Testing electroweak scale seesaw models at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mi>γ</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi></mml:math> colliders
Arindam Das, Sanjoy Mandal, Sujay Shil
Abstract
We investigate the possibilities of probing the electroweak scale seesaw scenarios such as type-I, type-II, and type-III seesaw at ${e}^{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{\gamma}$ colliders. For the case of type-I seesaw, the heavy neutrinos can be produced at ${e}^{\ensuremath{-}}\ensuremath{\gamma}$ colliders in association with a $W$ boson. We study a variety of final states in this case, including single and multilepton modes in association with jets to estimate bounds on the light-heavy neutrino mixing angle. In case of type-II seesaw, doubly charged multiplets of the $\mathrm{SU}(2{)}_{L}$ triplet scalar can be produced in pair at $\ensuremath{\gamma}\ensuremath{\gamma}$ collider. We study the multileptonic decay modes coming from this pair production of doubly charged Higgs and show how one can probe neutrino mass hierarchy. We also study same-sign $W$ boson production from the doubly charged Higgs to study multilepton modes in association with missing energy. From the type-III seesaw, we study same-sign $\mathrm{dilepton}+\text{jets}$ and $\mathrm{trilepton}+\text{jets}$ modes at ${e}^{\ensuremath{-}}\ensuremath{\gamma}$ collider which are coming from the neutral and charged component of the triplet fermion in association with a $W$ boson and a $Z$ boson, respectively. Due to the existing limits on the triplet fermions from the LHC we choose heavier mass so that the gauge boson originating from the decay of a neutral multiplet can be sufficiently boosted producing a fat-jet signature in association with same-sign dilepton and trilepton. Finally, we estimate bounds on the light neutrino-heavy triplet fermion mixing angle and compare them with the existing bounds.