A search is presented for new Higgs bosons in proton-proton (pp) collision events in which a same-sign top quark
pair is produced in association with a jet, via the pp → tH∕A → ttc and pp → tH∕A → ttu processes. Here, H and
A represent the extra scalar and pseudoscalar boson, respectively, of the second Higgs doublet in the generalized
two-Higgs-doublet model (g2HDM). The search is based on pp collision data collected at a center-of-mass energy
of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb−1. Final states
with a same-sign lepton pair in association with jets and missing transverse momentum are considered. New
Higgs bosons in the 200–1000 GeV mass range and new Yukawa couplings between 0.1 and 1.0 are targeted
in the search, for scenarios in which either H or A appear alone, or in which they coexist and interfere. No
significant excess above the standard model prediction is observed. Exclusion limits are derived in the context of
the g2HDM.