Bounding the top Yukawa coupling with Higgs-associated single-top production

After the discovery of the 125 GeV scalar boson with gauge properties similar to the Standard Model (SM) Higgs, the search for beyond the SM interactions will focus on studying the discovered particles’ coupling properties more precisely and shedding light on the relation of fermion masses with the electroweak vacuum. The large mass of the top quark and the SM-predicted order one top Yukawa coupling is a natural candidate for beyond the SM physics, though experimentally challenging to constrain. In this paper, we argue that investigating angular correlations in pp→tHj production provides an excellent handle to constrain the top Yukawa coupling yt via direct measurements, even when we focus on rare exclusive final states. We perform a hadron-level analysis and show that we may expect to constrain yt≳0.5ySMt at 95%–99% confidence level at the high luminosity LHC using semileptonic top decays and H→γγ alone, by employing a two-channel measurement approach