Measurement of the Triple-Differential Cross-Section of Z+Jet Production with the CMS Detector at 13 TeV

For understanding and interpreting particle interactions at hadron colliders, the description of the hadrons’ constituents is essential, since hadrons are not fundamental particles. The constituents of a hadron, the partons, each carry a different momentum fraction of the total hadron. These momentum fractions are described by the so-called parton distribution functions (PDFs). Due to the factorization theorem of Quantum Chromodynamics (QCD), the PDFs are the same for all scattering processes.

Multiple different production channels are expected to improve the precision of the experimentally obtained PDFs, including vector boson production in association with a jet. The presented analysis covers this crucial ingredient in the context of the Z boson production with at least one jet. A triple differential measurement provides an insight into the different contributions from the proton’s constituents to the Z+jet production in different regions of the analyzed phase space.

The triple-differential inclusive cross-section is measured as a function of three different kinematic variables, namely the transverse momentum of the Z boson, the difference in rapidity between the Z boson and the jet, as well as the boost of the center-of-mass system. Those variables allow for a suitable division of the phase space in order to obtain a better sensitivity to the partonic sub-processes and the initial state parton momenta. The presented measurement is expected to contribute to a more precise determination of the PDFs, especially the gluon PDF.