Recent progress on Higgs physics at a $γγ$ collider
We review some recent developments in Higgs physics at a $γγ$ collider. We begin with single Higgs boson production in $γγ$ collisions proceeding via the hadronic content of the photon. For SM Higgs masses of current theoretical interest, the resolved photon contributions are non-negligible in precision cross section measurements. We found that production of the heavier Higgs bosons, $H^0$ and $A^0$, of the MSSM can probe regions of the SUSY parameter space that will complement other measurements. We showed that associated $t H^\pm$ production in $γγ$ collisions can be used to make an accurate determination of $\tanβ$ for low and high $\tanβ$ by precision measurements of the $γγ\to H^\pm t +X $ cross section. We then reviewed recent progress on Higgs physics in direct photon processes in which the Higgs bosons are produced via virtual loops. Precision measurements of the magnitude and phase of the $Hγγ$ coupling at a photon collider can be used to determine Higgs parameters related to physics beyond the SM.