Observability of Charged Higgs through Triple or Double Higgs Production in a General Two Higgs Doublet Model at an e+e- Linear Collider

In this paper the triple Higgs production in a general two Higgs doublet model (2HDM) is studied. The production process is e+e- -> H+H-H0 followed by the charged Higgs decay to a pair of tau nu and the neutral Higgs decay to bb. The alternative process H+W-H0 is also included as a source of charged Higgs signal in the analysis. The focus is on a future e+e- linear collider operating at sqrt(s) = 1.5 TeV. The final state under consideration (tau tau bb ETmiss) is suitable for electroweak background rejection using the b-tagging tools. It is shown that although the signal cross section is small, with a reasonable background suppression, high signal significance values are achievable at an integrated luminosity 500 fb-1 depending on the charged Higgs mass, tanbeta and the CP-odd neutral Higgs mass. Finally results are quoted in terms of the signal significance for charged Higgs in the mass range 170 < mH+ < 400 GeV.