Filtered asymmetric dark matter during the Peccei-Quinn phase transition

Abstract

In this paper, we propose a bubble filtering-out mechanism for an asymmetric dark matter scenario during the Peccei-Quinn (PQ) phase transition. Based on a QCD axion model, extended by extra chiral neutrinos, we show that the PQ phase transition can be first order in the parameter space of the model and regarding the PQ symmetry breaking scale, the mechanism can generate PeV-scale heavy neutrinos as a dark matter candidate. Considering a CP-violating source, during the phase transition, discriminating between the neutrino and antineutrino number density, we find the observed dark matter relic abundance, such that the setup can be applied to the first order phase transition with different strengths. We then calculate effective couplings of the QCD axion addressing the strong CP problem within the model. We also study the energy density spectrum of gravitational waves generated from the first order phase transition and show that the signals can be detected by future ground-based detectors such as Einstein Telescope. In particular, for a visible heavy axion case of the model, it is shown that gravitational waves can be probed by DECIGO and BBO interferometers. Furthermore, we discuss the dark matter-standard model neutrino annihilation process as a source for the creation of PeV-scale neutrinos.

Electroweak bubble wall expansion: gravitational waves and baryogenesis in Standard Model-like thermal plasma

“…Furthermore in this model the cutoff scales Λ and Λ CP are the only parameters that have to be fixed and they are disentangled with respect to the bubble wall properties and the BAU, respectively. 4 The outcome of the computation of the bubble wall shape and speed is displayed in figure 11 which shows different cross sectional views of the velocity, thickness and amplitude as well as their dependence on Λ. The main qualitative results found for the scalar singlet JHEP02(2022)017 The cutoff Λ in the SMEFT completely determines the character of the FOPT with smaller values of Λ giving the strongest possible transitions.…”

“…Reminding ourselves that the velocity is determined by finding the roots of the moments introduced in eqs. (4.16), (4.17) and that M 1 mostly fixes v w as can be appreciated in figure (4), it is natural to ask what is the relation between M 1 and the approximation in eq. 8.…”

“…Cosmological first order phase transitions (FOPT) could be a vital ingredient in understanding the mechanism of dark matter production [1][2][3][4], account for the baryon asymmetry JHEP02(2022)017 of the universe [5][6][7][8] and be related to the origin of neutrino masses [9]. Additionally they could lead to an observable stochastic gravity wave (GW) background [10].…”

“…where the sum is over all particles that become massive and g i the number of degrees of freedom. From these equations one obtains v = 30 i π 2 g i T 4 .…”

Supercool composite Dark Matter beyond 100 TeV

“…19 Other ways to evade this bound are, for example, DM dilution after a matter era [128,[223][224][225][226][227][228][229][230][231][232][233], or having a dark sector being much cooler than SM [234,235], DM becoming heavy only after freezing-out [236], DM annihilating with one spectator field [237,238] or with many of them [239], DM forming an extended object which undergoes a second annihilation stage [240][241][242]. Mechanisms involving phase transitions include the possibility of a short inflationary stage associated with perturbative DM mass generation [147], DM filtered [243][244][245] or squeezed-out [246][247][248] by non-relativistic bubble wall motion, DM produced by elastic bubble-bubble collisions [249] or perturbative plasma interactions with relativistic walls [250]. (In contrast with these last possibilities, the mechanism which we studied in [45] and which we review in the present work, relies on a strongly interacting theory, with relativistic bubble walls, which come from effective potentials which result in inelastic bubble wall collisions.…”