First measurement of the top quark pair production cross section in proton-proton collisions at √s = 13.6 TeV

The first measurement of the top quark pair (tt¯) production cross section in proton-proton collisions at s = 13.6 TeV is presented. Data recorded with the CMS detector at the CERN LHC in Summer 2022, corresponding to an integrated luminosity of 1.21 fb ⁻¹, are analyzed. Events are selected with one or two charged leptons (electrons or muons) and additional jets. A maximum likelihood fit is performed in event categories defined by the number and flavors of the leptons, the number of jets, and the number of jets identified as originating from b quarks. An inclusive tt¯ production cross section of 881 ± 23 (stat + syst) ± 20 (lumi) pb is measured, in agreement with the standard model prediction of 924 ₋₄₀ ⁺³² pb.