Higgs Pair-Production in the Standard Model at Next Generation Linear $e^{+}{e}^{-}$ Colliders

We study the Higgs pair-production in the Standard Model of the strong and electroweak interactions at future $e^{+}{e}^{-}$ collider energies, with the reaction $e^{+}{e}^{-}\to t\bar{t}HH$. We evaluated the total cross section of $t\bar{t}HH$ and calculate the number total of events considering the complete set of Feynman diagrams at tree-level. The numerical computation is done for the energy which is expected to be available at a possible Next Linear $e^{+}{e}^{-}$ Collider: with center-of-mass energy $800,1600$ $GeV$ and luminosity 1000 $f{b}^{-1}$.