The triple Higgs boson self-coupling at future linear e+e- colliders energies:: ILC and CLIC

We analyzed the triple Higgs boson self-coupling at future e(+)e(-) colliders energies, with the reactions e(+)e(-) -> b (b) over bar HH, t (t) over bar HH. We evaluate the total cross-sections for both b (b) over bar HH and t (t) over bar HH, and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. We vary the triple coupling K lambda H-3 within the range K = -1 and +2. The numerical computation is done for the energies expected to be available at a possible Future Linear e(+)e(-) Collider with a center-of-mass energy 800, 1000, 1500GeV and a luminosity 1000fb(-1). Our analysis is also extended to a center-of-mass energy 3 TeV and luminosities of 1000 and 5000 fb(-1). We found that for the process e(+)e(-) -> b (b) over bar HH, the complete calculation differs only by 3% from the approximate calculation e(+)e(-) -> ZHH(Z -> b (b) over bar), while for the process e(+)e(-) -> t (t) over bar HH, the expected number of events, considering the decay products of both t and H, is not enough to obtain an accurate determination of the triple Higgs boson*self-coupling.