription merges the standard leading order O(ααs) kT-factorization calculations with several tree-level next-to-leading order O(ααs2) off-shell production amplitudes. For the CCFM scenario, our consideration is based on the O(ααs2) off-shell gluon-gluon fusion subprocess g*g*→Z/W+QQ¯ and some O(ααs2) subprocesses involving quark interactions, taken into account in conventional (collinear) QCD factorization. We find that the W+c and Z+b cross sections, calculated within the PB and CCFM-based schemes with the proper choice of leading and next-to-leading subprocesses, are in good agreement with each other, thus establishing a correspondence between these two scenarios. A comparison with the latest LHC experimental data is given and the necessity for the proper off-shell treatment of the production amplitudes in determination of the parameters of the TMD parton density is demonstrated.
Published by Inst.302363, Melville, NY