Speaker
Description
Besides solving the hierarchy problem by introducing an SM-neutral twin sector (hidden naturalness), Twin Higgs models naturally furnish a WIMP-like dark matter (DM) scenario with an attractive DM candidate ${}-{}$ the lightest twin charged lepton. The twin particle spectrum contains light twin particles, including the twin-photon and neutrinos, that are customarily assumed to be either heavy or altogether absent in order to bypass cosmological constraints on the dark radiation (DR). As we will demonstrate in this talk, however, the existence of light twin particles can in fact resolve various large- and small-scale structure puzzles while still fulfilling current cosmological constraints.
We will discuss an example of a minimal Twin Higgs scenario in the Fraternal Twin Higgs model with the twin tau playing the role of the DM. We take twin-neutrinos to be self-interacting DR coupled through a gauged U$(1)_{B-L}$ symmetry in the twin sector. We find that the twin-tau self-interaction through twin-photon exchange can address anomalies related to halo structures. Further, the twin-tau/twin-neutrino interaction provides a mechanism for damping the large scale structure power spectrum and an explanation for the $\sigma_8$ discrepancy between the CMB and weak lensing measurements.