Studying the Triple Higgs Self-Coupling Via e+e- --> b bar b HH, t bar t HH at Future Linear e+e- Colliders

We study the triple Higgs self-coupling at future $e^{+}{e}^{-}$ colliders energies, with the reactions $e^{+}{e}^{-}\to b\bar{b}HH$ and $e^{+}e^{-}\to t \bar t HH$\mathrm{.}Weevaluatethetotalcrosssectionof$b\bar bHH$,$t\bar tHH$ and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. The sensitivity of the triple Higgs coupling is considered in the Higgs mass range 110-190 $GeV$, for the energy which is expected to be available at a possible Next Linear $e^{+}{e}^{-}$ Collider with a center-of-mass energy $800,1000,1500$ $GeV$ and luminosity 1000 $f{b}^{-1}$.