Azimuthal correlations in Z+jets events at 13 TeV

The production of $Z$ bosons associated with jets is measured at $\sqrt{s}=13~\mathrm{TeV}$ with data recorded at the LHC corresponding to a luminosity of $36.3~\mathrm{fb}^{-1}$. The multiplicity of jets with $p_\mathrm{T}(Z) > 30~\mathrm{GeV}$ is measured for different regions of the Z transverse momentum, ranging from $p_\mathrm{T}(Z) < 10~\mathrm{GeV}$ to $p_\mathrm{T}(Z) >100~\mathrm{GeV}$. The azimuthal correlation $\Delta \phi$ between the $Z$ boson and the leading jet as well as the correlation $\Delta\phi (j_1, j_2)$ between the two leading jets is measured for different $p_\mathrm{T}(Z)$. The measurements are compared with predictions with up to two additional partons merged at next-to-leading order supplemented with parton shower and hadronization, with predictions at NLO for up to two additional partons based on transverse momentum dependent parton distributions and the corresponding parton showers, and with resummed predictions of Z production at NNLO supplemented with conventional parton shower. Predictions based on matrix element calculations with up to two additional partons at NLO come close to the measurements.