Test of the triple Higgs boson form factor in $\mu^-\mu^+\to HH$
  We study the sensitivity of the process $\mu^-\mu^+\to HH$ to the $q^2$-dependence of the $HHH$ form factor, which can reflect the Higgs boson structure, especially in the case of compositeness. We compute the Born and 1 loop SM contribution to this process. We then show how the $\mu^-\mu^+\to HH$ polarized and unpolarized cross sections are modified by the presence of various types of anomalous contributions to the $HHH$ form factor, in particular Higgs constituents in the case of compositeness. 
G.J. Gounaris and F.M. Renard
hep-ph