Mirror twin Higgs cosmology: constraints and a possible resolution to the H0 and S8 tensions

Abstract

The mirror twin Higgs model (MTH) is a solution to the Higgs hierarchy problem that provides well-predicted cosmological signatures with only three extra parameters: the temperature of the twin sector, the abundance of twin baryons, and the vacuum expectation value (VEV) of twin electroweak symmetry breaking. These parameters specify the behavior of twin radiation and the acoustic oscillations of twin baryons, which lead to testable effects on the cosmic microwave background (CMB) and large-scale structure (LSS). While collider searches can only probe the twin VEV, through a fit to cosmological data we show that the existing CMB (Planck18 TTTEEE+lowE+lowT+lensing) and LSS (KV450) data already provide useful constraints on the remaining MTH parameters. Additionally, we show that the presence of twin radiation in this model can raise the Hubble constant H0 while the scattering twin baryons can reduce the matter fluctuations S8, which helps to relax the observed H0 and S8 tensions simultaneously. This scenario is different from the typical ΛCDM + ∆Neff model, in which extra radiation helps with the Hubble tension but worsens the S8 tension. For instance, when including the SH0ES and 2013 Planck SZ data in the fit, we find that a universe with ≳ 20% of the dark matter comprised of twin baryons is preferred over ΛCDM by ∼ 4σ. If the twin sector is indeed responsible for resolving the H0 and S8 tensions, future measurements from the Euclid satellite and CMB Stage 4 experiment will further measure the twin parameters to O(1 − 10%)-level precision. Our study demonstrates how models with hidden naturalness can potentially be probed using precision cosmological data.

Simulating Atomic Dark Matter in Milky Way Analogs

“…This Letter focuses specifically on the Milky Way-like halo m12i, which has a total CDM mass of ∼10 12 M e , a stellar disk of mass 7.4 × 10 10 M e , and a quiet merger history below z < 1 for CDM (Hopkins et al 2018b). The initial transfer functions for the baryons, CDM, and ADM particles are calculated using a modified version of CLASS (Blas et al 2011;Bansal et al 2022aBansal et al , 2022b. MUSIC (Hahn & Abel 2011) is then used to generate initial conditions at z ∼ 100 for the requisite mixture of baryons, CDM, and ADM.…”

“…On cosmic scales, ADM manifests through dark acoustic oscillations and contributions to ΔN eff (Cyr-Racine et al 2014;Gurian et al 2022a). Current cosmological constraints allow for ADM to comprise  10% ( )  of the DM for a wide range of parameters (Bansal et al 2022a(Bansal et al , 2022b. On much smaller scales, the signatures of an ADM subcomponent can potentially be spectacular.…”

The Possibility of Mirror Planet as Planet Nine in the Solar System

“…In addition, mirror particles have a strong interaction within the mirror world, which leads to the mirror-particle-abundant phenomenon as a kind of self-interacting dark matter [14]. Celestial bodies in the normal world, such as halos, stars and planets, are also possible in the mirror world [14,20,24,30].…”

Stepped partially acoustic dark matter: likelihood analysis and cosmological tensions

“…Proposals to solve the S 8 tension include, for example, refs. [58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73]. Unfortunately, many of the most promising proposals to address the H 0 tension lead to an increase in S 8 , making the latter tension more significant.…”