Heavy charged Higgs boson production at next generation $e^\pm��$ colliders

We assess the potential of future electron-positron linear colliders operating in the $e^\pm��$ mode in detecting charged Higgs bosons with mass around and larger than the top quark mass, using Compton back-scattered photons from laser light. We compare the pair production mode, $e^-��\to e^- H^+H^-$, to a variety of channels involving only one charged Higgs scalar in the final state, such as the tree-level processes $e^-��\to ��_e H^- ��^0 $ ($��^0=h^0,H^0$ and $A^0$) and $e^-��\to ��_e f\bar f H^-$ ($f=b,��$ and $��_��$) as well as the loop-induced channel $e^-��\to ��_e H^-$. We show that, when the charged Higgs boson mass is smaller than or comparable to half the collider energy, $\sqrt s_{ee}\gsim 2M_{H^\pm}$, single production cross sections are of the same size as the pair production rate, whereas, for charged Higgs boson masses larger than $\sqrt s_{ee}/2$, all processes are heavily suppressed. In general, production cross sections of charged Higgs bosons via $e^\pm��$ scatterings are smaller than those induced at an $e^+e^-$ collider and the latter represents a better option to produce and analyse such particles.
18 pages, latex, 9 figures