Charmonia production from b-hadron decays at LHC with $$k_T$$kT-factorization: $$J/\psi $$J/ψ, $$\psi (2S)$$ψ(2S) and $$J/\psi + Z$$J/ψ+Z

Abstract We consider the production of $$J/\psi $$ J/ψ and $$\psi (2S)$$ ψ(2S) mesons originating from the decays of b-flavored hadrons at the LHC using the $$k_T$$ kT -factorization approach. Our analysis covers both inclusive charmonia production and production of $$J/\psi $$ J/ψ mesons in association with Z bosons. We apply the transverse momentum dependent (or unintegrated) gluon density in a proton derived from Catani–Ciafaloni–Fiorani–Marchesini (CCFM) evolution equation and adopt fragmentation functions based on the non-relativistic QCD factorization to describe the inclusive b-hadron decays into the different charmonium states. Our predictions agree well with latest experimental data taken by the CMS, ATLAS and LHCb Collaborations at $$\sqrt{s} = 7$$ s=7 , 8 and 13 TeV. The contributions from double parton scattering to the associated non-prompt $$J/\psi + Z$$ J/ψ+Z production are estimated and found to be small.