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Title: Reconciling large- and small-scale structure in Twin Higgs models

Here, we study possible extensions of the Twin Higgs model that solve the Hierarchy problem and simultaneously address problems of the large- and small-scale structures of the Universe. Besides naturally providing dark matter (DM) candidates as the lightest charged twin fermions, the twin sector contains a light photon and neutrinos, which can modify structure formation relative to the prediction from the ΛCDM paradigm. We focus on two viable scenarios. First, we study a Fraternal Twin Higgs model in which the spin-3/2 baryon $$\hat{Ω}$$~($$\hat{b}$$$\hat{b}$$$\hat{b}$$) and the lepton twin tau $$\hat{τ}$$ contribute to the dominant and subcomponent dark matter densities. A non-decoupled scattering between the twin tau and twin neutrino arising from a gauged twin lepton number symmetry provides a drag force that damps the density inhomogeneity of a dark matter subcomponent. Next, we consider the possibility of introducing a twin hydrogen atom $$\hat{H}$$ as the dominant DM component. After recombination, a small fraction of the twin protons and leptons remains ionized during structure formation, and their scattering to twin neutrinos through a gauged U(1) B-L force provides the mechanism that damps the density inhomogeneity. Both scenarios realize the Partially Acoustic dark matter (PAcDM) scenario and explain the σ 8 discrepancy between the CMB and weak lensing results. Moreover, the self-scattering neutrino behaves as a dark fluid that enhances the size of the Hubble rate H 0 to accommodate the local measurement result while satisfying the CMB constraint. For the small-scale structure, the scattering of $$\hat{Ω}$$ ’s and $$\hat{H}$$’s through the twin photon exchange generates a self-interacting dark matter (SIDM) model that solves the mass deficit problem from dwarf galaxy to galaxy cluster scales. Furthermore, when varying general choices of the twin photon coupling, bounds from the dwarf galaxy and the cluster merger observations can set an upper limit on the twin electric coupling.
 [1] ;  [2]
  1. Univ. of California, Davis, CA (United States). Dept. of Physics
  2. Univ. of Maryland, College Park, MD (United States). Maryland Center for Fundamental Physics, Dept. of Physics
Publication Date:
Grant/Contract Number:
FG02-91ER40674; PHY-1315155; PHY-1066293
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2017; Journal Issue: 9; Journal ID: ISSN 1029-8479
Springer Berlin
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE; National Science Foundation (NSF)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; Cosmology of Theories beyond the SM; Beyond Standard Model
OSTI Identifier: