Dark matter freeze out during an early cosmological period of QCD confinement

Self Cite

In the framework where the strong coupling is dynamical, the QCD sector may confine at a much higher temperature than it would in the Standard Model, and the temperature-dependent mass of the QCD axion evolves in a non-trivial way. We find that, depending on the evolution of ΛQCD, the axion field may undergo multiple distinct phases of damping and oscillation leading generically to a suppression of its relic abundance. Such a suppression could therefore open up a wide range of parameter space, resurrecting in particular axion dark-matter models with a large Peccei-Quinn scale fa ≫ 1012 GeV, i.e., with a lighter mass than the standard QCD axion.

Section: Jhep12(2021)216mentioning

confidence: 99%

Resurrecting low-mass axion dark matter via a dynamical QCD scale

Heurtier

Huang

Tait

2021

Self Cite

“…Furthermore, the general idea of suppressing direct detection by enhancing the relative annihilation rate at early times has also been studied before, see e.g. [1,8,93].…”

Section: Jhep08(2021)009mentioning

confidence: 99%

Twin Higgs portal dark matter

Curtin

Gryba

2021

Many minimal models of dark matter (DM) or canonical solutions to the hierarchy problem are either excluded or severely constrained by LHC and direct detection null results. In particular, Higgs Portal Dark Matter (HPDM) features a scalar coupling to the Higgs via a quartic interaction, and obtaining the measured relic density via thermal freeze-out gives definite direct detection predictions which are now almost entirely excluded. The Twin Higgs solves the little hierarchy problem without coloured top partners by introducing a twin sector related to the Standard Model (SM) by a discrete symmetry. We generalize HPDM to arbitrary Twin Higgs models and introduce Twin Higgs Portal Dark Matter (THPDM), which features a DM candidate with an SU(4)-invariant quartic coupling to the Twin Higgs scalar sector. Given the size of quadratic corrections to the DM mass, its most motivated scale is near the mass of the radial mode. In that case, DM annihilation proceeds with the full Twin Higgs portal coupling, while direct detection is suppressed by the pNGB nature of the 125 GeV Higgs. For a standard cosmological history, this results in a predicted direct detection signal for THPDM that is orders of magnitude below that of HPDM with very little dependence on the precise details of the twin sector, evading current bounds but predicting possible signals at next generation experiments. In many Twin Higgs models, twin radiation contributions to ∆Neff are suppressed by an asymmetric reheating mechanism. We study this by extending the νMTH and X MTH models to include THPDM and compute the viable parameter space according to the latest CMB bounds. The injected entropy dilutes the DM abundance as well, resulting in additional suppression of direct detection below the neutrino floor.

“…This may be able to reproduce some of the non-standard QCD dynamics discussed in refs. [83][84][85].…”

Section: Qcd Phase Transition and The Qcd Axionmentioning

confidence: 99%

Avoided deconfinement in Randall-Sundrum models

Agrawal

Nee

2021

We study first order phase transitions in Randall-Sundrum models in the early universe dual to confinement in large-N gauge theories. The transition rate to the confined phase is suppressed by a factor exp(−N2), and may not complete for N » 1, instead leading to an eternally inflating phase. To avoid this fate, the resulting constraint on N makes the RS effective field theory only marginally under control. We present a mechanism where the IR brane remains stabilized at very high temperature, so that the theory stays in the confined phase at all times after inflation and reheating. We call this mechanism avoided deconfinement. The mechanism involves adding new scalar fields on the IR brane which provide a stablilizing contribution to the radion potential at finite temperature, in a spirit similar to Weinberg’s symmetry non-restoration mechanism. Avoided deconfinement allows for a viable cosmology for theories with parametrically large N. Early universe cosmological phenomena such as WIMP freeze-out, axion abundance, baryogenesis, phase transitions, and gravitational wave signatures are qualitatively modified.