On the top-antitop invariant mass spectrum at the LHC from a Higgs boson signal perspective

Abstract

We investigate the effect of one-loop corrections of ${\cal O}(α_S^2α_W)$ on the $t\bar t$ invariant mass spectrum at the Large Hadron Collider (LHC) in presence of both resonant and non-resonant Higgs boson effects. We show that corrections of ${\cal O}(α_S^2α_W)$ involving a non-resonant Higgs boson are comparable to or even larger than those involving interference with the s-channel resonant Higgs boson amplitude and that both of these are subleading with respect to all other (non-Higgs) diagrams through that order. We also compute the contribution through ${\cal O}(α_S^2α_W^2)$ of resonant Higgs boson production (i.e. Higgs production via $gg$ fusion) as well as the pure QCD ones of ${\cal O}(α_S^3)$. Altogether, we show that the well known peak-dip structure of the $M_{t\bar t}$ spectrum emerging from interference effects between the $t,u$-channel $gg$-induced Leading Order (LO) QCD diagrams and the one due to a Higgs boson in s-channel via $gg$-fusion is drastically swamped by the remainder of the terms of ${\cal O}(α_S^2α_W)$ discussed above.