Interplay between new physics in one-loop Higgs couplings and the top-quark Yukawa coupling

Understand

After the discovery of a 126 GeV state at the LHC it is imperative to establish whether this particle really is the Higgs boson of the standard model.

• The early measurements have not yet pinpointed any of the Higgs couplings to fermions, the Yukawa couplings of the standard model.
• In this paper we study the values of the top-quark-Higgs coupling, $g_{ht\bar{t}}$, that are still allowed by the one-loop couplings of the Higgs to two gluons or two photons.
• We first assume that both the gluon fusion production of the Higgs and its decay into two photons proceed through loops with standard model particles only, albeit with an arbitrary top-Higgs coupling.