We explore the mechanism that can explain the production of lepton asymmetry and two types of sterile neutrino dark matter. The first type involves heavy sterile dark matter produced directly by the decay of Q-balls which are formed by first-order phase transition in the early universe; the second consists of keV sterile neutrino dark matter, produced resonantly with the aid of lepton asymmetry from Q-ball decay. Besides, gravitational waves from cosmic strings generated during the phase transition process could be detected at future interferometers.

China

Jiucheng Ma

Siyu Jiang

Xiu-Fei Li

Impact of Q-balls formed by first-order phase transition on sterile neutrino dark matter

As a new type of dynamical dark matter mechanism, we discuss the stability of the gauged Q-ball dark matter and its production mechanism through a cosmological first-order phase transition. This work delves into the study of gauged Q-ball dark matter generated during the cosmic phase transition. We demonstrate detailed discussions on the stability of gauged Q-balls to rigorously constrain their charge and mass ranges. Additionally, employing analytic approximations and the mapping method, we provide qualitative insights into gauged Q-balls. We establish an upper limit on the gauge coupling constant and give the relic density of stable gauged Q-ball dark matter formed during a first-order phase transition. Furthermore, we discuss potential observational signatures or constraints of gauged Q-ball dark matter, including astronomical observations and gravitational wave signals.

Fa Huang

South Korea

Pyungwon Ko

Gauged Q-ball dark matter through a cosmological first-order phase transition

Motivated by current status of dark matter (DM) search, a new type of DM production mechanism is proposed based on the dynamical process of a strong first-order phase transition in the early Universe, namely, the filtered DM mechanism. We study the hydrodynamic effects on the DM relic density. By detailed calculations, we demonstrate that the hydrodynamic modes with the corresponding hydrodynamic heating effects play essential roles in determining the DM relic density. The corresponding phase transition gravitational wave could help to probe this new mechanism.

Fa Peng Huang

Chong Sheng Li

Hydrodynamic effects on the filtered dark matter produced by a first-order phase transition

The bubble wall velocity is essential for the spectra of phase-transition gravitational waves, electroweak baryogenesis and the dynamical dark matter mechanism. We perform detailed calculations of the bubble wall velocity in the well-motivated inert doublet model using the microphysical approach with some recent new methods.