Probing Charged Scalars at Photon Colliders: One-Loop Effects in the Inert Doublet Model

We present a comprehensive full one-loop analysis of charged scalar pair production in photon–photon collisions, (\gamma\gamma \to H^{\pm}H^{\mp}), within the framework of the Inert Doublet Model (IDM). This process constitutes one of the most promising channels to directly probe the extended scalar sector predicted by the IDM at future high-energy photon colliders. Owing to the clean environment of photon-induced processes, this reaction offers a sensitive enviroment for investigating the properties of inert charged scalars and their interactions.

The calculation includes the complete set of electroweak virtual corrections together with the contributions from real photon emission required to ensure the cancellation of infrared singularities. The numerical analysis is performed consistently under current theoretical and experimental constraints, including perturbative unitarity, vacuum stability, electroweak precision observables, collider limits, and dark matter constraints. Several representative benchmark scenarios are considered in order to explore different regions of the IDM parameter space.

Our results show that radiative corrections play a crucial role and can significantly modify the tree-level predictions. In particular, the magnitude of the corrections is strongly correlated with the charged scalar mass and the trilinear scalar coupling. Depending on the center-of-mass energy and the chosen benchmark scenario, the corrections vary from moderate negative contributions to sizable positive enhancements, reaching values of approximately 60% at high energies and near specific threshold regions.

These findings demonstrate that higher-order effects are indispensable for precise theoretical predictions and for the reliable interpretation of future collider measurements. The process (\gamma\gamma \to H^{\pm}H^{\mp}) therefore emerges as a powerful probe of the IDM and of extended scalar sectors beyond the Standard Model.