First measurement of the differential cross section for ttbar production in the dilepton final state at sqrts = 13 TeV

Normalized differential top quark pair ($\mathrm{t \bar t}$) production cross sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV at the CERN LHC. The data were recorded in 2015 with the CMS detector and correspond to an integrated luminosity of 42 $\mathrm{pb^{-1}}$. The measurements are performed in the dilepton decay channels ($\mathrm{e^+e^-}$, $\mu^+\mu^-$, and $\mu^{\pm} \mathrm{e^{\mp}}$). The $\mathrm{t \bar t}$ production cross section is measured as a function of kinematic properties of the top quarks and the $\mathrm{t \bar t}$ system, as well as of the jet multiplicity in the event. Several predictions from perturbative QCD calculations are confronted with the data and are found to describe them well within large statistical uncertainties.