The observation of $t\bar th(125)$ production at the Large Hadron Collider (LHC) is the first direct measurement of the top Yukawa coupling. It opens the window on an extra top Yukawa coupling, $\rho_{ tt}$, from a second Higgs doublet, without a $Z_2$ symmetry to forbid flavor changing neutral Higgs couplings. We show that $t\bar th$ and Higgs property measurements at the High Luminosity LHC can constrain the ${ \rm Re}\,\rho_{ tt}$--${ \rm Im}\,\rho_{ tt}$ parameter space that could drive electroweak baryogenesis, but the $\Gamma_h$ width measurement must be considerably improved beyond current projections.
Categories: hep-ph hep-ex