WEI-SHU HOUModak T.2021-07-282021-07-2820212177323https://www.scopus.com/inward/record.uri?eid=2-s2.0-85100457828&doi=10.1142%2fS0217732321300068&partnerID=40&md5=aeef6df16966f12f266859d93e9c96f9https://scholars.lib.ntu.edu.tw/handle/123456789/574918The h(125) boson, discovered only in 2012, is lower than the top quark in mass, hence t → ch search commenced immediately thereafter, with current limits at the per mille level and improving. As the t → ch rate vanishes with the h-H mixing angle cos γ → 0, we briefly review the collider probes of the top changing tcH/tcA coupling ρtc of the exotic CP-even/odd Higgs bosons H/A. Together with an extra top conserving ttH/ttA coupling ρtt, one has an enhanced cbH+ coupling alongside the familiar tbH+ coupling, where H+ is the charged Higgs boson. The main processes we advocate are cg → tH/A → ttc¯, ttt¯ (same-sign top and triple-top), and cg → bH+ → btb¯. We also discuss some related processes such as cg → thh, tZH that depend on cos γ being nonzero, comment briefly on gg → H/A → tt¯,tc¯ resonant production and touch upon the ρtu coupling. ? 2021 World Scientific Publishing Company.review10.1142/S02177323213000682-s2.0-85100457828