Abstract
Restoration of the electroweak symmetry at temperatures around the Higgs mass is linked to tight phenomenological constraints on many baryogenesis scenarios. A potential remedy can be found in mechanisms of electroweak symmetry non-restoration (SNR), in which symmetry breaking is extended to higher temperatures due to new states with couplings to the Standard Model. Here we show that, in the presence of a second Higgs doublet, SNR can be realized with only a handful of new fermions which can be identified as viable dark matter candidates consistent with all current observational constraints. The competing requirements on this class of models allow for SNR at temperatures up to ∼TeV, and imply the presence of sub-TeV new physics with sizable interactions with the Standard Model. As a result this scenario is highly testable with signals in reach of next-generation collider and dark matter direct detection experiments.
Highlights
Electroweak symmetry non-restoration (SNR) can change the minimal temperature at which sphalerons are active if the scale of electroweak restoration is altered [16, 17]
A potential remedy can be found in mechanisms of electroweak symmetry non-restoration (SNR), in which symmetry breaking is extended to higher temperatures due to new states with couplings to the Standard Model
In the presence of a second Higgs doublet, SNR can be realized with only a handful of new fermions which can be identified as viable dark matter candidates consistent with all current observational constraints
Summary
We shall start by making some comments regarding the need for a second Higgs doublet in scenarios in which SNR is linked to the DM relic density. One of the reasons for this outcome is the p-wave suppression of the annihilation cross-section This can be remedied by adding a pseudo-scalar interaction χiγ5χh2/Λwhich provides an s-wave annihilation channel, permitting the correct χ relic density to be reproduced with higher energy cutoff scales: 6.3 TeV (2.9). The spin-independent DM-nucleon cross-section induced by the scalar interaction (see appendix C) is currently bounded as follows [30] Such a large suppression of Higgs-χ interactions has to be compensated by a large number of new fermions in order to have SNR, see eq (2.4), nχ > Λ/mχ0 300. This number is in turn incompatible with the relic density requirement of eq (2.9) unless Λ 350 GeV. In order to allow for that we will separate the SNR sector from the SM quark sector by introducing the second Higgs doublet, as we will discuss
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