Speaker
Description
We investigate electroweak scale seesaw scenarios such as type-I, II
and III seesaw in the context of $e^-\gamma$ and $\gamma\gamma$ colliders.
The heavy neutrinos~(triplet fermions) can be produced at $e^-\gamma$ colliders
in association with a W boson. We study LNV final state such as $e^{+} + 4j$
where the associated W boson decay hadronically. We also consider the leptonic
decay of the W boson giving rise to the same sign dilepton signal in association
with jets and missing momentum. Studying these signals and generic backgrounds
we estimate bounds on the light-heavy neutrino mixing angle from the
$e^-\gamma$ collider which can provide stronger limits than the existing ones,
atleast for relatively higher mass of heavy neutrinos. In case of type-II seesaw
singly and doubly charged multiplets of the SU(2)L triplet scalar can be produced
at $e^-\gamma$ and $\gamma\gamma$ colliders respectively. We study the
leptonic decay modes of the charged multiplets which depend on the
corresponding Yukawa coupling with the lepton doublet involving the light neutrino
mass. We find that one can easily distinguish between neutrino mass hierarchy
using these final states.
