Study of the top quark production in complementary phase space regions and impact on PDFs in CMS

The first measurement of the top quark pair production cross section ($\sigma_{\rm{t}\bar{\rm{t}}}$) in proton-proton collisions at $\sqrt{s} = 5.02$ TeV is reviewed. The data have been collected by the CMS experiment at the LHC and analyzed considering events with at least one charged lepton. The extraction of $\sigma_{\rm{t}\bar{\rm{t}}}$ can be used to constrain the gluon distribution function (PDF) at large longitudinal parton momentum fraction and to establish experimentally the relation between the top-quark mass as implemented in Monte-Carlo generators and the Lagrangian mass parameter. The impact of the measurement on the determination of the gluon PDF is illustrated through a quantum chromodynamic analysis at next-to-next-to-leading order and the result is furthermore put in context with other top quark measurements in different phase space regions. The measurement has paved the way for the first observation of top quark production in nuclear collisions and the subsequent study of modifications induced on the bound gluon PDF.