Turn up the volume: Listening to phase transitions in hot dark sectors

Abstract

Stochastic gravitational wave (GW) backgrounds from first-order phase transitions are an exciting target for future GW observatories and may enable us to study dark sectors with very weak couplings to the Standard Model. In this work we show that such signals may be significantly enhanced for hot dark sectors with a temperature larger than the one of the SM thermal bath. The need to transfer the entropy from the dark sector to the SM after the phase transition can however lead to a substantial dilution of the GW signal. We study this dilution in detail, including the effect of number-changing processes in the dark sector (so-called cannibalism), and show that in large regions of parameter space a net enhancement remains. We apply our findings to a specific example of a dark sector containing a dark Higgs boson and a dark photon and find excellent detection prospects for LISA and the Einstein telescope.

Glueballs in a Thermal Squeezeout Model

“…iments [97,98,127], as well as modifying the spectrum of gravitational waves from other sources [128][129][130][131][132][133].…”

Gravitational wave signatures of a chiral fermion dark matter model

“…In this case, the dark sector could be accessible through gravitational wave signatures. GW signals arising from dark sector phase transition with gauge symmetry assumed to be U(1) [58][59][60][61][62][63][64][65][66][67][68][69], SU(2) [70][71][72][73], and SU(3) [74,75] have been examined and model agnostic analyses were carried out in refs. [76,77].…”

Upper bound on thermal gravitational wave backgrounds from hidden sectors

“…To satisfy observational constraints e.g. from big bang nucleosynthesis, thermalized hidden sectors are generically expected to be colder than the SM plasma[48,49], but it has been argued that larger temperatures can be viable in certain cases[50,51].…”