News from Extended Scalar Sectors

Abstract

In this proceeding contribution, I give a short overview on selected topics regarding extended scalar sector phenomenology. After a short overview on extended scalar sectors with light scalars at Higgs factories, I concentrate on the Inert Doublet model and recent studies exploring its discovery potential at lepton colliders.

Figures (13)

• Figure 1: Leading-order production cross sections for $e^+\,e^-\,\rightarrow\,Z\,h$(blue) and $e^+\,e^-\,\rightarrow\,h\,\nu_\ell\,\bar{\nu}_\ell$(red) production at an $e^+\,e^-$ collider with a com energy of 250 $$ GeV using Madgraph5 for an SM-like scalar $h$. The contribution of $Z\,h$ to $\nu_\ell\,\bar{\nu}_\ell\,h$ using a factorized approach for the Z decay is also displayed (green). Taken from Robens:2024wbw.
• Figure 2: Taken from Altmann:2025feg for $b\bar{b}$ final states, for various initial state polarization combinations at various integrated luminosities as well as a combination at $2\,{\rm ab}^{-1}$. Results are given for production times decay, normalized to the SM production cross section at that mass.
• Figure 3: Taken from Altmann:2025feg for $\tau^+\,\tau^-$ final states, for an ILC at 250 $$ GeV and an integrated luminosity of $2\,{\rm ab}^{-1}$. Result are shown for various final states and selection criteria for the di-tau decay products. See Altmann:2025feg for details.
• Figure 4: Taken from Altmann:2025feg for $\tau^+\,\tau^-$ final states, viability of different models.
• Figure 5: Taken from Altmann:2025feg for several final states, reach of several searches using a variety of decay modes, center-of-mass energies, and detector simulation approaches. Shown are also the experimental bounds achieved by the LEP collaborations OPAL:2002ifxALEPH:2006tnd.