Azimuthal decorrelation between a jet and a Z boson at hadron colliders

Abstract

We revisit the azimuthal decorrelation δϕ between a jet and a Z boson produced at hadron colliders. Employing different recombination schemes for the jets leads to significantly different NLL-resummed predictions for the distribution of this quantity. Specifically when the jets are reconstructed with the E-scheme (i.e., four-momentum addition) in the k_t or anti-k_t clustering algorithms, then the resummation becomes highly non-trivial due to the presence of non-global and/or clustering logarithms. We evaluate these logarithms analytically at two loops and numerically to all orders in the large-N_c limit, and present a full NLL resummation of δϕ. We extend the accuracy of the perturbative expansion of the resummed distribution at fixed order to NNLL accuracy by including $\mathcal{O}$(α_s) NLO corrections obtained with MadGraph5_aMC@NLO. We compare our findings with results of various Monte Carlo event generators and with experimental data from the CMS collaboration.